HAS THE WORM …TURNED?

Posted by wxrisk | GENERAL,WINTER 2011-12 | Tuesday 29 November 2011 9:00 pm

2045    HRS   EST   29  NOV   2011…   STARDATE   201111.29

I am doing it this evening update because several things have changed on some of the afternoon models which deserve comment.

A lot of the speculation in the weather committee both within the energy sector and those on the various whether forms that the winter is in trouble or delayed or not going to be significant has been based primarily on the perception that this winter was going to get off to a bang upstart… in a manner similar to what we saw last winter and in the winter of 2009-10.

Since that clearly is not going to happen…. a lot of the energy meteorologist and private sector weather information providers have been backpedaling on their winter forecast.  I am one of them …     my  DECEMBER  2011   forecast is probably going to be too cold east to the Rockies with respect to a temperatures….  especially in the area were a have the  -4° F  region.   My point however is that once the energy forecasts became known through the weather hobbyist community it caused a corresponding   increase in the dissipation and expectations   –  HYPE.  Now that we have all   had  to backpedal on that …we  are seeing the same affect  swing the  the other way.

For example even though most of the model data over the past 24 hours have a showed a pretty strong -EPO   West  coast ridge   ( +PNA)    and  downstream  trough  in the  jet  stream over the  Midwest  in the  6-10  day.   But the overwhelming amount of consensus forecasting from the various private weather servic’s  has been that it is not going to last.  In the 11-15  day the   +PNA is going to break down.

In other words  the -EPO will lose its intensity and the West Coast Ridge  will collapse and it will slide back out towards the dateline in the north Pacific .  This means of course no flow of cold air into the  central  and / or eastern Conus and it could even imply a return  to  -PNA   ( West coast trough)    which is the pattern we are  just now coming out of and which has dominated North America since Halloween.

The reason why these private forecast services have been suggesting that is because the model data was showing  that!  In other words   they  are not making this up….

For example here is the  0z   11/29  run of  the ECWMF    500 MB  for  day 9.  As you can see the entire West Coast ridge pattern has completely broken down.

 So then …the KEY ISSUES  are      1)   how  Long does this   cold pattern  last??     2)Does the    +PNA pattern   break down and do we  return to  a pattern like we have seen for much of November???

In my opinion the argument that we are going to see a return to a super warm  -PNA    November like pattern is  wrong because it misses how we ended up getting such a warm pattern.   It is  NOT  the   had   a -PNA pattern and +NAO over  north America. There was something at  play here.

The super warm November of 2011 was caused in my opinion by the development of a large  500 Low– a  POLAR  VORTEX — over Siberia which moves across the Bering sea into Alaska during the month.  At the same time  a Ridge in the North Pacific was trying to expand and push north towards the Aleutian islands and the south coast of Alaska.  These two forces cause the Pacific jet stream to  “COMPACT”  :     we could   be seen by noting the very strong wind speed velocities at 200  MB during the month of November over the north Pacific.  At times the speed   were  up to 200 knots.  This  extremely fast  Pac  jet not only ensure a persistent trough  over the West Coast but it also cut off the flow of any sort of cold air getting into central or Southern Canada.

All that being said it should be pointed out that the  GEFS–  the  GFS   ensemble– has been much more bullish with a cold  pattern for North America.    The Tuesday afternoon /12z    run of the  11/29    ECMWF  the European model change direction dramatically and ends up showing a vastly different pattern the one who showing this morning and one that is much closer to what the  GEFS  has been showing for the past few days.   Even more surprising is that the European ENSEMBLE    agrees with with the  Operational  European and the GFS  / GEFS  ensemble!

To show you how big the changes are let’s take a look of this first image.  There are four maps here….  Both maps on the left side are the Day 9  European  model … on the right side  are the   day 9  GFS  model.   the TOP are the 0z  runs  the Bottom maps  are the  12z    runs.   As you can see the European high showed a huge change  from 0z to 12z  runs.

Now that   this sort of  BIG Model  flio flop is  not always a good thing   because that sort a big change in model consistency especially with a good model like the European can be troubling.  On the other hand the fact that the European is turning towards the GEFS  ( GFS ensemble)   could be significant.

 Here is the   12z   11/29   GEFS at  Day 10.  I have e highlighted some important features here so that you can see why this map is significant.

 By   324   hr    the   GEFS is showing some changes. The   Big  west coast  Eidge   ( the +PNA) has broken down and is moving   (retrograding )  west towards the dateline.  But also note that the bright red area over the azores  at  240 hrs    is  STILL there at   324  hrs. 

 This image shows you the   day 10   euro  from  the 12z  run 11/30.   I have highlighted some features for you to take a look at.  Let me be clear– this is not in any way a   Major  or  a Severe arctic outbreak of cold air.  This is a  good cold   (seasonally cold )   early December looking map.   

But clearly the most important feature on the European is the development of a strong   north Atlantic  Ridge  in the north central Atlantic which appears to be pushing into Iceland and the southern tip of Greenland.    This is not technically a -NAO but by Day 10   it appears to be on its way of becoming one.     Again this is a major change in the European model and it does so because the model develops a strong piece of energy   — a shortwave– that bombs a  surface  Low  off the Gulf of Maine Coast DEC  7.     This Low moves up into   southeast  Canada which in turn causes  the     N  Atlantic ridge to develop and expand towards Iceland in Greenland.

The 12z  European ensemble generally supports the operational European to a large degree.    As you can see the model actually does support the north Atlantic Ridge Building   towards Iceland / Greenland which quite frankly surprised the hell out of me because I thought the operational European was on its own.    In addition the model has slowed down the movement of the  West coast ridge    sliding  back to the  west somewhat.

 

 To show you what this looks like at the surface  …here is the    large scale  day 10  European map with 850 mb  temps…
 and the   close up  view of  Just the  CONUS and    far southern Canada.    As you can see as cold and over the upper Midwest  and  the Great Lakes it’s pretty darn cold.

 

Here is the  12z   11/29   run of   the GEFS     500 MB  height  anomalies   for the 6-10 day and 11-15   day.  As you can see that very strong positive height anomaly along and just off the west coast of Canada in the 6-10 day .    IT  does   slide   WEST  in the 11-15 day.    This causes  the cold pattern  to relax somewhat but that does not mean we are going to see we turn to the super warm pattern  of   Nov 2011.

 

The GEFS does not show a strong north Atlantic  Ridge  expanding into Greenland and Iceland at  day 10 0 or day 13.  Instead the model has a very strong    “Azores  Ridge”.      And that  has  to be  watched because it is  very possible that the relaxation of the excessively stormy pattern in the northeast North Atlantic  will allow this  Azores Ridge  to expand towards  Iceland.

One last point….    The    current MJO impulse does not support a prolonged +PNA   and  true  classic  -NAO.  Most of the  MJO models  show the current impulse weakening as it moves into phase 4  and 5 and then collapsing or dining in the circle of death.  The change from what we saw on Monday and over the weekend…. when the various MJO    model  forecasts showed a strong   MJO impulse.  If in fact the trend is correct and the current MJO impulse collapses this  COULD  allow for a more rapid transition to a new and cold a pattern over North America.

