FEB 2 EVENT…. ALL RAIN VA NC but Massive Winter Storm for MIDWEST

Posted by wxrisk | GENERAL | Sunday 30 January 2011 3:16 pm

1400 EST    JAN 30

 For most of the winter the Midwest which has been very cold but it has NOT  seen a lot of significant winter storm activity.  But that is about to change as the models continue to show a massive system coming out of Eastern Texas and tracking up through the heart of the Ohio Valley.

This system has major implications for every body and will be the biggest storm of the winter (so far)  with regard to its impact over the U.S.  Driving the overall pattern and complicating the situation is the the involvement of a massive arctic HIGH  coming out of Western Canada and the intense Low pressure area itself.  The interaction between these two features is going to cause a stunningly strong pressure gradient all over the Midwest  and  this is going to bring about blizzard conditions to some areas.  For the  Northeast US — and especially the big cities   in the  I-95 corridor-  this  system is going to be a rude shock as many   have come  believe    that Major winter storms  are now some  some sort of  US Constitutional right.

Although the precipitation may start as snow and sleet over Philly    NYC and Boston it will change to rain as the system tracks into western Pennsylvania from Ohio and pulls up to warm  air  at  850 mb and  all the way down to the surface.
This first image  is the  500 MB   map ( JET STREAM)   from the 12z GFS   at  36 hours.  I am presenting this image to show why  this is going to be the a Midwest storm and cannot possibly become  Northeast.  As you can see there  is Ridge  over the West coast which is a pretty good position for east coast winter storm lovers.  But the problem it is that these two pieces of energy  in the Jet stream –  called  “SHORT   WAVES” in the weather  biz — are located very far to the west.  One is located over the southwest states and the other dropping out of Western Canada into Montana.  These two features are about ready to phase or merge into one big system which we can see the here ay  60 hrs.  This occurs west of the Mississippi River which is why this is a Midwest winter storm.

This image shows the European model at  500 MB from early this morning valid for 72 hours or Wednesday night.  As you can see it is very similar to the 12z GFS  at  60 hr .  

This is the surface reflection of this monster storm valid Tuesday evening.  The thing to note here it is  the pressure gradient or the Isobars between the the developing and intensifying Low pressure area and a monster arctic High coming out of Montana.

This image represents the upper level features of the same Low….  The top map represents the  850 mb level and the Bottom map  the 700 MB level.  I have superimposed the the 50 low over South Central Illinois see  you can see the how impressive the system has.  Note all the red lines over the Deep South into the Middle Atlantic  region…  Which is indicative of the warm air surging northward  into   TN KY   NC  VA  MF   and WVA .

This image represents the  TOTAL  FORECASTED SNOWFALL for the next    3   days from  the  12z NAM  model.

This Image– the same thing   but  from the 12z  GFS.

As you can see both models show a huge stripe of anywhere from 10 to 20 inches of snow.  In fact some of the actual extrapolated data and bufkit shows Chicago getting  20-25″   of snow and this sort of stunningly huge amount of snow extends into places such as Peoria    Quincy  and Springfield.

 Now for the Middle Atlantic region the temperatures will warm significantly as this Low pressure area moves through the Midwest and then tracks into Ohio and Western Pennsylvania.  We can see the track of the Low in great detail on these two images.  This  next    two images are  valid Wednesday morning   and afternoon.  We can clearly see the model showing a significant dry slot moving into Virginia during the afternoon.


  Temperatures are likely to reach into the 60s  over much of North Carolina and Virginia… BEFORE  the rains    hit.  This strongly implies that the areas from  I-95/ I-85  eastward towards the ocean will have the greatest chance of seeing temperatures reach above 70°.  And if there  is any sunshine at all over Eastern Virginia and Eastern North Carolina temperatures can reach into the middle 70s!

Behind this system the pattern will continue to favor in Midwest.  There is   No hint  of the   pattern  shifting back to the  East coast winter pattern we have seen for the last eight weeks. 

 There is another system coming out of the Gulf of Mexico on February   6 but all the model data clearly shows some sort of ridge developing bother just off the SE Coast.  This is strongly implies   that this coastal Low will track On the coast.  In addition because of the +NAO   there is no cold air to work over the northeast or Middle Atlantic states.  So the odds strongly favor rain with this next system  for     all of  NC   and central / eastern VA and MD. Areas of western Virginia and western Maryland could see a decent snowfall from the system.

By day 9  and day 10 we have another powerful system developing over the central portion of the nation coming out of the Rockies.  In fact the pattern development of the system  FEB  8-9 resembles a the the current system about to form in a lot of ways.  This is more a strong indication that we are now moving into a pattern that favors   Midwest  and this  new winter  pattern  may last for  most of February and March.  


1600 EST   JAN 27

I  never thought I   would  actually get around to saying something like this during the winter season … but  I am  actually getting a   LITTLE   tired and run down from the constant parade of major  eastern  US winter storms which seemed to be affecting so much of the country.  Fortunately  there appears to be a change coming  in  the pattern day after  February 4 or 5…  which may provide some of us tired and worn down weather folks with a break.
There  will be a complete rundown of the forecast and my analysis of the January  26   winter storm on the facebook/wxrisk   page under the discussion section later on today.  For the most part on extremely happy with my performance in the forecast that I start issuing back on January 22.  Overall   even thought  forecast was roundly attacked the criticize by many   weenies over at some of the weather forms …that forecast work out extremely well.  I do not believe that any of the forecast or forecaster had a band of 12 inch plus snows over the northeast   72 hrs  before the event   even began.   
I did.   Of   course my southwest VA  was a  disaster.
What is most interesting here is that even though the overall pattern across North America continues to not be favorable for  East coast winter storms…  we are  STILL   seeing East coast winter storms.  I presume by  now that many of you know that this   is  now   the snowiest January on record for Northern Virginia through the Washington, DC area up into Baltimore Philadelphia New Jersey New York Connecticut  Boston.
Here  in Richmond there has  been nothing.     I believe    that the January 26 event  was the 5 significant or major  East coast winter storm …and all of them have missed Richmond.     (OK the  Dec 26  event   gave    RIC  4″. Big  fooking deal).  And it is  true that only   with yesterday’s   storm  did    DC and Baltimore  see  a significant snow.      But that really is not relevant after the  two back to back blizzards those areas had last winter.     My point is that  is after  5   big East coast winter storms…  If you have  not gotten any significant snow…  and you keep missing it by just that much…  well you are probably screwed for the rest of the winter if you like snow.
The models are now coming into stronger  agreement and moved into  some kind of consensus here today with regard to the February 2 event.  This event I first mentioned  late last week– JAN 21 -22…  here on this website… in the newsletter and on the facebook site.
Additionally the European model from yesterday was showing this to be a Midwest winter storm with Low  pressure area developing over the Delta and tracking up into the eastern Great Lakes.     However the European ensemble from yesterday was much further to the east as was the Canadian model   — which by the way did a spectacular job with the January 26 winter storm!!!.   In addition the placement and size and intensity of the ridge on the West coast of North America does not support a Midwest track with this next system for February 2 .
Temperatures over the the Mid-Atlantic and the the New England regions are going to  run mild over the next few days.  That much is obvious and without any dispute whatsoever.
Second  we know that a strong arctic cold front with another massively cold arctic High is going plunging southward on January 30 -31.  The cold front will drive south and east reaching the east coast some time on the 31st.
 So far so good.  That   Low pressure is going to develop on the front summer over the central gulf coast– perhaps  over Louisiana …perhaps over southern  Mississippi or  Alabama.
For the Tennessee Valley and the Middle Atlantic states the key is going to be the timing.  Since we did not have a the blocking in the jet stream over Eastern Canada…  since we do not have a 50/50 Low…  and since we do not have any block over Greenland  ( -NAO) the arctic cold front is going to have to drive into the Middle Atlantic states first before the Low pressure area makes this move out of the gulf coast.
The model data today–  the 0z  and the 12z  Models  are  much more supportive of this idea that was yesterday.
Right now most the model data shows the cold front getting into Virginia and portions of North Carolina and Tennessee by JAN 31.  The issue then is how much cold air  will  get  into NC   and  VA?
If the cold air is shallow and not very deep …. then  when the Low  tracks northeast…  we would  be looking at  NOT snow but sleet and or freezing rain   over  NC and   much of  VA.    From Northern Virginia into DC and up into the I  95 corridor right now all the data clearly supports this next event is being another significant snowstorm. 
Based upon the data I am  seeing here at midday Folks  in Much of   western and  central and Northern North Carolina and    southwest    central and  south central Virginia  need to keep in mind the potential  exists for significant ice storm.
 POTENTIAL….  Keep that word in mind because we are not yet anywhere near making a solid forecast on this.
There are so many variables and things that can go wrong that it’s hard to make sure you cover all of them.
First we have to ensure that the cold front gets all the way into North Carolina Eastern Tennessee and Northern Georgia BEFORE  the Low comes out of the central gulf coast.
It’s possible that might not happen –which is what the data was showing yesterday. 
Another possible scenario is that the precipitation begins as freezing rain and or sleet in North Carolina and Virginia then quickly changes over to plain rain because the   Low pressure area tracks up into say West Virginia or Western Pennsylvania.  This type of track or scenario would also supportssnow going over to sleet and freezing rain from DCA northward into Boston.   
12z   EURO  FROM JAN 26   **  CLICK  ON ALL    IMAGES    FOR    FULL SIZE   ****

