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. 


  1. Comment by Wayles — January 22, 2011 @ 2:18 am

    Great stuff! Thanks DT.

  2. Comment by Johnny — January 22, 2011 @ 2:28 am

    Great job explaining things D.T!

  3. Comment by Nick McElroy — January 22, 2011 @ 2:28 am

    When you say it implies to NYC do u mean it could stay all snow or the part with heavy snow before the change?

  4. Comment by JD — January 23, 2011 @ 8:05 pm

    Any chance of that Greenland Block coming back??????

  5. Comment by ski — January 24, 2011 @ 4:00 am

    I read your Web site for the excellent explanations you provide for your forecasts, and I appreciate the effort you put into providing those explanations. I just wish you would do something to eliminate the enormous amount of typographical and grammatical errors you publish.

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