 

                 

ABOUT DECEMBER …. Updated

Posted by wxrisk | GENERAL,WINTER 2011-12 | Saturday 26 November 2011 8:27 pm

2000  EST  26  NOV  2011….    STARDATE  201111.26

 
While thanksgiving is over  and MOST  the turkey  has been  eaten  so it’s time to get back to the weather biz.      (although I am a anticipating one more delicious Turkey left over lunch on Sunday afternoon)        First I’m extremely happy with the way this weekend forecast turned out.  Up and down the entire East Coast and in to the Ohio and Tennessee Valley this has been an extremely nice long thanksgiving weekend.     I do believe  one could make the case   that this   has  been  nicest thanksgiving weekend in the last 50 years or more!    Given a that I made this forecast  here on the  WEB  page and over on  FACEBOOK  for the  1st time back   on NOV   15-16…  I am  darn happy.

 However when I made that forecasts and in the subsequent updates to that I talked about how of as we came out of the holiday weekend  — NOV 27  –  it could be a difficult travel day for many areas over the eastern U.S.     The ixssue  is  a  slow moving   but important cold front which can be seen crossing the Midwest and the Delta  regions on the Saturday early evening radar.     Over the past several days the weather models have slowed the system down a  bit so that by the time and reaches this maximum intensity it will actually be Monday the 28th.
That being said … the  overall scenario really has not changed …its just a timing issue.     All the model data shows that energy coming into the base of the trough over the Delta region will cause an upper Low to form and separate itself from the main  trough over the Midwest.      When this happens is called a  CUTOFF  LOW.    But in this case… the   cutoff  Low develops a    negative tilt. …which is a sign of a very strong and rapidly developing system   over the TN  and Ohio valleys.

To show you what this looks like  here is the  12z    SATURDAY   GFS  Model  at  60  72  and 84  hrs   at the 500 MB  level.  I have  drawn in the trough axis or the tilt of the upper low and you can see it’s running from the northwest towards the southeast….  which is by definition a negative tilt. 


As you can see here the European models strongly agrees with the scenario as those the British model and the Canadian. 

 
At the surface a second area of   Low pressure is going to form over the Gulf coast states and be pulled northward then northwest under this deep   closed   cutoff  Low .  In addition the strong area of High pressure off the East Coast  — the feature giving  the eastern US   this  great weekend..  will still be a factor.   The  High off the coast will be  feeding  a  significant inflow of very moist air from the southwest Atlantic into the    the entire East Coast  region.    Over the Appalachian mountains    and into   the  elevated terrain  of  TN   and KY rainfall amounts will be quite impressive over the next three days.   Possibly as much as 6 inches a rain and some locations.

BUT then  things  get  tricky.  Note in those  GFS 500 MB  maps how many of those Black Lines develop around the upper Low.     At   72 hrs  the GFS  shows 4  closed contours around this very impressive   “monster”  upper Low.       That represents a great deal of very cold air in the middle and upper levels of the atmosphere  and as result the  GFS   Model shows that the low levels  COULD become cold enough over the high terrain for the rain to go over snow Monday night into Tuesday over Northern Alabama   portions of  Tennessee  into  Indiana   and much of Michigan.

 
For this reason I  have issued a  FIRST    GUESS map with regard to this potential for snow.  This is a very risky forecast and it is quite possible that the cold air never gets down to the surface in time to cause force the rain to change over snow.

 

Further to the east it  is pretty clear that there is  going to be a large band of heavy showers and thunderstorms developing over the coastal areas of GA  and SC     then  move into all of  North Carolina southern and   western   Virginia…  central Virginia   and all of  WV   and into MD and    western PA.    However as this band pushes to the north and northeast   it  will  weaken and fall apart once  it  reaches central and northeastern Pennsylvania and New Jersey.

Longer term we can see some major changes occurring in the overall pattern.  Of course it may not mean much for your particular location BUT….   if you want to take a look of the big picture there are some things to point out which are significant.

 

In this image  we can see the  Upper air    pattern  (500 mb)    from November 21 and compare it to the forecast to  the  day 10 European model valid for December 8.     We can see some major differences.    Note that the huge vortex and deep troug in the gulf Alaska and the Eastern Pacific Ocean on November 21 has been replaced by a very strong Ridge  that pushes up to the coast of Alaska!    Also the ridge over the central  CONUS is now being replaced by a fairly deep trough.  The strong Ridge  over Europe gets replaced by a deep trough.      So things are changing.

If we look at some other Teleconnection indices however we see some discrepancies.     If we look of the two week forecast in Trends from the GFS  ensemble   from  the ESRL    web site…  the    regular  GFS  and   the  PSD  version of the GFS both showed the NAO staying strongly positive for most of the time frame   ( perahps  beginning to move towards a Neutral  by day 13-14).   However they do NOT agree on the PNA.       The regular GFS model shows  moderately strong positive PNA  through  day  10-11….  whereas the  PSD version of the GFS shows an extremely strong negative PNA.

 

Clearly these two things are not the same.  The reason is that the PSD  definition of what constitutes a  -PNA  vs a   +PNA  is not the  same as   CPC/ NCEP definition.

 

We see the same sort of problem looking at the  Western Pacific   and EPO Teleconnection trends.  Both versions of the GFS are in pretty good agreement over the next 11 to 12 days with regard to the Western Pacific Teleconnection.    But they do not agree   over the  EPO  trends.  As you can see the PSD   version of the GFS shows wild swings back and forth  fromn positive to negative   then  negative back the positive  with regard to the EPO.


One of the ways and getting around this sort of discrepancy is to look of the European model and the European  ensembles.  I have placed the operational European run  at day 10 next to the  day 10 European ensemble.    The European  ensemble has a weaker ridge over the southeastern CONUS      so  temperatures are somewhat colder   east  of the Mississippi River.     But the important thing here is that both  the Operational   Europeran and  the European ensemble  show a very strong Ridge over the eastern Pacific pushing up towards the coast of Alaska .  To be sure this   is NOT   massive  or highly amplified  Ridge…  but it clearly shows  that   the PNA   is going to be in the positive phase   at  day 10.    

Clearly the   PSD   run of the GFS is    wrong. 

If we look at the   GFS   ENSEMBLE  temperatures at Day 7 we can see a lot of dark blue and some purple actually showing up over portions of the eastern U.S.–  mainly over the southern portions of the U.S.  while over the Northeast and the Great Lakes sees seasonal  early  DEC temperatures.   At Day 13…  we  see more of the same…

   

      Finally I suppose it’s  fair to say that there are TWO ways to look at the first 10 or 12 days of December 2011.  It is clearly not going to be as cold as what some of the private energy forecasters have been calling for.  On the other hand given the fact   that  +PNA is only of average intensity…    the AO  this still clearly positive  as is the NAO…  it is   almost a   miracle  that   Deep South looks  cold   while the   Great Lakes and the Northeast  looks  seasonal for   early    December.

 

 

 

====================

1900  EST  NOV  23  2011… STARDATE  20111.23

I am hearing report some various meteorologists both within the private commercial sector and in the energy sector which are either killing off the winter  of 2011-12   over the eastern half of the CONUS ….  Or they are significantly downplaying it.