  0z EUROPEAN MODEL  JAN 27  run: the European model supports a significant  ice event for   western SC     southern NC and significant snow from Northern North Carolina and much of central and Southern Virginia.  As you can see the model develops a weak area of low pressure which moves off the South Carolina North Carolina Coast  in a  ENE  direction.
 0Z  JAN 27 EUROPEAN  ENSEMBLES:   had a the stronger low pressure area which develops over Southern Mississippi…  And the model shows significant colder damning over  Northern North Carolina and all of Virginia.  The Low  tracks  Northeast   just east of the  Appalachian mountains over the  coastal Plains –   say   Atlanta  to  Binghamton- Concord .    
0Z  JAN 27   GFS…  This first image represents the jet stream maps– the TOP   image   the   afternoon of February 1 the bottom image February 2.  I have highlighted the  PJ –polar  Jet stream  in BLUE  shading  and the    STJ –  southern Jet stream  m in RED.    And I have   drawn  in  a red circle round that is going to causes  the area of Low pressure to develop.
Here is the corresponding surface map which shows the low pressure development and its track according to the  0z  JAN 27 GFS run.  This looks to be ideal track for significant ice and snow for western North Carolina and Virginia  as well as  WVA  and MD.   In addition the 850 Low  track   over central  TN  looks  ideal for   snow and ice   KY    WVA  VA  and MD.
6Z GFS  JAN 27  RUN …   the 6z GFS continue to show an impressive looking setup for the Tennessee Valley and the Middle Atlantic states.  The Model held onto the significant piece of energy in the jet stream  — the  short  wave and its  embedded   vort max –   the  Model  was still developing the   Low over the  SE states  along with  some cold air damming indications.   According to the model all of Virginia days cold enough for snow and ice …even for Hampton roads.
12Z JAN 27  GFS   run:  continue to show a pretty good looking setup with respect to the Tennessee Valley and the lower half of the middle Atlantic states.   The Model was building a second or BABY  High extending off the main arctic High over Texas and Oklahoma.  The BABY High  located over  western New England  kept the cold air in place   into all  of the Middle Atlantic states  and into   western  Northern Georgia and the western Carolinas.  The model shows a very strong cold air damming signature…  With significant precipitation of overrunning Kentucky   WVA and  VA    and  850 temps  still cold enough to support significant snow over  northern KY   the northern half of WVA  and    Northern half VA…. with  RIC sitting right on the edge of the snow sleet line.
  This Next image –156 –   shows the  Low  tracking  ENE  into Northeast North Carolina or extreme far Southeast Virginia.  Inland temperatures are still at or below 32°so a large portion the precipitation   -based upon what this run of the GFS  is showing -would be a heavy snow or ice over much of WVA   VA  and MD. 
This image shows  total Precip– which as you can see the is well over a inch across much of the Tennessee Valley and the Middle Atlantic states. 
 12Z     CMC  JAN 27  run:  shows a Midwest track.  Now the model does have a BABY    cold High over New England which does set up a cold air damming and potential ice event     for   western NC  much  of VA and MD….  But the model takes the major low up thru or just to the west of the Appalachians.  This would drive warm air all away into the New England  states … so   any   ice or snow would change over to rain and temperatures and warm up significantly.  
 THE  BRITISH   MODEL.  The 0z and  12z  Model  runs  BOTH  show a   major Low coming out of the western Gulf of Mexico and hammering the Midwest with a tremendous amount of snow over the upper Mississippi Valley including Chicago and St. Louis.
  12Z  JAN 27  EUROPEAN  run: again the model is to the south and east  matches the  0z  run and the  6z and 12z GFS.  The model clearly shows the first cold front moving into the southeastern states and some sort of wedge of cold air settling Ian over North Carolina and Virginia on February 1. 
 The Low  develops over southwestern Georgia— a classic MILLER  A    set up.  Since the model has the arctic   High   plunging south from North Dakota into Western Kansas…  the cold air push over the northeast is not as strong.  If this depiction of the actual surface features   is  correct ….then the north winds coming out of New England and the Great Lakes will drive low level cold air into North Carolina and Virginia     WHILE  the Low  is   coming  up from  GA.    The upper levels of the atmosphere    over  NC   VA and eastern  MD  would still be too warm  for snow but the lowest few  thousand feet would be very cold   due to the  Low level North winds and this would support a significance for  SLEET   and  or freezing rain   == Ice  storm.
12Z EURO  ENSEMBLES….  makes sense.   There isn’t a reason  for this Low  to go to the coast   south of DCA.   The wedge is  pretty impressive    so this  is showing a    decent    THREAT  of  ice  over   NC and VA
SUMMARY : even though the   12z  EURO  and   6z and 12z GFS  have both shifted the track of the southern Low   well to the south and east …  In my view the overall pattern over Eastern North America does not support a coastal track.     However the air mass this coming in on January 31 is extremely cold and all the models do show the development of this  BABY  HIGH over New England as the southern Low  begins to develop.   This combined  with the  12z  European ensemble  which continues to show a  inland  track…  with this system for February 2. 
On the other hand the atmosphere   IS going be a lot colder in this event at the start of it ….than this what we saw for January 26.  
One last note….  The data is becoming pretty strong that the persistently cold  overall pattern across North America especially eastern Rockies is about to come to  end.
If you recall this image earlier in the discussion  you  will note that the PV  can be seen over Eastern Canada.  As long as that feature stays over  Eastern Canada   the mean trough will stay over the East coast and the pattern will stay quite cold .
But most of the model data continues to show that the   PV will slide east towards Greenland .  Not only does that constitute a very strong  POSITIVE  NAO but it takes the heart of the cold air off the East coast because it pulls the mean trough position  off the East coast into the Western Atlantic Ocean as well.  Assuming that this is correct… once the   PV  is located over Greenland and the entire pattern across North America will begin to relax and the cold air flow will be cut off from entering the country…  and a significantly milder pattern will develop over all of the CONUS  (after FEB 4).



Posted by wxrisk | GENERAL | Tuesday 25 January 2011 4:15 pm

1600   EST    JAN 25

click on image to  see  full map….     NE map out  at 1pm




0845 AM EST   JAN  24

Finally last night the wretchedly bad an awful weather model which is called the GFS got a clue. Where as Sunday afternoon of the model had no significant precipitation – over 0.25″ — in DCA PHL BWI NYC CT or BOS,… the 0z and 6z now does.

Whereas Sunday afternoon the 12z GFS  model had the  Low for Wednesday morning 100+ miles se of Cape Hatteras… the 00z GFS ( and 6z ) now have the Low further to the north by 200 miles.

 Whereas yesterday the12Z and 18z   GFS model showed the cold air holding and that most the precipitation in the northeast would be light it also fall as snow… the 0z and 6z now drives the the 850 low deep into coastal areas of the Middle Atlantic states and force the rain snow line well to the North and West of the big cities of I95.

This is why most of the forecasts and forecasters for Western Virginia have not had any snow in the Shenandoah Valley region for late Tuesday and Wednesday.  The   ass worshipping of this terrible  Model    has really gotta  stop.

It needs to be pointed out that even though the 0z GFS and 6z GFS finally has a clue of the correct solution … the correct solution has been shown consistently every day on   every run of the European British any Canadian weather models models. And yet for the most part meteorologists up and down the East coast have stayed heavily focused on the GFS and have ignored the these models showing the inland track of this coastal Low.

It is   beyond  absurd  that a professional meteorologist could ignore all the consistent data from these global models over the last four days but then become fixated or latched onto with the latest run of the 18Z NAM AT 72 HRS hrs is showing… or the latest run of the 18z GFS.

click on images  for  FULL size



2330  EST  JAN 22 




1830  EST   JAN 21

In the previous post I stated quite strongly that ….because of the upper patterns are  NOT    favorable for an East coast snowstorm …even though the model data on Wednesday strongly supported the significant snow event for North Carolina and Virginia January 24 – 25… I was remaining very skeptical.     Clearly the data today the supports that skepticism.

Now If you are into snowstorms  in the Northeast US… from  VA  to    Maine ….and you do not have this book then you probablye are missing out on a lot of useful information which can “feed”  your snow addiction.    

   http://www.amazon.com/Northeast-Snowstorms-1-2-Set/dp/1878220640       Now as impressive as that 2  volume  book  is keep in mind that that  this  is  third version or upgrade of the book .  The original version was a detailed 2 volume monograph  which came   in 1987…. and I have    copy as  well.

What  even is more impressive about this 3rd edition of the book is that there is a whole section on    “near miss snowstorms”   and this is important because if you don’t study them as much as I do … then  you will  not see or detect the subtle differences in the atmosphere large scale patterns.

Now keep in mind what we  are talking about here are big East coast snowstorms.  We  are NOT  talking about moderate events or  overrunning snows.   We are  talking about a  specific type of winter storm–  the nor’easter.  We are talking about the DEC 25-26  2010    FEB   5-6  2010…. FEB  8-8    2010… DEC 30 2000…. JAN 5-7  1996     JAN 25  2000    just to name a few so you get an idea of what we Are talking about.

In every instance…..  Without exception…  There are certain features in the upper levels of the atmosphere over North America    that  exist   when we have had these  big   NE  snow storms develop  the way   they  did.  Think about that for second.  Do you realize how  rare  that it is in the weather business to say   in every instance without exception?

As I stated several times both here and over the facebook page…  if you have   recently discovered  WXRISK.COM  and   DT….. you may have the impression that I    have this     “PRO  snow “  bias .  You  may to hold the view that I have a tendency to exaggerate  or  hype    snowstorms in  VA    NC  MD DE.       The problem  is that  such an impression only comes about because you have recently discovered this website .  You  may not have been  around  earlier in the decade.       Back then I     consistently downplayed   the potential for significant snow events several days out…  and I had developed a reputation of being      “ANTI SNOW”.

No seriously.     The point is that I had been doing this now for 10 plus years and if you were  not around  before 2009 then  your impression is somewhat distorted.

What  I try and do is walk a fine line between being skeptical and cynical.  For most of the last 10 years the snow drought over central Virginia has given many of us reason to be skeptical about forecasting any sort of major snow .

Last winter when I nailed the two big early snow storms with perfect forecast five  and six days out …  I can tell you for a fact   that  ALL  the other meteorologists in central and aouthern Virginia saw the exact same data that I did.  But it  had been so long since we   have seen in a major snow   in   central VA…  It is only natural to become skeptical and a little cynical. 

To be cynical is to deny the data   even when it is staring you right in front of  your  face.  But it also has to work both ways.
If you recognize and understand the patterns which bring about east coast snowstorms and you also recognize that if you don’t have those features and place it really does not matter what the model is showing you  are not gonna get the big  snowstorm. 

In the 33 the snowstorm case studies  in the   KU  book…  now  36  cases and   growing… 31  of the 33   all featured the cold arctic   HIGH  being  located no further to the east than 75° W longitude in the 24 hours leading up to the beginning of the storm on the East coast.

In this upcoming event  the    arctic cold High pressure area is already at  75 degrees W longitude when the storm begins to develop on the East coast.   Now if     had some sort of large system over southeastern Canada ….that would slow the movement of the the large cold High  over Maine and southern Quebec Canada… and  keep the cold air in place .  But that isn’t the case and as a result… this  High   is going to  slide  east and move  off the coast.

But there  is far more concerns to the    “all snow”     idea  than just that problem.     If you recall  the   Model data earlier in the week… it looked like    this was going to be a January 24 25 event.  Clearly that is not correct as the data this afternoon and early this morning shows this will be mostly a January 25 – 26 event.  This delay  it also hurts the cold air supply over the  Northeast  US and allows  cold High to slide  further to the  East  and in turn allows for the coastal Low to  come inland.

The model had shifted the track of the entire system inland significantly because the model shows the two pieces of energy beginning to merge or phase much sooner than what it was showing earlier in the week.  For this reason the model is developing the the coastal low much further inland and significantly deeper.  Recall that the the early idea of this being a significant snow and ice event was based upon the coastal low being very weak…1012    to 1016  mb.  As you can see the the European model early this morning develops 1005 Mb  Low Located near Charleston SC  which rapidly deep and some tracks over central  and  eastern NC eastern VA  and can be found over the lower MD eastern shore   by JAN 26 .

This of course was a significant change from what the data was showing earlier.  Yet all the other  medium range weather models   –  and the Canadian and the GFS — showed a significant track shift to inland early Friday morning.   So  it became very important to see if the ensemble data from the various models was supporting this shift inland.    As you can see the European ensemble   was somewhat further inland but not  dramatically so.


Here is the  12z European model.  The   important  thing to note here is that on January 25 the Low is  still down over the Delta  even thought the cold air is still entrenched over the NE US.   But this delay is costly because 12 hours later as the Low is rapidly intensify and moving into central NC  and VA  the large cold arctic High  is now much further to the east…  So the cold air wage over the northeast us is rapidly diminishing.  But in addition with the LOW….    THIS  strong…. and the    HIGH  moving out to sea  the   winds are now clearly   SE   over    VA    MD   DE   and southern NJ.  Turn it drives the warm air over the eastern   NC and se  VA  deep into   the Middle Atlantic states ….  And while we have is snow rapidly changing over to heavy rain….  for all of VA  and   NC  except for the far western portions.   The Low tracks   through     or over  NJ which would imply a significant change or mix from snow to rain   over  NJ  NYC  Long Island.

This scenario is strongly supported by the new 12z European ensemble mean  which supports the major coastal Low tracking well inland.  As you can see  as of January 26   the   Euro ensemble has the Low over Richmond and the rain snow line is north of DC  into  PHL and   southern NJ.   Again the   winds over  the   Northeast along the coast….  EAST or  SE  even into  CT.

Here is the  12z  the Canadian model and we can see the same sort of development with the overall pattern.    At day 4  JAN  25….  there are two pieces of energy which you can see  as   two blue lines in the Jet stream.    By day  5…JAN 26  the  two pieces of energy merge into one big system  that develops into a negative tilt… (  NW to SE).  This is a  sign that meteorologists look for which show rapid intensification of  surface Low pressure areas…  And in this case it mains that the low pressure area is not going to develop on the coast but over Georgia.   This is in strong agreement with the European models.   The 12z  CMC   argues that  eastern  and/ or coastal  New England   would go over to rain at some  point.   


 THE  12Z  UKMET — it is very close to the European and the Canadian solution.  Again we have two pieces of energy which are beginning to merge January 24 – 25.    By Jan 26 we can see both blue lines are coming together and developing that made itself or tomato alignment over the Mississippi River Valley.    For East coast snowstorm lovers that is simply the developing too far to the west too quickly …. and  we can see the   Low  developing rapidly over Southern Alabama.   The low moves northward up the coast so that by January 27    it is located over New England .   The  12z  Ukmet argues  that   much of coastal  New England  would Mix or  go over to  Rain  for a period. 

 DT   …WHAT THE 18Z  GFS?    It is all snow   –  or mostly     snow Man!

No it isnt.  The 18z   GFS  has the same  problen that the     12z  GFS  has.   One  the Model is a piece of crap.  Two …it  has a serious   flaw in its solution.


Yes of course the weather models can and probably will shift the track of the surface  Llow to the east somewhat over the next couple of days.  But that really is not the point.
If that is what    you  are focused   on….  then you are not understanding what’s going on.  Weather models   reflect the atmosphere  .  They dont have  Magical Power   that     cause weather systems   …  the Lows  and Highs  and  ridge and troughs … to move. 

 There  IS  a  reason why   there seems to have been this eastward bias with several of the winter storms since early December along the East coast. It was not  because of magic    or   because the snow weenies were praying to god   every   5 or 10  minutes.        It was due to intense large scale blocking in the jet stream which had developed over Greenland Eastern Canada and southeastern Canada in the period from December 1 through January 10.

That was the mechanism or reason why the storms  these  coastal  Lows  were bending to the right or somewhat to the east as they came up the coast.  That is now gone and because ith as faded away from the patterns over North America and the Northern Atlantic Ocean ….that tendency to shift to the right on the models as we get closer to the storm  is disappearing.

Consider the last two runs of the Canadian and the European model.    Those models have shifted west…. NOT  east.  And more importantly the Canadian and European ensemble mean maps   have also shifted WAAAAAY to the West.      That may be the first time we have seen that in the model trends since December 1.

SUMMARY        This appears to me  to be a  classic   I-81 SNOWSTORM  IN  NC and    VA.     IF the snow starts   early enough      SOME   snow could    fall over  central     VA.   I reject the coastal Low   track of the GFS  Model becauase      the GFS   this far out is a  piece of  crap  with   East coast   winter  storms.       Given is   TERRIBLE   track record past  the    84 hour time  frame   with East coast  winter  storms ….   the  odds   and the PATTERN   strongly  support   the
0z   EURO  ….
the  0z  EURO    ensemble…
the    12 z  Euro 
the 12z  Euro ensemble 
the   0z    Canadian 
the  12z  Canadian  
the 0z Ukmet
and the  12z  Ukmet  ….solutions  
over the  Pitiful   18z  GFS.  

  I see   DCA  and   BWI   changing over the Rain…  for  some  period  of time.     Heavy snow  may    fall there before   the change.  Frederick  and  Leesburg    could  stay all snow.    This also applies to    southern NJ and  Philly…  NYC    Long Island … MAYBE   coastal   CT….  and   southeast Mass.   Again  the 18z GFS  JAN 21   RUN   is  seriously  flawed and    not  good  enough  to  blow    my snot on. 

JAN 21-22-23 THREAT ? The Big fizzzle

Posted by wxrisk | GENERAL | Wednesday 19 January 2011 5:41 pm

1515  EST   19 JAN
This whole event for the weekend is turning out vastly different from what I thought was going to happen over the past weekend–  that is to  say JAN  15-16.  Recall or read read the post below from a afternoon of the 16th the the scenario which I was considering was that the cold front which sweeps through the east coast first…. on JAN 20… then  when the front stalled a second piece of energy would interact along the front …  and develop a second larger coastal Low   for  at least some portion of the Middle Atlantic Coast and possibly into New England JAN 22-23.

Since that posting   obviously a whole lot of data has come out and this scenario is no longer viable.  The first change has to do with the cold front.  It still going to come through on the 20th  or 21st but the the Low pressure area is going to develop on the cold front BEFORE or just as   the front is  reaching the the Middle Atlantic states.  This greatly reduces the  chance  if seeing ANY accumulating snow over Central  … southwest   and    eastern Virginia.

Another  reason is that ahead of the cold front we  have  a pretty mild air mass.  Temperatures have surged into the 50s  across the Middle Atlantic states   this afternoon…  (which oddly enough  is exactly what I  have been forecasting from last week to my private clients even though the  GFS  MOS  guidance only supported temperatures in the lower to Midddle  40s.)  With SW winds coming in a head of the cold front tomorrow and mild temperatures currently in place any precipitation is going to fall over Central Virginia will be rain which might and as wet snow.

Now once   the  surface Low begins to rapidly develop it will  pull in colder air so that the mixture of rain / snow over the Washington, DC area were quickly change over to  snow  in Northern Virginia as well as DCA and into  Baltimore.  If the cold air gets into   the  Northern VA DCA the metro area in time …a few inches of snow could fall.

It is important to keep in mind that this is a fast moving cold front and the Low pressure area is going to zip rapidly through the  East coast.  This is one of the reasons why I am not forecasting significant snow amounts over the big cities of I95 from Philadelphia to Boston.   Another  main reason has to do with the storm track.  I  am not sure if the Low was going to pass close enough  to those  I-95  big cities  or develop into a significant system   that  drives heavy snow into  Philly  NYC   Northern NJ  CT and Boston    (Not  NO snow… heavy snow …   over  6″).

Beyond this event the models continue to show a strong piece of energy into southern Jet stream    that is going to develop a significant coastal Low over Georgia on January 22.  So in that regard the European model has gotten at least some of the general features of the pattern correct.  We   can  see the significant  Low pressure area off  the southeast coast here.    It is  THIS feature that the models were    focusing on last weekend for a possible significant East coast winter storm.

What  is killing the second storm– the Low off the GA coast on JAN 22  —from coming up the coast   is a another piece of energy in the Jet stream  that is diving SE from the central Rockies chords the lower Plains.  In the old days this feature would be called   “a kicker” because it drives the main piece of energy the or shortwave over the Georgia Coast EAST and out to sea.

Taking a look at the larger picture one of the reasons perhaps the primary reason why the big storm scenario   for JAN 22-23 which the models were forecasting on January 15-16… is not going to verify has to do with the overall pattern which is change significantly in the past seven days.