I suppose to a lot of folks this sort of decision doesn’t make a lot of sense especially given that we’re just now entering the thanksgiving holiday.  From my point of view of I agree.  I think part of   the problem…  may be that the last two winters were so significant over so much of the country east of the Rockies and especially east the Mississippi River…  that many have become spoiled.    And because  there have been  2 significant winters in a row ..the anticipation and build up… the  excitement about the potential for this winter…  especially given some of the early forecast calls…  have all  contributed significantly to ” expectations” .      As a result …IF  it turns out that this winter is not going to be as impressive as the last two winters…  and you have been telling folks  and your clients that  thid winter  WILL be…     well then  you may have a problem.
We now KNOW   that November  2011  will end up  been pretty mild and there  has  been a real lack of cold air over any portion of North America.  Of course as I pointed out in a previous posting November 2010 was pretty mild as well…  So    this current  Mild NOV does necessarily mean anything.  But you have to understand if you are weather hobbyists WHY some of these other forecast services and private forecasters are already  downplaying  and/or backpedaling on the winter of 2011-12.

Essentially they  have been  following the overall pattern and they see the number of things wrong with it and they figure that by the time things change so that we are seeing  even   “seasonal cold”  temperatures  it may be  DEC 10  or 15.   Of course past the past December we still have January February and for most of     the CONUS   a good portion of March as well.  There is just too much data and indication out there   — the above and much above normal snowfall over the northern hemisphere and especially over Eurasia… the  super  warm  North Atlantic  ( the +AMO) … the weak    negative QBO and the   fact that the La Nina  has NOT strengthened steadily or dramatically over the past few weeks    (recall last Sept and OCT   the La Nina   dropped  like a  Rock)   to bail out on the Winter.

So at this point I have not given up in the winter and I certainly have not given up on December still being at least seasonally cold   or fairly close to being seasonally cold for a good portion of the central and eastern CONUS.     That being said some of us are just going to have to get used to the fact the last couple winters have been really good    with respect to  EARLY  season cold and snow for large portions of the central and eastern U.S.     The last 2 winters   really got cranking in December…  but there have been a lot of winters in the weather history of the country  in which December  was   either Mild  or   just OK  ( DEC 93 of the winter of 1993-94  comes to mind)   that did not get cracking until January and February.

If we take a look of the latest MJO plots 

  

 

    you will see that most of the Plots   show the  current MJO  swings around   into   Phase   3 and 4  and 5  over the next  2 weeks.    As you can see  here      in DEC    Phase 4 and 5    are    very Mild  temps  patterns  for  the  central and eastern  US.    This would lead one to believe that the mild pattern  over the central and   eastern US  is going to continue into the first 10 days of December.  

However that most of the medium range models do not agree with that scenario.  Keep in mind  tha the  current MJO  impulse   is pretty weak and it  is very possible   that it might  collapse  into the   ” circle of  Death”.

For example here is the first image which shows the DAY 10 European model hemispheric projection  from 0z   FRIDAY  NOV  23.  As you can see it does not show a very promising looking pattern at all.  All the cold air is bottled up across the arctic region and the overall pattern across the CONUS looks pretty darn benign.

 However the   12z NOV 23  European model both at the operational and the  ensemble level    looks  much more significant and promising.  At the operational level we can see  ( the Hemispheric  projection)  a major Ridge  developing in the eastern Pacific pushing  North  into  the Yukon and Eastern Alaska…  and a  rapidly in deepening major trough over Western Canada pushing into the Pacific Northwest and northern Rockies.  That certainly is a major change from the  0z   Operational  European  run!  The day 10  operational  European model    at day 10   shows a  3  WAVE  pattern –  3  distinct troughs over the hemisphere.  

 


Focusing more on the CONUS  at day 10 you can see the very impressive amount of cold air pouring south at a Western Canada driving across the continental divide  trying  to reach location such as Seattle  and Boise.

     At the   Ensemble Level  Day 10 day    the 12z  European shows a more improved pattern both at the hemispheric level and at the regional level.  At the hemispheric perspective we can see two distinct polar vortexes :  One is over northeastern Canada and the other  is over eastern Siberia.  This is a significant change from earlier in the month when we have the  PV  in Alaska and the Yukon.  In addition we no longer have a deep trough in the gulf Alaska slamming into Western Canada but now we have a “flat” or  Broad  Ridge.  Again NOT  good for  serious serious cold  air   getting into the CONUS   but  its not nearly  as awful when you compare it to what the pattern is look like over the past 10-14  days.

 


    This can be seen with better clarity on the regional shot  of   the day 10 European  ensemble   map.

It is quite possible that the deep trough over Western Canada will swing through an across the Rockies the Plains  the Midwest and into the East Coast during early in the middle portions of December.  It is also quite possible that the trough may stay over the western U.S.  and perhaps just reach portions of the Plains.    Certainly that is what the  MJO   amd its forecast   of  Phase  4-5  is indicating. 

 

DETAILED THANKSGIVING DAY FORECAST FOR THE CONUS

Posted by wxrisk | GENERAL,WINTER 2011-12 | Monday 21 November 2011 6:21 pm

1800  EST  MONDAY  NOV 21

WED NOV 23    -    this   probably  THE  biggest   travel day     of the year.      You may have heard from some others weather sources    (accu  blunder for  one)   that there might be a winter storm of some type over some portion the northeast on November 23 or the 24th .  Let  me assure you that is not going to happen.  All the model data today clearly moved away from that solution… which given the overall pattern    it   SHOULD  of been clear to   any  meteorologist   that   is was  very unlikely that there was  going to be an  East coast  Low to  begin with.

Basically you do not get a winter storm on the East Coast simple be cause a weather model produces a big     “L  “     along the East Coast.   Besides having  cold air    — which we do NOT  have — there have to be several other features going on in the atmosphere for a East Coast winter storm of some type.  And none of those things are occurring and they are not going to occur next week.

Instead we  will  see a Low pressure area form over Missouri Arkansas NOV 22… track of through the Ohio Valley… into WVA and  western or central PA  NOV 23.   With HIGH pressure moving off the East Coast…  winds will be   southerly  so temps  at all levels of the atmosphere will be much to warm for any sort of frozen precipitation .     We are looking at  Good rains   for  TN  IND KY late on the  22nd    into   PH  PA  on the  23rd  into  southern NY .   Even  locations such as Syracuse Binghamton as well as Buffalo will be too warm for snow .

JUST RAIN.  
There may be some snow over far Northern New York State and Northern New England….  that is to say central and northern NH and  VT  and  Maine on NOV 23 but for the big cities of the northeast  AND    the  Appalachian Mts… this will be all rain.

The Midwest should be clear and mild the entire day on the 23rd as will the Plains   the Delta  regions and the   Rockies.  Anyone traveling the California…   there will be some rain coming in two Northern California and the Pacific Northwest on the 23rd but central and Southern California as well as Vegas should all be completely dry with mild temperatures.

NOV 24  — very quiet and mild weather conditions across most of the  CONUS.  Only northern New England will see any sort of seasonally cold temperatures .     After chilly start in the morning hours over New England   the Middle Atlantic states  and  the  Midwest …. everybody  Easte  of   the Mississippi River will see mild pleasant   conditions for Thanksgiving Day … with TONS of sunshine!!!      New England  will see Max temperatures mostly in the   40s…..  50s  to   60 degrees over   MD  VA  WVA   NC   DE … and over  ALL of the Midwest .  

 NOV 25….  HIGH  pressure moves   off the coast  SO  winds  will become southwest   and temperatures will warm rapidly across all the Midwest and the entire East Coast.      It will be spectacular….  For late November.   Readings will push into the high  60s    or Low 70s  into  MD     VA NC   TN  KY  southern WVA   Low 70s over the  Deep South and    low 60s   for  all of the Midwest   EAST of the Mississippi river .  Only over the  Great Lakes  into  MN and the Dakotas will temperatures be in the   40s

NOV 26 … more of the same.    70 degrees  is LIKELY   for  all of  NC    VA   MD     southern  WVA    Columbus OH    Eastern Kentucky  and into  all the Carolinas and Georgia.    Temps will likely   reach   60+    degrees  ( maybe   65)     into Boston NYC     Albany   Buffalo  and Detroit.       But there is going to be a fairly strong cold front moving across the Plains into the western Great Lakes  ILL    eastern MO   and ARK and LA by midday on the 26th.  This front  will  cause significant showers and thunderstorms .     The showers and storms should reach   eastern  KY  OH    MI  by sunset on the 26th.

 NOV 27 ….   The Models  this Monday  have ALL turned to the idea of   the  Major trough   moving into  the Plains and  Midwest.      The    TROUGH    and the surface cold front will stall   because of   Huge Ridge off the   East coast. 

 

The  trough   will  develops a   TILT …  NW -  SE   ..which is called a NEGATIVE  TILT.     This Image   from the 12z   European Model  shows  the    Upper air   pattern….

 this Image  from the  12z  shows the SURFACE MAP  on the  evening  of    the 27th 

 

This is  DANGEROUS  sign   and a clue  for meteorologists  that  this   NOV 27   Low   is going to be a  BIG     DEAL.   The   strong   S   to N  winds     in the Jet stream   over the   East coast … combined with   warm Humid  air   coming in  from  FL and the sw Atlantic… combined with the Cold air  in   thr  Upper  Low  … driving a   strong  cold front   into the   East coast   will  allow for  heavy storms  and possibly    a  major    severe  wx  outbreak    late on the  27th for  TN  AL GA  SC    eastern   KY into  WVA….  then   into     NC  VA  MD  DE   PA  NJ   on the   28th.

 DT
  this will be updated    NOV 22….

NOT AS WARM AS IT HAS BEEN… NOT THE SAME THING AS COLD

Posted by wxrisk | GENERAL | Monday 21 November 2011 7:45 am

0730  EST    21 NOV  2011…     STARDATE  201111.21

I am sure someone like Bill Karins the morning meteorologist on MSNBC is a good guy and all but I am listening to him tell everybody that Wednesday, November 23 is going be a “really bad travel day in the northeast US ” because of all this heavy rain coming.    While it is going to rain a lot on Tuesday night and early Wednesday morning ….the data clearly shows that by a Wednesday 7 0700 EST most of the heavy rain will be north of Boston up across Northern New England Montreal and Maine.    I am not exactly sure what he is looking at but based on what I am seeing early this morning … that forecast is a lot of nonsense.   Here is the 700 MN RH field from the 0z GFS valid at 0700 EST Wed 11/23. As you can see the heavy rain is about to pull out of Boston and is falling mostly over interior portions of New Hampshire Vermont and Maine and Montreal.    This does not like a bad travel day to me up and down the I-95 corridor– perhaps some early morning delays but things should rapidly improve as skies clear out.  http://mag.ncep.noaa.gov/GemPakTier/MagGemPakImages/gfs/20111121/00/gfs_namer_060_700_rh_ht.gif

The other major issue has to do with the development of a potentially large close cut off  Low at the base of the trough on November 27 over the Midwest.    The 0z and 6z GFS are going absolutely bonkers with the system developing a four or five closed off contoured 500 MB cut off Low over the Tennessee Valley late on the 27th into the 28th.
http://meteocentre.com/models/gfs_amer_00/GZ_D5_PN_168_0000.gifhttp://meteocentre.com/models/gfs_amer_06/GZ_D5_PN_168_0000.gif

The European model which was showing this sort of development on Sunday has backed off of that idea.   The 0z Monday 11/21 run now the shows a deep trough moving rapidly through the East Coast and does not close off a deep 500 MB Low at the base of thre trough. http://meteocentre.com/models/ecmwf_amer_00/GZ_PN_168_0000.gif

The 0z Canadian also develops this sort of feature.    The development of this potentially significant deep closed cut off Low would be hard to overstate. Since the entire feature develops a negative tilt at 500 MB the downstream difluent flow along with the extremely warm temperatures … southerly winds bringing in copious moisture and the slow movement of the system …could set up a significant severe weather event for much of the Middle Atlantic states into NY and potentially into western New England lay on the 27th into the 28th.   Taken verbatim both the 0z and 6z GFS development of the deep closed 500 Low argues for SNOW to fall over the mtns of TN eastern KY southwest VA western NC and southern WVA .

The 0z GFS ensemble shows almost no support for this solution. A FEW of the individual members to show a closed 500 Low over the Tennessee Valley that moves through the Middle Atlantic states at day 7.     http://www.meteo.psu.edu/~gadomski/ENSHGT_0z/f168.html

The 6z GFS ENSEMBLE is much more impressive with 7 of 11 supporting the idea of a deep closed cutoff 500 Low over the TN or Ohio valleys.
http://www.meteo.psu.edu/~gadomski/ENSHGT_6z/f156.html

on the 6z GFS ensemble … 13 of the 20 member ensemble support the idea of deep closed cutofff Low … so I cannot rule out of the GFS completely. I am however worried that this is from a 6Z run which statistically as been proven to be more unreliable than the 0z run.
http://www.meteo.psu.edu/~gadomski/ENSHGTWIDE_6z/f156.gif

More impressive is the vastly improved NOGAPS model with its 4dvar… and its 20 ensemble .As you can see here not only does this deep close 500 low show up on the ensemble mean but 18 of the 20 members as well.
http://www.meteo.psu.edu/~gadomski/ENSNAVYHGTWIDE_0z/f168.gif

The Euro ensemble does NOT support this and closely matches the operational run.   By day  9-10  the model has a strong cold front sweeping through the Plains the Midwest and the Northeast. Low pressure is forming over Texarkana and it looks like is going be a significant snowstorm for the Midwest DEC 1-2.

  My view is that since the European or r European ensemble is not yet on board with the idea of deep closed 500 Low over the TN Valley on the 27th and 28th …. in fact it was moved away from that scenario — I cannot go with it  . I am not convinced that the European solution is correct but right now… given the overall synoptic pattern and the lack of high latitude blocking ….I remain skeptical of the extreme solution posed by the GFS the Canadian and the NOGAPS and their ensembles.  If later on today the European model turns back towards a solution well I will be banging that big closed Low idea… like a cheap whore.

longer Term … It appears once again that the usual sources are jumping up and down about some sort a major pattern change coming as we move into DEC….   And clearly the data does not support that sort of excitment or hype.  The data does show the pattern turning someoine colder of the central and eastern CONUS and ace and to the excessively torrential rains overt the Pacific Northwest.