The High latitude blocking over Eastern Canada and Greenland is no longer there. And   NO model data of any kind  on the Morning   or   afternoon  cycles  shows any hint of this feature coming back before the end the month.  This has a profound impact on the overall pattern.  In some of the the weather forms which are out there on the Internet you will come  across some  Ignorant  weenie tried to argue that we don’t need to have high latitude blocking in place for east coast snowstorm patterns.

Not only is that not true but the Ignorant weenies  deliberately distort   the premise into something which is not     relevant.    The research and data is clear that at the time of the Noreaster  hitting the East coast we do not have to have a block over Greenland Eastern Canada  –    known as the      -NAO.      The issue  is getting the pattern to set up so that the coastal low becomes a snowstorm  and NOT a rain storm or Midwest storm.

The high latitude blocking which develops over Canada and eastern Greenland    the  -NAO…  affects the pattern in many different ways   when one is considering the potential for East coast winter storm.

In the days leading up to a  possible  East coast winter  storm…  the  blocking  often causes Low pressure  areas over  southeast   Canada to get  “trapped”    over   or close to  the New Foundland Canada.  This feature in the weather business is referred  to as a  NF  LOW or a  50/50  Low….(50° N latitude 50° W longitude ).       The combination of the blocking feature over Eastern Canada and Greenland   and the  50/50 Low  means  that the large cold arctic High which settles in over the Great Lakes and /or  New England stays in position and is not able to slide off the coast.  This means that the cold air stays in place over the northeast from North Carolina to Maine .

Without the blocking features over Canada and without the 50/50  Low  the  cold High  pressure  ares  do  not stay in postion   long enough to ensure an all snow event for the   coastal  Plains — from  Raleigh  to  Boston).  Now obviously the impact of the large cold High in position is much more important for locations such as Raleigh NC and Richmond VA   than it is  for  Boston and  New  England.

We can see the impact of this with the next potential event on January 25 – 26.      Looking at the weather maps initially on January 24  25 from the various weather models it would seem to be ideal or pretty close to ideal for a significant East coast winter storm to occur.

However all the models showed that the large cold High slides off the coast rapidly once the coastal low begins to develop.     Why does this happen?    There  is NO  50/50 Low and   No  Blocking over    eastern  Canada and / or Greeland  so there is No actual mechanism in the atmosphere to keep the cold High in place over the Great Lakes/ southern Canada  and or  northern New England.

But even besides all that… the blocking patterns are what good  meteorologists   look at  to see  if the   pattern is    ” setting  up”     for East  coast winter storms has further implications.

The jet stream maps from the various global weather models such as the European the Canadian and the GFS all show   at the surface low on January 25 it is going to come inland and track along the coast or very close to it.

Some of you may already be wondering if it  is possible that this Low  could be  shift its   track to the East a couple  of Hundred miles?   This is where the blocking patterns that we look for come  into play because   IF we had those features in existence over Eastern Canada and Greenland…  that any shift to the east would be favored.

Instead what we have is the merging or Phasing  of the    Two Pieces of energy  into one  BIG  trough over the  Midwest   because of    the lack of Blocking .

If we had the blocking over Eastern Canada and Greenland   then this phasing  of the  2 pieces   of  energy would  occur   East of the Mississippi river and this in turn would favor  the coastal Low  on JAN 25-26 tracking more to the east and thus increasing the chances of late all snow event.

But since we don’t have any that blocking —the phasing between the two pieces of energy  — occurs of much sooner  ( WEST  of the Mississippi River)    which  is    the  kiss of death sign for those wanting were or hoping for an all snow event on the East Coast.

Looking out to day 10  we  see   some HINTS  that  a  New  MIGHT  be forming  over    Iceland and the  UK.  WE  can  clearly see  significant  heights    building in the Jet stream.   often… but not alwways… when this happens  the Block  will retogreade into  Greenland.   So far NONE of the    11-15  day ensemble   are showing  this.  


1955   EST    JAN  16

Well it’s time to start talking about the next significant winter threat for the East coast.  And by that I am  not talking about the the January 18 event since that is a whole bunch of nothing.  Sure the precipitation still might start off as snow from   PHL to Boston but it IS   going to change over to rain on southeasterly winds… low level warming  temperatures  both at the surface  and all the way  to  850 mb.  Now some of you may look at the surface map from our morning or tomorrow evening and see this large cold High centered over southeastern Canada and wonder why  or how can the cold air possibly not hold in place   as the  southern Low  comes up the coast.

The first reason is that we don’t have any feature over southeastern Canada to  cause the the cold High to slowdown.  So it is  going to keep on moving rapidly to the east.  But in addition the event on Tuesday is going to consist of two areas of Low pressure–   one over the  Great Lakes and the   southern  Low  (which we can see the heavy showers and thunderstorms over the delta region this evening).     It is the “attack”  of  both  of these Lows which will help rapidly wrote the cold air just as the precipitation begins to move surge northward.   850 MB temps will  warm   to +3c  or warmer   even over  eastern  and southern New England.    In addition if you look at the   RH (relative humidity)   fields on the walk short range weather models you  will notice that there is large gaps in the precipitation coverage over  VA MD  and south  central  PA.

The main issue of concern and focused  from MY which really is on the   THREAT  of  significant  winter storm threat   for  JAN 21-22-23.

THREAT… not   yet a   fact or a  forecast

Once again we have the European models which had been the most bullish and aggressive on this feature and have shown the coastal development of some type on the cold front  for the past 7  runs.  And not surprisingly the operational GFS has been showing no such event of any kind –until early this morning and midday today.  And   the  Canadian model has been hinting at some sort of system developing on the cold front over the southeastern states  since Saturday.

Essentially what we are looking at are two possible scenarios.   The   new  strong cold front will drive through the Midwest into the Middle Atlantic states on January 20.  The front should drive fairly deep into the Tennessee Valley and the southeastern states by the morning of the 21st.  Arctic High pressure will move into position over Montreal.

At that point some sort of wave of Low pressure will develop on the front over the southeast states.  The interaction between the large cold High to the north and  this Low will set the stage for a classic cold air damming   event.

This image will show you what a COLD AIR  DAMMING event looks like on the weather maps and weather models.

We can see the   the  numerous thick   Black Lines  over  VC  NC  MD PA   NJ  having this funny  bend of  ” kink” in them.  The  appearance of   CAD is often but not always a sign of a significant winter storm developing but it does not tell us which areas could see the the significant snow and ice .   Many years ago weather models consistently over warmed the atmosphere at low levels during East coast storms and would prematurely forecast   a changeover from snow to rain.      However once the the phenomenon known as CAD was identified …meterologists were able to see this very clearly and the winter forecasts became a lot better when  it  ame to winter storms along the East coast.


The last few runs of the regular or operational European model has been developing Low pressure over Georgia…  which moves to Eastern North Carolina on JAN 22 then   undergoes rapid intensification as a tracks off the southeast coast of New England.  In this sort of scenario  the model  has heavy ice over  northeast GA  western SC    much of NC  and   snow  from   VA to  southern Maine — including the big cities of the I   95 corridor.

The FLAT WAVE  SCENARIO  is supported by most of the other model data including the European ensemble . In this   set up a wet but rather flat looking Low pressure area develops  over the southeastern states and then tracks  ENE off the North Carolina Coast out to sea.

The following Models  support this   scenario.




In  this particular scenario only North Carolina and Virginia would see significant snow and ice.  The precipitation would probably start off as ICE  then changeover to snow and   probably  no significant  snow  from DC northward.

Given the number of big storms which is hammered the Northeast US this winter  it is  easy to assume  that the big  East coast winter storm  scenrio #1 is probably going to turn out to be orrect .  And of course given the seasonal trend it’s hard to argue against that   the  BIG   East coast winter  storm idea.   But if we decide to use science as opposed to   weenie wishcasting…      the  last 3 big East coast winter storms have all occured with strong High latitude blocking over Eastern Canada and Greenland     (a  strong  negative phase of the NAO) .  That is clearly not going to be the case this time around and certainly not by January 20-21-22.

On the other hand if we do  end up getting   the  flat wave of Low pressure   scenario    then   there  COULD  be a problem with that northern extent of the precipitation.  We could end up seeing significant snow and ice storm over   NC and  only the  southern half  VA….  with very little winter precipitation falling north of Fredericksburg.

Right now I do not have a particular favorite— I am not biased towards one  scenario  or another one.  The change in the pattern in the jet stream over the Eastern Canada and Greenland should be significant in my opinion  so  as  to favor the flatter weaker way of scenario affecting only the Virginia North Carolina this coming weekend .

But on the other hand it sure is hard to ignore the seasonal trend which has been for big snow storms and the northeast US.


Posted by wxrisk | GENERAL | Saturday 15 January 2011 1:57 pm

1145  EST   15 JAN

The   FIRST  issue   we have to deal wth is  in the short term and wave of Low pressure which is going to develop on the cold front on the 17th and 18th as it moves through the Midwest and towards the East coast.  Although this is going to be primarily a rain event for the  Ohio valley  and all of the Deep South…  from Virginia and northward into the big cities of I 95 –there  is  some uncertainty as to the precipitation type and how long frozen precipitation is going to last before changes over    to rain.

All the models agree   that at 60 hours  — the afternoon of the 17th –there going to be two areas of Low pressure over the middle portion of the country.  One will be  the   Great Lakes and the other over the Delta.  Originally it looked like the southern Low was going to track  up the Appalachians  or just west of it ….which would ensure that most of the precipitation  (even into southeastern New England )   would fall as rain or snow rapidly changing over to rain.  However the new model data is showing the southern Low developing a bit stronger and tracking much further to the east.    The  Oz  GFS  the 6z GFS and the 0z   EURO a fairly strongly with the coastal low taking over by the inning of the 18th .

Complicating this even further it is the arrival the fresh cold area of High pressure on Sunday and Monday across the Great Lakes and into New England.  If the  cold HIGH was to stay locked in over the Northeast ….then this event could be a lot more snow and sleet then rain for anybody from Virginia to Maine but that is not going to happen.