Here we can see the deep 500 Low… the PV … That has been over the gulf Alaska and the Yukon… Retrograding towards the Bering sea …. Which in turn allows for some MODERATE 500 MB height rises to occur over the Pacific NW.   So the pattern   IS  turning a bit colder and more seasonal as we move into December.
http://raleighwx.americanwx.com/models/gfsensemble/00zENS11-15day500mbHeightAnomalyNA.gif

This shows up on the European ensemble as well.
http://raleighwx.americanwx.com/models/ecmwfens/00zecmwfens500mbHGHTNA240.gif

Again nothing overpowering but certainly colder than it has been ( which is NOT saying Much). However if we change perspective and we look at this from the northern hemisphere view      http://raleighwx.americanwx.com/models/ecmwfens/00zecmwfens500mbHGHTNH240.gif

We see that the polar vortex– 2 of them — are still on the WRONG side of the hemisphere for any sort of significant sustained colder outbreaks getting into any portion of the U.S. Or Southern Canada. The AO is very Positive as is the NAO.
http://www.esrl.noaa.gov/psd/forecasts/teleconn/images/compare.pn.png

the EPO is beginning to come back towards earth and near neutral conditions by day 15
http://www.esrl.noaa.gov/psd/forecasts/teleconn/images/compare.we.png

One last note in this concerns the current WEAK MJO… Don’t forget to look at this link which shows other MJO models besides the CPC GFS stuff.   Most of the GFS / CPC MJO plots show the current MJO impulse weakening moving into the circle of death somewhere in Phase 2.   The European Briitsh Japanese and Brazilian models do  NOT   shows weakening actually shows the current Impulse gaining mater intensity as it moves into phase 3 and 4 in early DEC.   Clearly such a development would have potentially significant impact on the idea of a cold December over the central and eastern U.S.

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml

POSSIBLE MIDWEST SNOWSTORM NOV 27 SEVERE WEATHER FOR EAST COAST

Posted by wxrisk | GENERAL,WINTER 2011-12 | Saturday 19 November 2011 7:15 pm

1900 EST   19 NOV  2011… STARDATE  201111.19

  A few days ago there was some “talk”   or speculation of a possible East coast Low and some winter weather Wednesday night into Thurday morning.  Of course as we all KNOW that Low is going to track up the Ohio Valley and the Appalachian mountains.   The Low for NOV 23 was NEVER a serious threat for the East coast because of the Deep trough over the northeast Pacific/ West coast AND the +NAO.   The combination of both of these features forces the SE Ridge of the US to stay strong and a INLAND track is the only possible solution.

The same sort of thing will the case NOV 26-27-28.  At Day 7 all the Models show MAJOR trough developing over the Plains and moving into the Midwest.  There will be one Low over the western Great Lakes on the 24th but that Low will “die” and a new Low forms over TN on 27th.  The trough as it bumps up against the HUGE East coast ridge goes
” NEGATIVE” — is tilted NW to SE. 

 

 

Up to this point the CMC the ECMWF and the GFS models all agree.

     The CMC and GFS somehow or another STILL manage to drive this negatively Tilted trough over the Midwest/ Ohio Valley to the East coast.  This solution is ABSURD and is meteorologically unsound given the overall pattern in North America.   The best I can figure it the CMC and GFS solutions only make sense if Lord Voldermot uses his magic powers.

These maps show the detailed 12z saturday NOV 19 run of the ECMWF for this event.   IF … IF the models are correct inb depicting the deep trough with a Negative tilt the severe weather threat for the East coast late on the 27th into the 28th could be “SIGNIFICANT”.

 

 

 

 

 

LONGER TERM… the day 10 euro ensemble shows 2 Polar Vortexes but both of them are NOT in good position for getting cold air into the CONUS.  If this map is correct the NAO is positive and AO is VERY positive into early DEC.  On the other hand we no longer have strong southeast US Ridge and the intense PV that has been over the Alaska and the Yukon is gone. That PV has moved into Bering Sea.  IF it were to keep moving towards the Aleutian Islands that could be a significant development towards altering the pattern.

Well at least Thanskgiving weekend over East coast looks Mild/ nice

Posted by wxrisk | GENERAL | Wednesday 16 November 2011 10:38 am

  16  NOVEMBER   1000  HRS  EST

From what I can see there is absolutely no reason at all to chaage to   current  attern  or even begin to speculate    WHEN things might   change. I know for the   ENERGY  markets and especially Nat gas  … those   who were  counting on a  cold  DEC  and a cold  DJF  are  already crying in their  beer ( for some reason)  and  some of  energy vendors  are   not looking very good right now…
 The first  vort max and   short wave  dropping southeast down the Br  Columbia coast  will develop into   the 2nd  BIG event of the   COLD  season OCT 1 – MARCH 30   for the nation.   The rains  over the Pacific NW over the next 7 days will be  impressive   and the  mtn snwos  evemn more so.

http://mag.ncep.noaa.gov/GemPakTier/MagGemPakImages/gfs/20111116/00/gfs_namer_168_precip_ptot.gif

 The  2nd short  wave coming into southern CALIF is  going to being BEST  rains   in the last 6 months   to the   DROUGHT   ridden areas of  TX and OK NOV 22-23 .
Longer term…  

 If we start out by taking a look at the day 9  European and GFS hemispheric maps we can see that the intense large PV  (polar vortex) that is situated over the Yukon and Alaska is not  being forecasted to move in any way …shape …or form from when   compared to the  model data showed   a few days ago.  Not only does this feature dominate the entire hemisphere a pattern but also the moderate negative anomaly over the day the straits approaching the Greenland ensures that the NAO  stays strongly positive for the next seven days at least.


The one thing that all the data does agree on is that the  EPO  stays  strongly positive  and given the humongous  PV in the Alaska -  Yukon region that obviously makes sense and should not be in any dispute.

http://www.esrl.noaa.gov/psd/forecasts/teleconn/images/compare.we.png

http://www.esrl.noaa.gov/psd/forecasts/teleconn/images/compare.pn.png
The  0z and 6z GFS  operational and the  ensemble are trying to bring the NAO and the AO  down to   near neutral levels by  11-15  day…  But for the life of me I cannot figure out why or how this actually occurs given the fact that the enormous and intense  PV    apparently is not moving from the gulf Alaska anytime soon.

 

 
Indeed if we take a look at the  0z  GFS   ensemble  and the  GFS  ensemble mean  at  240   hrs  we see the humongous   PV  sitting their dominating the entire pattern over Alaska and the Yukon.  

For those of you that have the European  ensembles   that Model’s ensembles  shows nothing that is substantially   different from what the   0z CMC  ensemble… the 0z GFS  ensemble or 0z  NOGAPS   ensembles  are all showing at  day 10  and at day 15.

The 0z  CMC    ensemble is  VERY  warm   over  all of the eastern half of the  CONUS    in the 6-10 day and the 11-15  day… at both the the  mean and each  individual   member

 

 as is the 0Z  GFS  ensemble.. 

All this being said I remain   unconvinced  that this  massive PV  is going to  stay  in its current position through say   DEC 15  or the rest of this winter.   It would NOT   take  a major  displacement   of the  PV   in  the  Yukon/Alaska to cause  a  significant impact on the pattern.    For example IF  the  PV were to say  slide  west   towards the  Aleutiains Island ….  then the  entire   pattern over   western N America would  change  and cold air would move into the  eastern Conus.   OR… if  for  example the   the PV were to slide  a few hundred miles to the east   into   central Canada  … that too  would have a profound impact on the current mild/ super mild pattern.