There is no blocking feature in the jet stream over Eastern Canada and / or Greenland and there  is no  Low  either at the surface or in the upper levels over southeastern Canada.  This means that the cold High   IS going to slide off the New  England coast  so winds will NOT  stay NE  but  turn  to a  East  direction.    This in turn  means the cold air   over the  coastal  Plains of the  NE will get  eaten away.

   For the Great lakes and the northern portions of the Ohio Valley   and for the interior portions of the Northeast …such as   western and central PA and NY this will be primarily a snow going over to sleet event and significant accumulations are likely . 

However  for the NE  quadrant of the nation — Maine to   Virginia –the key is going to be the timing and arrival of the precipitation over the Northeast.  IF the precipitation begins early enough that it will start as snow or sleet over  western  VA    and MD.  It  MIGHT  begin as frozen precipitation over   central and eastern VA and   eastern  MD but it should quickly change over to rain there.   But  over  WVA   western  1/3 of  VA    western  third of MD  significant snow  & ice   is a  real possibility especially if the  Cold High    manges to  keep the  WEDGE of cold air  in place   over the    VA Piedmont.  

For the big cities of I95  –  DCA  to   BOS…  There is little doubt that the southern portion of the big cities   –  DCA  BWI  PHl  cities will change over to  sleet then rain.   However  over   NYC   CT and BOS more than half of the total precipitation may be either snow or sleet  with additional accumulations possible and the precipitation and being as rain .
Down the road the pattern shows more promise if you like cold weather and winter precipitation.  So far this winter  three  have been distinct blocking intervals  or  episodes in the atmosphere over the western hemisphere.    The Blocking has been the development of a bubble or block over Greenland which has retrograded — moved west and set of east– into Eastern Canada and then eventually into North Central Canada and then into Alaska. 

It is the   repeating     re-development of this block   which has caused the pattern to become  cold and stormy.   In the last two episodes of the blocking we saw two very distinct major East coast winter storms which  occurred as the blocking episodes were weakening or falling apart.  The first coastal storm was the December 25 – 26 nor’easter…  which is coming at the end of the very strong  2  week blocking episode which is falling apart over North Central Canada.    The second event was the January  10-12 coastal storm which was a major event from Alabama to Boston  — except for Central  and western Virginia  — which also a occurred as a intense blocking episode over Eastern Canada was coming to an end.

After the January 18 event the models all show a strong cold front which is going to drive deep into the Plains and into the Deep South.  The European model on Friday the January  14 develop significant low pressure on the front….  as  cold HIGH pressure  moved into Montreal and Vermont.  You can see what the model was showing here. 

  If the European model is correct it would be a major winter storm….  bringing possibly significant ice into Northern Georgia   northwest  SC    much of NC  and   snow  over  much  of  VA into  MD  southern WVA  DE and possibly into southern  PA and  southern NJ.   The 0z   SATURDAY   EURO    continues to show this event  for JAN   21-22.

0Z  EURO   ensembles

 The  12z GFS and GFS  ensemble from yesterday did not support this solution at all .  Those Models    show   just large cold arctic High dominating the weather east of the Rockies and especially Eastern Mississippi River.     And the 0z  SATURDAY and  6z GFS continue to show no such event of any kind around January   21-22.   Not surprisingly the  0z European and European   ensembles  continue to show a significant event .

Because this is a southern stream feature –that is to say the Low pressure area is a piece of energy in the southern jet stream which will be coming out of the Gulf coast or Delta region –  it is likely that the GFS  Models which do not handle southern features well at all ….will continue to not see the system until about 72 HRS before the event . 

Instead the 0z   GFS  has a major coastal event developing around January 25.  The model does this because it takes the blocking which develops east  of Greenland and pulls it back towards Greenland and then Northeast Canada.

Longer term the European model yesterday showed a the return of a massive blocking feature over Greenland.  This   would be in the fourth major episode of strong   Blocking   over Greenland   ( called  a -NAO  Iin the weather  biz)   and it’s not even February 1 yet.

The data this morning however is not quite as impressive with this potential blocking feature.  The European model shows the the strong block developing but has it east of Greenland closer towards  Iceland….  and this is supported by the  GFS and GFS ensemble.  


When   the blocking develops east of Grenland  — is called   EAST BASED  – NAO.   When the blocking is over Greenland or northeastern Canada it  is  referred to   in the  weather    biz as a   WEST BASED  -NAO.      Got it?


If you like big East coast snowstorms then  you  want  a  good strong   -NAO   feature to help set up the overall winter pattern in the jet stream.  However there is a difference as to the favorability of a  EAST BASED -NAO  vs  WEST BASED -NAO.    The western -NAO there is the entire East coast   (see DEC  25-26  and JAN   11-12)     whereas as a   eastern based -NAO   favors  NYC  to BOS.

At this Point I believe that even if we do end up seeing a  east  BASED   -NAO  initially did well retrograted back in court Greenland and northeastern Canada before the end of the month which will set up another stormy episode for the eastern third of the  Conus.


Posted by wxrisk | GENERAL | Wednesday 12 January 2011 10:05 pm

1800  JAN 12

This image shows the actual snowfall cover across the U.S. as of JAN 12.     ***  CLICK  ON ALL   IMAGES   TO   SEE   THE FULL  SIZE   !!  *****


You can see very noticeable hole which exists over much of the commonwealth with regard to snowfall and you can also see that much of the Deep South is currently under an extremely heavy snowfall cover… relatively speaking. I began forecasting the JAN 10-11-12 event well before JAN 1 but of course from that vantage point ….and up until the last few days of the forecast …I could not anticipate that so much of Virginia as well as the Washington, DC area which sees such little snowfall. Thus your perspective and judgment as to whether not I got this event forecasted correctly depends on your perception about what makes good forecast.

IF it is all about how much snow you got in your backyard… then this was not a great forecast if you lived in central western or northern VA and the DC metro areas. I did not back off the significant snowfall cumulation until Sunday night and early Monday. To be sure it would of been ideal IF I was able to anticipate the snow gap over the commonwealth from several days out …. and never forecasted 3-6″ and 4-8″ form late last week as a possible snowfall. That being said I do think seeing the trend and backing off of the significant snowfall idea 36 HRS before the event beagn is still a pretty good forecast. But again that is up to you.

If you take a bigger perspective seeing all this heavy snow from Arkansas to Boston– except for Central Virginia– is a very good forecast given that the initial forecast as a possible significant winter storm was made it 10 days before the event.

Ok on to new things.

There are increasing signs that there is gonna be another significant winter storm threat for the northeast US…  But not for most of the commonwealth or North Carolina where this event looks like it will be rain.    The Issue  at hand  is  the I-95  corridor  OR will  be   and Inland  snow event and  rain  ( or snow/ rain mix)    in the BIG  I-95 cities.

One of the things that weather hobbyists have to keep in mind when they look at winter weather maps it is that just because you have the BIG “L” for Low pressure to your south… it does not mean it is going to snow (unless of course shore and Minnesota or the Dakotas or the northern Great Lakes). With this upcoming situation for JAN 18-19 we have to wait for cold front to pass through the East coast in order to establish of the cold air.

Before the cold front arrives HIGH pressure over the northeast US moves out to sea and the winds turn around to a southerly direction for much of the East coast and probably for most of the I- 95 cities.

We can see it this on the early morning European ensemble mean. The early Wednesday morning 0z European was suggesting that the northern half of VA MD southern PA and NJ could see a decednt snow fall out of this wave of Low pressure that develops on the front. However as you can see from this image the European ensemble mean has a much warmer set up with 850 temps well ABOVE zero from VA all the way to BOS. Thus this looks like in an Appalachian snowfall as opposed to anything for the northeast.

This idea and overall scenario is strongly supported by the 6z and 12z GFS and GFS ensemble…. NOT shown.

The 12z operational or regular European model continues the trend.
On the morning of January 17 we have a seasonally cold area of High pressure over Montreal with cold air driving into Central North Carolina and Low pressure is along the Louisiana Delta. But at day 7 the cold HIGH is slipping off the coast and the winds turn around to a more E or SE direction which allows for significant warming over central and eastern Virginia as well as most of North Carolina the lower Maryland Eastern shore up to Southern New Jersey. For inland the wedge of cold air still holds… so that the Low pressure area over the Carolina coast line could be delivering snow to western and Northern Virginia including the DC area and possible significant ice over the Piedmont. I don’t want to sound the alarm for possible ice storm over the Virginia Piedmont just yet but it certainly it is a threat. For central and Eastern Virgina this is purely a rain event that might begin as snow or sleet. At day 7…JAN 19 this storm rapidly deepen and bombs out over the northeast coast bringing widespread heavy snow to much of the northeast– including of course PHL NJ CT LI MASS NYC blah blah blah.


However the issue is not settled because the European ensemble is significantly warmer as it has the Low tracking much further inlandk. You can see that here. The cold air WEDGE is much different — really it is gone on the European ensemble mean… as the winds are out of the south or southeast up and down the entire I 95 coast from North Carolina to Boston. At day 7 the Low is on the Maine coast and I have seen the 156 hr euro ensemble mean Low position and it is well inland.

In other words the European ensemble mean argue strongly against as being a major snowstorm for the Big cities of the Northeast.

As we look at the the atmosphere to see the teleconnections the indices clearly show that the NAO which has been severely negative for most of the DEC and the first 10 days of January… is now shifted into the Positive phase. In other words there is no high latitude blocking over Greenland or Eastern Canada . It is this blocking in the jet stream which forces the jet stream over the US to come further south and in doing so brings the arctic air into the Northeast BEFORE the Low on the coast develops.

This is why having a sustained negative NAO feature is so important in the pattern leading up to a major NE US snowstorm. Of course that does not mean NO snow for the I-95 big cities and the -NAO does not really have an impact over the Appalachian and interior portions of the northeast with regard to heavy snow.

These two  images show the   500 MB  pattern   of the DEC  18-19   Low.   At Day 5   the  BLACK  lines hsow the   2  short waves or   pieces of energy in the  Jet stream… that will come together to make the Low   on JAN  18-19.  There is  one over the   Gulf and another  in the central Plains .     But at day 6  we can see these   two   features about to Merge…. into  one    BIG  system.  However  they  merge  too far to the West  for  NC and  VA and   eastern MD which    is why the Low  takes an inland track  through  VA.


 Beyond this event the pattern stays cold. The models clearly show a east decent size ridge developing over Western Canada and a pretty for large cold high dropping south. Nothing extreme mind you but certainly quite cold.

However again as we can see from the 12Z GFS and Euro ensembles…there is no sign of any sort of blocking developing over Greenland or Eastern Canada. So with ONLY a West coast ridge a deep trough gets established over the eastern Conus… but hte trough is broad or “U- shaped”. Any sort of Low pressure that might develop over the Gulf of Mexico region would stay weak and flat leaving the pattern essentially cold and dry.



Posted by wxrisk | GENERAL | Monday 10 January 2011 5:07 pm

1630  EST  JAN 10




The periods of the sun this afternoon over South Central Virginia when skies were supposed to be clouding up is a pretty troubling sign if you want significant winter precipitation in Central Virginia.

Once again the medium range models have done a fabulous job in showing the threat for major winter storm for the  East coast .   Yet for   some   reason which is really hard to explain….  everybody from Arkansas to Boston is going to have seen a significant winter storm    except for Central Virginia.  That is why all the TV stations last Friday and last Thursday talked about the threat for significant winter weather and snowfall for sept Virginia.  That is what I did was talk about this event since December 29.

There are two ways to look at this.     One is the unsophisticated  self  absorbed    way  which is  based on the   your  backyard.     If  the only thing that determines whether not the forecast from  10 days ago has turned out to be correct   is the amount of snow in your own backyard …  well then  THIS  forecast has busted    …  and   that is true   if and only if  you live  in central Virginia.    It does not matter    if it  has snowed  20 feet of snow from Atlanta to Boston.   If you have this  perspective and  YOU  don’t get the snow   then  nothing happened.

Or you can take the more sophisticated point of view and realize that for a long range forecast like this…       this has been an almost perfect forecast track …  except for a small portion of the  Middle Atlantic states known as Virginia. 

As I said on the web site in the discussion on Thursday or Friday  from  last week that in order to get the big snow in Central Virginia we had to keep the southern piece of energy strong.    This is the piece of energy which bought the 14″ snow to Huntsville Alabama…  Heavy snow and ice to Northern Mississippi  and Atlanta …    to northwest portions of South Carolina    and a  ice storm into Western and central North Carolina. 

Instead what has happened is that this  1st piece of energy  has collapsed completely…  But only just in time so that Central Virginia doesn’t get  decent snow. 

This sort of bizarre snowfall pattern which always manages to screw things up  over Central Virginia has gone on for more than a decade.  The top 10  LEAST  snowiest winter    at Richmond… going  back to  1887…  feature   3 of them  in the  decade  from 2000-2009  and  two more  at in the top 20.       Even last winter which many think was a fabulous winter in terms of snow in Richmond and Central Virginia…  was actually a series of  snowfall  that in every case   was the lowest   snow total   in   the   state.

This time around what is killing    this  event for Central Virginia is the fact that the precipitation reaches   the North Carolina Virginia State line around 7:00 PM this evening.  And then it sits there for next 12 hours taking all that time to move 70 miles to the north.     During that period a lot of the cold air currently over Central Virginia begins to fall apart so that once we begin snowing temperatures are are already close to freezing in the upper levels of the atmosphere.

By 1:00 PM the northern edge of the snow line will be very close to Fredericksburg Virginia.  Interestingly enough in the next 6 hours the snow line shifts and north from Fredericksburg to Philadelphia  a distance of 225 miles in 6 hours.

The question then becomes why does it take 12 hours for the  snow band  to advance 70 miles…   to move from the Virginia North Carolina State line to Richmond….  But it only takes SIX hours  to move from Fredericksburg to   Philly.?

Part of it has to do with the dry air but if that was all there was to this then the snow certainly would not advance into   Philly in 6 hours from Fredericksburg.     Clearly the  development of the  coastal Low  speeeds the snow   band growth   over    MD and DEL.      The best case scenario for Central Virginia would be for   3   or 4 inches of snow and that  is assuming that the snow comes in by 1:00 AM   and  that the sleet changeover is delayed a few hours. 

Barring that from happening the most amount of snow we can expect is   1-2   inches.  It is also quite possible that very little snow were sleet or any precipitation of any kind falls on Tuesday as there is a bunch of model data which shows a very dry air mass and no significant precipitation of any kind falling over the Piedmont or Central Virginia all day on Tuesday.

 Some will   make the argument– and some   meteorologist in fact  did   make this argument  on the facebook page   back on JAN 8–   that it is the dual low  structure… which often   means  much less snow than what the  Models   Originally are  depicting   for  Virginia.

  True….  up to a  certain point.  Dual Low    pressure  systems do NOT  bring 14″ of snow to  Huntsville  AL and  8″   + to the  Northern GA…  and 8″  over    northwest SC  and  snow and ice to Raleigh.       Ergo  if the   1sy    piece of energy in the southern Jet stream  did NOT  die      the snow would be   faitly  decent  in central VA.

 There are no  more snows  or winter    weather events   on the  Horizon    for the  next 7 days.

1130 am   9 JAN 


As you can see the  Bottom has fallen  out   with regards to central   VA    and especially the  Richmond   area.   AGAIN.



1500  EST  JAN 8


   I am clearly   going with the     last  few   runs of the    euro and euro ensembles   which have  really    been on a steady    TREND  of showing a  BIGGER Low  as  we get closer   to the   event and with MORE precip.    I   do not know what to  do with the   GGEM ( canadian) and GFS  models  since every other  run those  models  flip  flop.       In addition the    GFS ensembles  are clearly   showing  BIGGER  low  with  more precip   than the   operational  runs and looks more like        the  European  model .




Posted by wxrisk | GENERAL | Friday 7 January 2011 8:30 pm

1855  EST   7JAN

One of the things that I do differently and makes me  better  most other meteorologists on TV is that even when there  is no   a snowstorm coming I closely watched and follow weather models   beyond 48 hours.  Beyond three days…  Beyond six days   beyond 10 days.  All year  around.    But it is not just me– you will find this to be true with any energy or agricultural meteorologist because when you  are dealing with the timeframe is that we are dealing with you need every piece of inside information you can get.
There is a site on the Internet which you can access for free   run  by   NWS ‘s  department of environmental modeling center  ( EMC).  This department is responsible for developing maintaining and tracking all the various weather models that are used to see which weather model reforms the best and under what conditions. 
 It has long been known that the  18Z   GFS   run has been the most inaccurate and worst performer of the four   GFS Model   runs     ( 0z  6z  12z  and 18z).    Unfortunately  there are   TV meteorologists  out there… one of them  the Richmond…   that sees   the 18 Z   GFS  and has decided  for some incomprehensible reason …..that all the other data which came out today  that  showed significant snow coming for Central Virginia is now absolutely worthless.  This genius has decided to ditch all that the other   model data and use the 18Z  GFS   and thus   has lowered   his snow   numbers  to  wwell below   any other  Model Guidance  for  Tuesday Jan 11  event.
 It is clear that  he is unaware of how badly performing the 18z GFS  is.  That  much is   Obvious.  But there also seems to be a problem   with   the  reasoning.   Given that the event is still four days out why would any one throw out ALL the   other model data   today showing significant snowfall for Central Virginia and decide to go with one model which showed  much less snow?
The mind is simply boggles  by the  ahem reasoning.
We will start out by taking a look that the model data from early this morning.  Even though a lot of the model data on Thursday was pretty aggressive with the potential snow situation for Virginia and the Middle Atlantic states the European model was not.  The European model on    Tuesday  Wednesday and Thursday showed a flat wave of Low   with not a lot of development …moving off the Hatteras Coast with only a moderate amount of precipitation getting into Eastern Virginia.
And as I  have stated many times before…  The European model is the model choice for East coast winter storms   in the day  3  to day 8   range.
This image shows the shift in the European model which started this morning.  There are four maps the two top ones are the European  ensemble models .  It takes the Low pressure area of near the Savannah Coast moves up the Carolina Coast line then hooks  a right turn east of Norfolk.   The bottom 2  maps  are the 0z  JAN 7 GFS Ensemble  which show a similar pattern…  but here the   GFS is a little warmer over southeastern Virginia.   The 0z GFS   and  Canadian   had more  snow  and a Bigger Low further up the coast with up to an 10″ or  so of snow   over  DCA area.
 AT  12z  today the  GFS   however  backed off  that idea    as you can see  here.  The model shows a significant snow for west central and North Central North Carolina all of Virginia but especially central and eastern portions and the lower Maryland Eastern shore…  And like the European model insisted… hooks a  BIG right turn   out to sea.  This would mean that areas north end of DC into Boston would not see significant snowfall.
This image shows the precipitation forecast from the   12z GFS   Model.  As you can see the amounts are decent but not overwhelming…  And the dark blue band  gets into Richmond  and much of Eastern Virginia.
The reason why the  12 z GFS show this change  was  that  the Model  does NOT  have a   Upper Low  in the Jet stream forming  as the Low comes up the coast.
This image shows the overall jet stream pattern…  from the   12z GFS.  The blue circle shows the main piece of energy which is going to cause the low  pressure area to develop.  But as you can see it’s not closed off in the jet stream and   there fore  it is going to follow the blue arrow  and move off the Virginia Coast and take the low pressure area out to sea.
  IN    ORDER    TO     GET  A BIGGER  SNOWSTORM  FOR VA  MD   DCA  and into the Northeast   US…   we  HAVE     TO    GET  A    CLOSED     UPPER    LOW    IN THE    JET   TO FORM  AS THE    LOW COMES   UP THE    COAST.   
If that does not happen that what we are  looking at is a significant snowfall  But  not a major one. 
The   12z   Canadian model followed the same sort of development has the   GFS.  It no longer show to foot of snow over Washington DC Northern Virginia but instead had a band of moderate snow blowing across Kentucky West Virginia Virginia and Maryland… and the Low  taking a   right turn  out to sea  with with heavy snow being restricted to Southern New Jersey Eastern Long Island and Cape Cod  and Moderate snow  over   Northern NJ NYC  and  CT.
 However  the  12z  GFS   ensemble  mean   is of more aggressive in showing a bigger system for the Middle Atlantic coastal areas.  I did not accept this model is being valid.   However this was followed by the midday British model which did close off a Upper low  over  KY   and   WVA.  This causes the model to grab the surface low and pulling back towards the coast  the slows it down and deeps  it so you get a much more significant storm and heavy snow into the big cities of the I 95 corridor.
BRITISH MODEL    followed the  GFS  ensemble eman   with a    somewhat stronger   Low .
  And finally the afternoon European ensemble came out and it is even more bullish and aggressive with this whole system by developing an explosively along the North Carolina Virginia Coast and then tracking  it fairly close to the coast.  If the European ensemble mean is correct  this would provide significant if not heavy snow from northeastern Virginia up thru DCA  and  PHL  then  into  NJ  NYC  CT  Long Island    and  se  Mass. 
The fact that the  GFS  ensemble    the   British model and now the European   ensemble all show a stronger system …  That is closer to the coast    leaves the open to the possibility that the precipitation amounts may be increasing on some of the model runs as we go into the weekend ., Monday morning we could be looking at a much wetter system  then what it appears  to be today.