 

PV IN YUKON…. BAD PV!! BAD PV!!!!

Posted by wxrisk | GENERAL | Monday 14 November 2011 8:04 am

0800 14 NOV  2011

If it wasn’t clear last week in the weather models… it certainly is clear now:     there is  little chance of a turn towards a significantly colder  pattern over   any portion of the CONUS before December 1.  Again that in itself is not that unusual   per se.  But obviously as we move towards Thanksgiving and  the last   days of VOV  there will   be a big emphasis on whether or not we are going to see a significant large scale pattern change.  Last December that  is exactly what happened…  but  back in 2007-8   the   pacific jet   never let  up  and all of the DEC    cold in the    eastern  CONUS forecasts busted horribly.

In  looking at the “overall”   pattern I do see some changes of current  pattern. But with respect to affecting sensible weather conditions  in the  Conus….  there  is  not much to get excited about if you like cold weather.  It  is important that as a meteorologist we communicate in a clear and effective manner.  So while I can talk about changes occurring in the overall pattern at the high latitudes which over the long term could be more positive towards   getting a colder  pattern… the fact  is that  for most people this will sound like a bunch of esoteric   gobbledygook  because  their forecast shows  more  mild  temps. From the  average person point of  view   there  appears to be  no significant change in the overall pattern.

If we compare the current hemispheric  500 MB  map   as of 0z NOV 14   to the one from  NOV  7 we do indeed see significant changes.   The  PV has split which is what most of the models were  e forecasting and we now have one of the PV centers moving into far northwest portions of North America    (the  north  slop of    eastern Alaska/ Yukon).   The   other  PV has  retrograted and is now moving towards the north side of central Siberia on the arctic circle.   And we also seeing the widespread introduction of arctic air across all of Central  and Northern Canada which is something we did not see last week  or the  week before.  This is leading to increase in snow cover across Canada as well.  

 Another key aspect to the overall pattern is the powerful European or Scandinavian  Ridge.  Last week most of the model data show this Ridge  retrograting  into Iceland   or Greenland  but clearly that is not happening on any the model data over the weekend or this morning and that’s one of the reasons why the pattern change at the high latitudes is not working its way down to the mid latitudes.

Part of the problem is that the new polar vortex over Northwest North America splits into two sections. The  Eastern   portions  slides to Eastern Canada by the end of the week and moving towards Baffin island and the Davis straits by Day 7.  This movement initially causes a  moderate   trough to develop over the eastern CONUS   but once this feature moves into Eastern Canada were labrador in actually  cuases the NAO  to  flip  back to Neutral or  Positive and it also kills any chance of the Scandinavian   ridge   retrograting to Iceland.

This is reflected in the the  Teleconnections  Indicies…   http://raleighwx.americanwx.com/models/00zlinegraphs.html

However the western portion  of the  North  American  PV…. continues to move from the north slope of Alaska southeast into the gulf Alaska and along the Alaskan panhandle  by  day 3.  This feature slides down towards Vancouver Island and the Pacific Northwest    by day 7.     It  is a very intense vortex and if this was the middle of December  there is no doubt that this feature bring a major snowstorm to locations such as Vancouver and Seattle.  It still might give an how  impressive this feature is.   A piece of this energy  breaks off and develops  a  significant surface Low  that tracks of the western high plains this weekend with the arctic air pressing south across sea was Canada border into Montana and the Dakotas.  This will probably be the first serious winter storm for the Upper Plains of the season  — there was a moderate one last week .

By day 10  the  operational European and the European  ensemble show a dual center pattern with one PV  over central Siberia and the other one located over northwest Canada –perhaps in the Yukon. The PV  over   the  Yukon is clearly was stronger on most of the model data with  its  value     below 500 DM .   The Teleconnections from this intense vortex over far Northwest North America of course supports a strong southeast U.S. to ridge so all of the Model  data here  apears to be  very consistent and  meteorologically sound. 

In addition if you take a look at the  500 MB   height lines over the north Pacific you will see that the extremely strong central north Pacific    positive   height  anomaly  — the   Ridge   at 588dm– is located surprisingly close to the   498  dm   very strong and negative  height anomaly over the Yukon.  This of course is causing the Pacific jet to become squeezed causing ncreased  velocities to a extremely powerful  180 knots on the 0z GFS   at 192 hrs.    And  having the jet streak slam into    the  West coast  / br Columbia   ensures the mean trough stays on the West coast and  the  the cold air   building Canada  cannot possiblly   drop south of the   US Canada  Border .

Clearly the impediment in terms of getting the pattern to turn significantly colder is the extremely intense polar vortex over the Yukon.   This  fat  pig   has  got  to MOVE  or slide    southeast into   north central  Canada.  As long as that feature  is in  that part of the western hemisphere the pattern is absolutely no chance of changing.  This position for a  PV  has   long been know  as the Kiss of  death if one is forecasting any sort of sustained colder outbreak were pattern developing over the eastern half of North America.  Of course there have been plenty of winters where the vortex up there in northwest Canada in November has moved  to the southeast  which ends up altering the entire pattern.  But as long as that feature  is  there and the 180  knot    long jet streak ….     the central and eastern  CONUS stays Mild.

 

 

WHERE IS WINTER ? ARE WE ALL DOOMED ???

Posted by wxrisk | GENERAL,WINTER 2011-12 | Saturday 12 November 2011 12:48 pm

1200 NOV  12   2011

While it may be popular for some to argue that reality is based upon perception—  and that certainly is true in politics and public opinion polls— is not true in the world of science.  At least not in this sense.

The last two winters have been pretty impressive over much of the central and eastern U.S.    And given the number  of winter  forecasts which believe that this winter will be the same    kind of winter  as what we experience in 2009-10 and  2010-11…  there is  strong tendency  for some to forget  HOW   we got to those winters and what the Novembers    were  like.

Now with regard to  November of 2009…  wll that was just a nasty cold Autumn and  there arw no two ways to get around.    However most of the time   most people  make this  specious  connection  about  d October and November weather  patterns  and   Winter.   This is  especially true for cold and stormy Octobers and Novembers .    Often times even though the pattern appears to be promising for winter weather lovers based upon those two months…  there are many many cases where the pattern breaks down as we move into winter or the middle of the winter .

In other words it becomes very difficult– and it is  NOT  typical –for a cold & stormy pattern to last from say  November   to March.     This applies to whether you are dealing with the West Coast  the Plains the  Midwest or the East Coast.   When you do get a   prolonged  cold  stormy  pattern that lasts for that   ALL  of the Winter …or most of it…  well  THAT   is  what defines a “Historic Winter”.

For example last winter   the cold and stormy pattern broke down  in  February  of 2011 … so I would NOT  call the winter of 2010-11   “a historic winter”.        However I would call the winter of 2009-10   a historic winter.  The same definition also applies and defines WHY we remember the great winter’s of 1976-77   1977-78 and   1978-79  as well as   the  winter of  say 1960-61   1962-63   and 1993-94.    Ya  follow?   

That   is why  events such as  strong La  Nina   and or  El NIno  events are so important.  These  event  can and do provide enough energy into the atmosphere to keep the pattern locked into place.

But before LAST winter    kicked in ….November  2010   was exceptionally mild for much of the central and eastern U.S. without a whole lot of significant cold air outbreaks or storminess  on the East Coast.     The pattern flipped after Thanksgiving 2010    so that  by the  time you reach the first week of December there was a massive trough over the eastern U.S.   (recall tht last winter  saw a    high end Moderate  La Nina  event).

Since some   of you have forgotten what November of 2010 was like REALLY  like… I   think it is time for a little bit of hard reality and actual maps.    What is striking in that when we look at  November  2010  is how identical it is to the  the  CURRENT  NOV  2011  pattern over North America.

This first image shows us the 500 MB pattern   from NOV  9   through the  NOV 28 2010.  Again the apparent similarity between those maps on what we are seeing right now is striking and it should be somewhat reassuring for those individuals   who for what ever stupid reason they can come up … are already modifying  or cancelling  their expectations regarding the winter of  2011-12.

 

 

This  first image  has 5 maps in it.  The first map is from  9 NOV 2010…  And you can clearly see the deep trough over the West Coast  and a fairly strong ridge over the Midwest. The NAO is  strongly positive.   The  SECOND map   is  NOV 15….  The trough has moved into the Plains  but there still are Ridge over the East Coast … and it looks like some sort of ridge is trying to form on the West Coast.    The  3rd map  is 18 NOV 2010….  And we see a new deep trough developing over Western Canada and the Pacific Northwest and a   very +NAO!!    (Look familar?)   The 4th Map is   22 NOV  2010…  Which again the shows a new massive trough over the western conus   (really the entire west  coast of North America ) and a very strong Ridge  over the southeast U.S.  and a    slightly  negative NAO.   The fifth  map  is  from 28 NOV  2010…  Again shows a another deep persistent trough over the West Coast…  a strong Ridge  over the Midwest  and a  very +NAO.

Now lets compare those maps    to the second image….  which is the current  500 MB  map  from the last 10 days. 

The first one is dated  6 NOV 2011…  And of course we can see a massive trough over the West Coast and very strong ridge  over the eastern  CONUS… and    +NAO .   The next map is from  10 NOV 2011 and we can see a moderate sized trough moving into the Midwest…  with are near neutral NAO. The  3rd  map  is  from  12 NOV 2001… TODAY.  And what do we see ?  A  new persistent wrath over the West Coast….  and   a trough   leaving the   Northeast US and -NAO .     The   4th Map is  the   0z   European model from NOV 12   VALID  for  NOV 19…  Which shows a another deep persistent wrath over the West Coast   a  -NAO   and     shallow trough  over Eastern Canada and a   ridge  over the   Lower Plain and Deep South.

As you can see the pattern is strikingly similar to what we saw last year in NOVEMBER  2010.  It’s very rare in the weather basis to see 2  different Novembers that similar in overall pattern  back to back like this.

The final map is from 6 DEC  2010….  which shows a massive trough over the East Coast    a steady and large   -NAO and the ridge  over the west coast of Canada !!!   This should convince you that the pattern can evolve quite quickly …   and that the mild November we are currently experiencing for most the country   has no direct connection to all   as to what  is or is  NOT was going to happen in the heart of the winter  of  2011-12.

 

 

That being said…  it is also true that just because  NOV  2010 evolved   into of decent winter pattern for the heart of the winter od 2010-11 …  that it does not necessarily mean that THIS  November   of 2011 will also evolve the  same way.

The point here is not the panic at all and that give the pattern some time.   The big thing about this current pattern for the next 20 days is that it’s going to allow for significant snow cover and colder buildup throughout all of Canada.

DT

-PNA FROM HELL

Posted by wxrisk | GENERAL | Thursday 10 November 2011 8:32 am

1000  EDT   NOVEMBER   10

 Why is it that whenever I start   some sort  of  new venture ….all sorts of weird stuff seems to happen …both culturally and with me personally? …. Just one of those things I guess.

I will start out this morning by taking a look at some of the MJO forecast models and see how or what they are forecasting in the current MJO pulse over the next 2 weeks and what… if anything …they that can tell us about the evolving pattern. The Current MJO is of moderate intensity and located in phase 6.    This corresponds to the map   below where we can can see several important features.     There is a large area of strong positive height anomalies over Scandinavia and over the north slope of Siberia… And a strong negative high anomaly over the gulf Alaska.

http://raleighwx.americanwx.com/MJO/NovemberPhase6500mb.gif

In the general sense this appears to be a fairly close match to what most of the medium range models of forecasting over the next several days with the strong negative anomaly developing in the gulf Alaska as a series of strong Lows crash into Western Canada the Alaskan panhandle and eventually down by Vancouver and Seattle day 8-9-10.

In fact the operational European and the GFS Models do show a pretry potent system traveling down the Alaskan panhandle and slamming into Vancouver and Seattle November 19 – 20.    It does so because all the models are developing or expanding a Ridge over the Bering sea into Western Alaska.    Right now the model data shows 850 MB   temperatures clearly cold enough to support snow even in downtown Seattle and maybe even Portland…. which in mid November is pretty darn usual. The development of this Ridge at 500 MB allows for the first large cold arctic High of the season in Northwest Canada .

So whats happens with the current MJO impulse?

The first link here represents the NCEP GFS Ensemble mean which is forecasting the current impulse to reach phase 1 close to region 2 by November 24
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ncpe.shtml

The operational European MJO  model shows the impulse collapsing by the time they reached the thanksgiving weekend…
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ecmf.shtml

And this trend is supported by the European MJO ensemble mean and spaghetti plots
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ecmm.shtml

Therefore if we assume that the current MJO impulse will make it to at least PHASE 1 and POSSiBLE Phase 2….  We end up with this sort of pattern.     In PHASE 8 we can clearly see strong positive height anomalies at 500 MB increasing southeastern Canada…  and over Northwest Russia into Scandinavia. In addition we can also see strong negative height anomalies over the Siberian side of the arctic circle— which is currently were the PV is
http://raleighwx.americanwx.com/MJO/NovemberPhase8500mb.gif

By phase 1 however we see a strong positive height anomalies developing over southeastern Canada into Greenland and extending into northwest Scandinavia. This would count as a -NAO.    The very strong negative anomaly just to the west of the  UK   ould also be significant as would the intense Neagtive  anomaly over eastern Siberia.  http://raleighwx.americanwx.com/MJO/NovemberPhase1500mb.gif

 The PNA and NAO plots from ERSL show a moderately negative –NAO but it extremely strong a persistent West Coast trough / -PNA.   http://www.esrl.noaa.gov/psd/forecasts/teleconn/images/compare.pn.png

Even though the WPO changes phase sometime  around the Middle of   the month the EPO does not.   It moves into a persistently strong positive phase which of course means more strong negative anomalies over Alaska and the Gulf Alaska and above Normal Heights over southeastern Canada.    http://www.esrl.noaa.gov/psd/forecasts/teleconn/images/compare.we.png

This sort of solution matches all of the model data in the 11 to 15 day from the GFS and European ENSEMBLES .    What we are left with then is pretty neat tidy package of strong model agreement that matches the MJO November pattern for Phase 8 1 and 2.

While the strong ridge over the eastern half of North America and especially over the CONUS is going to be very slow to move out with a +EPO and a strong – PNA …    this pattern will allow for the significant buildup of arctic cold and rapidly increasing deep snow cover over the next two weeks for most of Canada.   If you are bored looking at thisn pattern east of the Rockies you might want a look at the increasingly cold temperatures and deepening cold air mass across all of Canada rght up to the U.S. Border.