1830    EST  JAN 5  

There is a free the newsletter which you can get from  me…   To see a sample   of the  newsletter     CLICK    HERE.   The newsletter covers the next two weeks in Virginia and the neighboring regions and is issued twice a week…  Usually the Sunday afternoon or evenings and again on Thursday morning.  After the winter season of course the  VIRGINA   2 WEEK  FORECAST  Newsletter  continues so you complain your warm weather activity 2 and 3  weeks ahead.  If you wanna get on the mailing list…  Just drop me a line
 at     [email protected]   and   say     ”HEY   DT   put me on the mailing list.” 

I am running way behind schedule to date because of  2 hour orthodontist  appointment for my son.  Normallly  this  UPDATE  would be online by 430   OR  5:00 PM 

Later on this evening I will be issuing some snow maps for the arctic Low which is going to develop off the New England Coast  JAN 7-8.  The model data is pretty clear that there is going to be a  NORULND  trough which is a special  and somewhat rare weather feature.   The  Norlund trough  will   extend over Eastern NY  State  into  western  CT  and portions of Long Island  into the Low itself.   This   1st GUESS  snow map it is going to be a high risk forecast since getting these sorts of features    right  can be very difficult.  I would not at all be surprised if over the high terrain of southeastern New York Hudson Valley into southwest Connecticut  12″   or more of snow  fell… yet  50 miles  away   Nothing  falls.   

OK and lets move on to the bigger event for January 11.  I have been talking about this event since December 28 – 29 and yesterday when all the model data was showing the inland track of the Low…  and possibly going up the spine of the Appalachians  with a late  redevelopment   of the Low to the coast…   I tried to argue that the solution was not viable given the overall pattern.   Instead I took a lot of nasty comments  from the ignorant weenies  in  the gallery. 

Today I looked a helluva lot smarter to them that I did yesterday.    This really is NOT  rocket science but if you are so desperate and hung up about getting a snow storm in your backyard that you simply ignore the actual weather pattern and latch onto what ever model is giving you a big snow…  then you always going to be wrong and always going to be behind the eight ball. 

It’s meteorology  NOT Modelology…  And  yesterday far too many    people  who knew  better were practicing that. 

Remember   weather  patterns of drive weather features and the weather models  tried to simulate  actual weather patterns.   Sometimes   weather models…  either one or all of them ….can miss features which cause  Models  to   behave erratically   and we  see model flip flops and reversals. 

That being said the important lesson that we have learned from the DEC   26th big East coast storm  is that when ALL of the weather models at the same time / Model  cycle  change  course    and they ALL show the   same  thing…  it usually means something significant.   If you recall    on DEC 24  the weather models which had showed the big East coast storm for several days due the reversal and showed no storm at all.  However on Friday afternoon the weather models southerly change course and showed a significant snow up and down the East coast with a very strong area of Low pressure . 

No one was sure what to make of this dramatic turn of events   but when ALL  of the 18z  DEC  24   Models  and ALL   of the  0z DEC 25   weather Model came out and showed the trend continuing…  That dramatic shift should have been interpreted as a major change.  Instead what we saw was incremental changes on most of the TV stations and NWS  forecast  over  eastern  VA and the Lower  MD  eastern  shore. 

SUMMARY…. The   **threat**    for seeing significant snowfall –over 6″+– has increased over much of central and eastern NC and eastern half of VA.    There is also the increase in the risk of seeing significant snow into the big cities of I 95.    But there is still equally High risk that the Low will slide off the coast before the heavy snow reaches those big cities in the Northeast.    Once again far western NC   western  VA and western MD   could miss out on the significant snow.
WE start out by    reminding    folks  that the  Tuesday 12z  GFS  and Canadian  weather models showed  the inland track.   I argued vociferously against this solution because of the overall pattern.  Sure enough  the   early morning   (0z)  GFS and Canadian models shifted the Low’s track  to the south  by  300-400 Miles!  
This first image will help explain the overall situation and what has to happen for VA  NC  MD  and DE to see a major snowstorm on January 11. 
As you can see the there are two important features or pieces of energy in the jet stream which in the weather business we call SHORT WAVES.   One is located over Western Texas the other one over the Pacific Northwest.  Many of the weather models had been taking this system as it comes out of TX and squashing it  as it moves  towards  Georgia.   Last night the Canadian model was suggesting that this feature over Western TX is going to hold together as it comes into GA which will allow the second piece of energy to merge or Phase  into one big system.  This in turn would produce a significant coastal storm. 
 Got it?  

We can see how the Canadian model does this over these next two images.  At 120 and 132 hours  the Model  shows feature #1 holding together quite nicely and allowing the phasing to take place. 


At the surface this is what the early WED morning Canadian model looked like.  As you can see   the Model   has a major Low over the Gulf coast states which moves into the Carolinas and Virginia and  brings a  glancing blow to central and Eastern MD VA and Southern NJ. 


The 0z European model whch we can see here at  96  and  120 hrs  also has a very strong feature over Texas. ( LEFT  side  maps Jet stream  RIGHT  side  maps  surface) .       But at 120 HRS     feature   #1 is getting washed out or crushed as it moves into AL and GA.  Because the European model  is killing the first feature ….when the second piece of energy catches up to it   it becomes much harder  to develop a significant coastal storm.  


See?       The 0z  WED   GFS had a very suppressed system as it almost always does when you dealing with very cold arctic air over the eastern Conus so my opinion it’s not even worth talking about. 

The  6z   WED GFS was a little better and had the system stronger that was   closer to the coast and at significant snow over much of NC and   MD. 

 The WED 12z GFS was pretty close to the same as the  6Z GFS  with moderate snow over portions of NC into  central and Eastern VA   but very little  snow  North of Fredericksburg and Charlottesville. 

The important run was the Canadian model from this afternoon because there was widespread belief that is as impressive as the Canadian model was early Wednesday morning… the 12z  Canadian model would probably not show that sort of impressive set up.  However the Canadian model DID hold the stormy snowy pattern  and if anything increased it .    

 Here is the jet stream map from the  12z  WED   Canadian valid for Monday night January 9.    Then  model has   feature  #1  looking   very strong …quite vigorous over  ARK northern MS  and Western TN and because the model has    this  feature   so strong the second feature coming out of the central Rockies   can merge or PHASE.      This results in the  12z  wed afternoon Canadian model showing a major winter storm with a large area of heavy snow covering all VA   MD   into  WVA nd  eastern  KY    and  by   day 7… JAN 12 then heavy snow spreads into  NJ  PHL  NYC  Long Island and  CT. 


As promising as all this may be the we still have to be concerned that two things could go wrong with this major winter storm threat. 

 FIRST   the lead  Piece  of  energy   (short wave)   coming at a Texas has got to survive.  If it does not survue and it gets  SQUASHED     there will be no big snow  for   anyone! 

Second one has to be concerned that the system does not slide out to the south and east.  We can get a very nice Low but its not at all certain that   the Low  is  going  to make it   as far N as the Canadian model is  now showing.  

And we also have to be concerned that the   12z  European model continues to show system  #1 — the  lead piece of energy over  TX– getting squashed as it comes east into  GA. 


However if you look closely you will see that with each model cycle  of  the European model..  system #1  is still  be squashed .  BUT…. the model  is doing  this  later and later.  

The delay in crushing the the first system means  that    there is More energy   so that a Phase  CAN  take place.      Over the last few runs the European model has developed heavy widespread rains across all of the gulf coast states and significant snow in portions of Northern Arkansas Tennessee Northern Mississippi Northern Alabama and Georgia.  

We can see this slow a subtle shift in the European by taking a look at this image.  The top maps deferred to the early morning Wednesday European model run…  And the bottom maps   are the  Wednesday  afternoon European model run.     These map s may look the same but there are subtle differences and the precipitation shield is much stronger on the bottom maps….  the  12z  WED      European Model. 


EURO  ENSEMBLE   0Z   vs   12z 


 The 0z  European  model run had No snow over Raliegh or Richmond and only a little snow over  Norfolk.   But the   12z  Wed European…   has  a LOT more precip  over  central and  eastern  NC   and   eastern  half of  VA.   (about  3″  at  Richmond   and 6″  at   Raliegh into  Noroflk) .  While this is NOT  as much as  the Canadian it is a increase from the  0z   European Model run. 


Posted by wxrisk | GENERAL | Monday 3 January 2011 5:00 pm

1705   JAN 3    2011  …..  CLICK  ON IMAGES    FOR    FULL SIZE

 The winter   of 2009-10 which was supposed to be a fairly mild and easy going winter especially after the holidays… is turning out to be a real pain in the   ass.  There are an awful lot of energy forecasters  out there whose JAN 2011 forecasts are already in the crapper.  Moreover if you look at the La Nina  Winters that featured colder than normal Januarys over the central and eastern U.S.  almost all of them featured cold and stormy Februarys as well.

There are   two major  things  I want to   discuss.  The first event  is the potential for significant winter storm over Eastern New England January 7-8.

As I stated in the  last update this is not really a CLIPPER  LOW per se.     This Low  develops on the arctic front which is why it really should be called  an   “Arctic Low”.    The 0z   MONDAY  JAN 3 run of the  ECMWF was very bullish with the system by developing the Low way to the  south and west… off the NJ coast. 

This sort of   explosive development of the arctic Low near the New Jersey Coast would not only bring New England a major snowstorm but you also hammered NYC with over a foot of snow easily— as well as New Jersey and Philadelphia.   And as a system pulls away from the coast    the 0z   Jan 3 European model   “bombs   the Low out”   and develops strong N winds over 30 or 35 mph.     While 0z  European model solution is  possible strongly unlikely to verify the cause in order to get the Low to develop  that close to the   NJ coast   there has to be a  southern Low  coming uo from  VA.  The problem is… that is not  going to  be a southern Low.

The 6z GFS has a much more realistic solution by developing a powerful low pressure area off the southeast coast of New England.  We can see this solution here.

This  solution  is  supported   in some ways  by the 12z  Jan 3 run of the GFS.     However the 12z    run  shows an exceptionally strong and  intensifying Low pressure area that would be easily bring blizzard conditions to much of Eastern New England including Cape Code and Boston.   The  Model  bombs it out to  966 mb off the southeast coast of Massachusetts … then if that was  not extreme  enough…. the  GFS stalls  the Low    east of  Boston  for 24 hrs.

Not surprisingly the model produces a huge area of precipitation– all of it  snow  with  over  36 inches of  an all of Cape Code  and  12-24″  over   eastern  Mass  far eastern   CT  and  eastern Long  Island.  And as a result of   the 12z  GFS   has  NO significant  snow  in western CT or  NYC.

The 12z   Jan 3 European model has finally come to its senses and develops a   strong   surface Low  over    eastern  OH/ western  PA   the morning of JAN 8.   This Low  will bring moderate snow  to   Northern  WVA western MD PA   NJ NYC   NY.   The  the Low will     ” bomb out”   well off the SE Massachusetts and coastline at  974  mb on JAN 9.     Not surprisingly  the    12z   JAN 3  European model does not bring  2″+ of  liquid  to far eastern Massachusetts .


Of course as I have been saying for last couple of days  this is NOT and    ordinary  “CLIPPER LOW” .   This system is actually associated with the  PV — polar vortex– that is being forced out of Central Canada into the Great Lakes and New England.  Once the storm begins to bomb out    east of the  New England  coast the arctic air mass associated with the polar vortex will come pouring southward on strong north winds.  Many places in  VA MD   DE  will not see max temps   past 30 degrees on the  JAN  8  or 9   with n or NW winds of   20+ MPH.       This by the way is the weather channel’s    ten Day forecast issued   January 2 for  Richmond   VA.   This is just embarrassing.


This next event for start appearing on many of the ensemble data around December 28 – 29 and the cause of the overall pattern I  have   been somewhat optimistic or  excited about the potential for this event.   I have always held true to rule that the big  East coast  snowstorm events   you can see  coming   days and days out.  Of this was certainly the case with the January 1996 blizzard as well as the president’s day II snowstorm in 2003 and    the   Major   northeast US   snowstorms  in 2005 and 2006 as well as the major snowstoms  over the northeast which were so common last winter .

The key to this storm  THREAT  is going to be three particular features.    First    we are going  to have to get the large polar vortex over southeastern Canada to move out.    If   it  does NOT  then  this  system is not going to bring any    snow north of Philadelphia.    The other features has to do with two piece of energy in the jet stream which  on JAN 8-9  will be located over   eastern   TX and the Other over  ID and  southwest MT.   Some of the weather models are crushing work showing off the lead piece of energy over Eastern Texas but some of the models and  ensembles  are   merging  –or “phasing”  the  2  over  the Lower Plains and   Delta.

Here is the  0z   JAN 3 European model from last night and as you can see it as a major winter storm over the entire mid Atlantic states up into Southern New England.  The map bears striking similarities to January 1996 and the model produces over 1.25   to 1.75″  liquid  to   much of   NC except for far western portions … VA  and  MD again except for the far western portions …     the eastern  25% of PA…  all of NJ   NYC Long island  and much of Southern Eastern New England.

Here is the   12z JAN 3 GFS…  And it shows the two pieces of energy quite nicely in the jet stream which we  are going to have to watch and see how they interact and develop .   By day 7.5   the GFS has a major pieces energy moving into the Mississippi Valley and developing a significant coastal storm shortly afterwards.


 This Link  shows  the  12z  GFS   precipitation forecast  for the period of JAN 11-12.   The  dark  Blue  band   is 0.50 to 0.75″ which given the high  snows   ratios would be significant snowfall .

 BY  Day 9  the Model  has a decent Low– not nearly as strong as the European models but impressive nonetheless– and it shows a massive arctic High over  northwestern Canada Poised to come plunging southward.

  The 12z JAN 3 European models out and it is pretty close to what the earlier model was showing but the  Model develops the coastal Low a little further to the north and a little later.  As a result of this run of the European model does not have nearly as much heavy precipitation over Maryland North Carolina and Virginia although it still has significant about.  However it this point in time we’re just quibbling says it still nine days out and the important thing is that the model still has the system as does the Canadian and the   GFS.


 these maps  are  stunningly  and  severely cold.  This Map  shows the  JET stream map…    please note the  BLUE  Lines  coming   from the   top of the map– the  ARCTIC  circle.   These  Lines  actually reach from  SIBERIA  …  then  move across the  North Pole and plunge   south    bringing severe  cold   into  Northern TX   by JAN 12-13  and  as far eastern   eastern TN    WVA  and PA.

 Mid  40s  huh?  Great call  Weather  Channel…..


1130  AM   JAN 1

Happy new year anybody and let’s hope that 2011 as a darn sight better than 2010.  Lots to talk about so let’s get right to it.
First  lets deal with the  January 7 – 8   threat.     This event  is not going to be a Middle Atlantic winter storm but it will be a  very impressive New  England  snowstorm .  Anybody  who tells differently does know what the talking about.    How can I make  that call and what has changed?
The European model and some of the runs of the Canadian and GFS were focusing on more energy coming out of southwest  Conus. That is no longer the case because there is  not enough energy coming out of the southwest.  All the model data continues to show  that  the strong polar vortex will  dive out of Hudson’s bay Canada and move  through  the Great Lakes   then  into New England.  Earlier it looked like this movement would combined with the energy coming out of the southwest to form the Middle Atlantic coastal storm.
Now that being said it is still possible that there may be SOME  snow over northern and Central Virginia Maryland Delaware into Southeast Pennsylvania and Southern New Jersey.  This lighter snow may occur for two possible reasons.  First there MAY still be  some southern stream energy  that  provides some  moisture  and  snow JAN 6-7.   Second   the  Huge  intense upper level Low  in the Jet stream as   it swings  through  the   Northeast  COULD  bring snow showers to much of  VA   DE   and MD.
  Instead the main focus here is going to be this monstrously   cold and dangerous  PV — POLAR  VORTEX which is going to  be  THE major  weather story   JAN 6-11  over the eastern Conus.  The movement of the  PV from Hudson’s Bay  through the Great Lakes into New England is going to cause a surface Low to  develop over the Northeast then bomb out off the SE Coast of New England  JAN 7 .     This  sort of   Low in the weather business is referred to as a     ” CLIPPER LOW”      because typically    these  weak  fast moving  Lows and   are  associated with pieces of energy in the northern jet stream that comes out of Western Canada and  track   through the Midwest   and into the Northeast.  But in this particular case  this Low is directly associated with the PV being displaced so far to the south so it is not really fair to call this system a  Clipper Low is more like an  ARCTIC   LOW.
Beyond next weekend the pattern remains extremely impressive and threatening for another major East coast winter storm.  Back on December 28 I mentioned two possible dates :   January 7 -  and the other one was January 11 – 12.  The first event IS going to happen but   the storm won’t be  bug deal  for a Middle Atlantic  –   more like New England. The severe cold  will be.    The second   date / threat is giving more more indication of a major event.   Let see why.
The Arctic Low gets absorbed by the huge and displaced polar vortex over and far southeastern Canada.  This occurs  because  of the   Monster  Block  in the Jet stream over  Greenland and northeastern Canada.     Thus the  Low and PV  become   trapped over  for se Canada.  Meanwhile we have a strong ridge over Alaska and the Bering sea which is actually quite typical for moderate and strong La  Nina winters.
That ridge in the Bering sea is producing a persistent trough along the West coast of North America and one of the reasons why its turn so stormy and cold from British Columbia all away to San Diego.     From that position …   the typical  or   normal  winter La Nina pattern should produce a ridge over the southeastern states and the storm track should be moving from the southwest into the  eastern Great Lakes.
But that is   not what  is happening because of the block over Greenland and the huge polar vortex stock over southeastern Canada.
As a result the West  coast energy can only track in one direction which you can see the  here.  These  systems can only track  in a easterly direction  because of the overall pattern.  The Model  AND  the pattern clearly supports a significant system developing over a portion of the lower Midwest and into the the Northeast US sometime around January 12 – 13.
Here is the 0z  GFS  at  Day 10 and we can clearly see the Southern Energy moving into the central  and  lower Plains and developing significant precipitation and Low pressure.   BY 300 hrs  the  0z GFS is clearly hinting at some sort of storm    for the  NE US.
 The 0z European  at Day 9 and  Day 10 support this idea as they show significant wave of  Low pressure along the arctic boundary moving through Arkansas and tracking chords Tennessee and North Carolina.    
 Next we have the 0z   GFS  surface    ensemble maps…  And again I  have highlighted which maps are showing a significant winter storm developing  at    day 11  =   JAN 12 .  Of the 12 maps shown    11 of them show a significant  Low  and  4 of them  show a Major event  brewing.
 This Image shows the 500  MB or Jet stream Maps  from all 20  members of the   0z GFS  ensemble for day 11-12.  And again there are very strong signals  here for something significant happening around 11th or 12th of January.