One last point is to focus on the connection between the strong Ridge over the dateline into the Bering sea and the strong Negative anomaly over the British Columbia region.    I am sure it’s obvious to many but I thought I would emphasize the point that until the Ridge in the north Pacific over the dateline / Bering sea shifts or e altars position ….the -PNA is not going anywhere.   On the other hand if you are in Seattle… over Portland… Boise   Spoakne    Redding  Calif  into the N Rockies your winter is going to start early

PATTERN CHANGE BY THE NUMBERS — #2

Posted by wxrisk | GENERAL | Wednesday 9 November 2011 9:08 am

0800 EDT   9  NOVEMBER

First let me start out with a couple of announcements.  There is going to be a new subcategory  on  the WXRISK.COM   page.. called  HARDCORE

This subcategory will be dealing with the serious meteorological  analysis.  I hope to update this subcategory/ page   EVERY DAY  around 0700  EDT  or so.   It is going to be primarily aimed at energy meteorologists   Grain Meteorologists   TV Meteorologists  and  all those who have a need or dseire to read    serious hardcore meterology.   It will be free  for all.   The subcategory HARDCORE    will NOT  be for  the layman or average  person  and I  hope I will make that  make that quite clear.      For  average folks   that are NOT     Hardcore   weather   nuts or  professional   Meteorologists …     I will be using   WINTER  2011-12  subcategory/ page. 

Increasingly there are more signs that a significant pattern change is coming for North America.  And that even though the next 7 to 10 days over most of eastern  CONUS — and  eastern Canada  for that matter — are going to see some pretty impressive warm temperatures for the middle of November— things are starting to move and the pattern is beginning to shift. 

In the last discussion  -NOV 5– I pointed out the several key players hemispherically  which have to change with regard to the current pattern…  in order for some sort of reasonably winter like hemisphere pattern to develop. 
IMAGE # 1  we see TWO  Maps ….   the Map on the LEFT  side  is the CURRENT  hemispheric  pattern as of November 8.  This is from the 12z initial European model  (ECMWF)    ENSEMBLE  and again of highlighted some important key features.

As I pointed out back on Saturday we still only have one large intense Polar Vortex which is situated over the northeast the slopes of Siberia.  There is no PV  anywhere in the western hemisphere…  which is  one of the primary reasons why the pattern has been so Mild.  With the polar  Vortex  on the other side of the arctic circle there  is no large pool of cold air in the western hemisphere to draw on.  We can see this on the map on the right side….  The white line shows the boundary of the arctic air and as you can see it’s extremely far to the north a specially for early and middle of November.    So even if there  was want to get a large cold High to come south it would consist of mile Pacifc  air.     In addition we can see the strong ridge over the eastern third or eastern half of the  CONUS  and the Scandinavian rage extending from the Ukraine  into central and northern Norway and Sweden.

In IMAGE #2 …     there are  3 maps…. all   based on the 12z   ECMWF of 12z  NOV 8… and  all 3  are valid for NOV 15.  The first map again is a large scale hemispheric  view.  First we can see that the model is showing that the PV   is SPLITTING  into two pieces. 

 SECOND  the RIDGE over Scandinavia has now moved into the UK and is building towards Iceland.  This movement counts as a eastern based  – NAO feature. 

THIRD… the   strong ridge over the eastern half of the country has been pushed more towards the southeast and  Northeast  US coasts. 

  FOURTH… We can clearly see a massive trough developing over western and Central Canada….  and the big ridge  over the north Pacific  is sliding WEST  towards the international dateline.  This is allowing for the mean trough which has been over the West Coast to slide into the Rockies.

 The   2nd  map  in IMAGE  2…  Shows the large scale cold air pouring across the Arctic circle into western and North Central Canada for the first time this season.  The third map is just a more localized view of this…  with the arctic cold finally poaching the was Canada border for the first time this season. Also  note how  very warm it is  the Southeast  and Northeast  US.

IMAGE  #3  is the day 10 European map…  Valid for November 18.   Again we have three maps in image number 3 to look at.

The first image shows the hemispheric projection of the day 10 European.  We can clearly see two polar vortexes have  formed….  with the first or original   PV   now located over Central Russia near the Ural Mts.  This is important because if you recall the original position was over  north  side of eastern Siberia.  This movement  of PV #1  to the   central Russia   is  allowing to  Pac Jet to relax—   meaning that the Pacific jet is more likely to buckle or change shape.     And note that the powerful southeast U.S. ridge is now mostly out into the Western Atlantic Ocean.

The second map  in  image #3   shows the arctic air now moving into an across the U.S. Canada border…  And that the Arctic air is rapidly building up too impressive levels over all of western and North Central Canada!  Again why is important?–  IF Canada does not have any colder air in it…   it neither will the U.S.

The  Third image   is  again the   US Map …  of the  day 10 European model.  We can see the cold air finally moving into Northern Washington State hide a whole Montana North Dakota and Minnesota.

IMAGE  #4   is the chart of the 12z MODEL showing  the   NAO    and EPO   patterns. 

 There are four charts:   the  top   left  one shows the overall NAO.     And you can see that most of the models show this feature becoming consistently but moderately negative over the next 10 to 14 days.  The image on the top right  shows the west based  or GREENLAND  NAO.   Note here that the graphs  are all very close to Neutral…  which is telling us that the Scandinavia block has not reached as far west as Greenland.

The bottom  LEFT  map is the  east based  -NAO   and here we see  a strong   Negative signal which tells us that the Scandinavian ridge   does move    west  over the next 2 weeks.    The Bottom  RIGHT  map   shows the  EPO  phase which finally moves into the positive phase.

LASTLY  image #5  shows the  PNA   trends and all the model data continues to show this feature to be running strongly negative for the next two weeks. 

 SUMMARY:  the pattern is clearly going to start changing over the next 10 days.  But the key here is to recognize that it’s starting to change.    While all this is going on in the northern hemisphere at the high latitudes most of the next 10 days over the central and eastern U.S. will be mild.     For most people today will be seeing the weather pattern and their conditions every day…  and be wondering  “ where is  winter?”….   ” where is the cold air?”…

Assuming that the European   ENSEMBLE means  are correct….  true arctic air  will finally reach western and central Canada   by the 15th…  BUT  not the leading edge of the cold air will Just be  reaching the U.S. Canada border  by NOV 18 .  Assuming all this is correct seasonally cold air will NOT  reached the East Coast before November  20-22.

In addition even though the cold air buildup in western and central and Northern Canada will be impressive over the next 14 days… as  long  as the  PNA   remain   negative…   ( as long as the trough  remains over the  West coast or western   third of the US)     we are talking about a seasonally cold pattern in the U.S.    With a  -PNA there will be no mechanism for the arctic air building up and Western Central Canada to come south.

Now eventually  once the  -PNA   turns neutral and   then positive…  All that cold air building up in central northern and Western Canada will be able to come south.  And that could make for some mighty impressive cold air masses come  DEC  2011…. let me tell you. 

All in all if you like cold weather…  Things are trending your way.  Just remember…  We have a long way to go before we get out of this     super Mild  pattern.

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