FEB 22 PA EVENT… 2 Midwest Snowstorms LIKELY next 7 days

Posted by wxrisk | GENERAL | Sunday 20 February 2011 6:32 pm

1410  PM EST  FEB 20

We have a interesting situation developing with regard to the potential for some winter weather over portions of Pennsylvania and New Jersey and rumors… totally unfounded and irrational rumors …. that there some sort of significant snow coming for Northern Virginia and Maryland.
At first I thought this sort of wretched winter weather forecasting was coming from the usual sources— Herny M of accu weather but it has brought to my attention that for some incomprehensible reason that THE WEATHER CHANNEL also talking about some sort of accumulating snow over far Northern Virginia and Maryland including the DC and Baltimore metro areas.
That portion of the forecast… is crap. The real problem is that temperatures are way too warm for any sort of winter precipitation for any portion of the northwest VA as well as DCA / Baltimore metro areas or even as far north has the Pennsylvania Maryland border. Those areas are to warm at the surface …they are too warm in the Middle levels of atmosphere and they are two warm in the the upper levels of the atmosphere.

As you will see from the maps/ images below the potential does exist for decent accumulating snow over much of central OH into the northern half of VA western third of MD and over southern half of PA central NJ into NYC.

Complicating this whole scenario is the fact that this event is going to occur in two parts. There will be two distinct areas of low pressure traveling west the east along the front.

lets take a look.

This first image covers the next 12 hours. As we can see at the surface there are two areas of Low pressure along the front with a large ARCTIC HIGH northwest of Lake Superior over southwest portions of Ontario…. and a mild HIGH and the southwest Atlantic Ocean.

On the bottom left we have the humidity map and the dark green shows the precipitation at 12hrs or 7pm EST Sunday evening. The bottom right map shows the 850 temperatures. The main 850mb Low is over Northwest Iowa and I have highlighted in the purple Line the 0z degree isotherm which represents the rain snow temperature line. The Line is NORTH of DCA/ BWI. However much of Pennsylvania and New Jersey and southeast and NY appears to be cold enough to support snow as the precipitation comes east.

This Image is the NAM at 24 hours or 7AM Mondayt FEB 21. The map on the west side shows again the the precipitation as of 7:00 AM and the dark reign as the precipitation now moving across all of Pennsylvania & NJ and into far southeast NY and much of OH and WVA. NOTE… that the southern end of the precipitation shield over northern VA and central and sothern MD is weak with large gaps. And 850 temps have warmed considerably over MD and western PA and its juss rain over all of MD and the rain snow line as moved north of Harrisburg and is about to move north of Philadelphia. North central PA northeastern PA and Northern New Jersey into NYC appeared to be getting good snow.

　

Next this image is at 36 hrs  valid   of  7pm MONDAY Feb 22. The top map represents the SURFACE… and we can clearly see that the first area of Low pressure has now moved well out into the Atlantic and the second feature is coming through the Ohio Valley into northern portions of West Virginia.  Again I drew in the RED Line to show the Surface FRONTS.

The bottom left map is the RH map and the dark green shows the PRECIP has decreased significantly over PA NJ MD… but is on the increase over Ohio as the 2nd  Low develops.   The Bottom right map shows COLDER air has pushed back south behind the 1st Low… which often happens… but   only as far south as the MD PA Border.    To the south temps have stayed warm over VA and MD.

The data  clearly   shows  that ALL  portions of   Maryland — all of MD– is still  way  too  warm  for   ACCUMULATING SNOW.  Finally lets look at his map for the FEB 22 event the 2nd low is weakening and falling apart.  HPC’s snow graphic is absurd and totally unwarrented. 850 temps at DCA and BWI are  now finally cold enough to support all snow but the precip has ended OR is very close to ending.

 
FEB 23 .. significant SEATTLE snowstorm is LIKELY!    Euro is strongest with this but the 12z GFS and Canadian have this Low as well.
But this Low has MAJOR implications for the FEB 24-25 Low. The Seattle Low FORCES   a stronger Ridge to form over the southeast US (called teleconnections in the weather biz)  and this has will affect the FEB 24-25 Midwest Low.

FEB 24-25… The 12z EURO GFS and Canadian are on good agreement here that this next Major event will be strong Low that brings on a Midwest snowstorm.   Once again the wretchedly bad GFS has the Low at 120-126 and 132 hrs waaaaaaaay too far to the south and east given the overall pattern and the presnce of the Seattle Low .   The 12z Sunday GFS has this Low over southern WVA… western MD and into south central PA and over s NJ. The Euro has the Low passing over Erie.

Another MAJOR Midwest snowstorm is POSSIBLE FEB 27-28 with the Euro taking the Low through the Ohio valley into western NY state whereas the useless GDS has the Low over Richmond VA.

IS WINTER OVER FOR FOR THE EASTERN CONUS?

Posted by wxrisk | GENERAL | Friday 11 February 2011 11:14 pm

1630 HRS EST    FEB  11 

  
Given how warm the forecasts are next week for most of the CONUS east of the Mississippi River it is only natural to ask and wonder :  
” Is the Winter …over”.?      Well to answer that question we have to set some terms because we are dealing with large geographical regions with a exceptionally very climate in late February and March. 

If we set the premise of the   question to infer    whether not we are going to see another  sustained  severe cold   event    and/or  another significant East coast snowstorm… then I think I can safely say that the    Winter of 2010-11 is   “over.”      As you will see from these images there have been massive and  widespread fundamental changes in the entire pattern which precluded and returned to the sustained cold pattern we have seen for most of the winter so far.     And this new pattern also makes the potential for any sort of significant east coast snowstorm very unlikely. 

　 

Now that being said…. Lets make certain that every body understands what I am driving at.   I  did not say … “NO more cold or snow”.   Of course there is   going to be the additional snow and ice events between now and early April for New  England  and   the  Great Lakes areas.  

What I am talking about is the sustained cold winter pattern that the winter of 2010-11  is  now infamous for.      I am talking about every turn of the pattern which brought about six significant east coast winter storms.    I am talking about a Wibter pattern which brought several sub zero temperature air masses into the Texas panhandle for the first time in many years. 

So if we keep those events in mind as a reference point…    then yes  I am saying that the winter of 2010-11 is over   (Now that I have explained this in great detail I am certain to get a Post or email from some idiot weenie saying that this temperarures was 29 degree in northwest NJ and therefore Winter isnt over. Watch) . 

These next couple of the images clearly explain why the pattern has collapsed and what it means.    There has been a lot of talk on the various weather forms that the building positive height anomaly in the jet stream over the United Kingdom and Ireland …. which technically DOES count as a east biased -NAO …. would bring back the cold pattern .   The argument goes something like this :   Once the east baised -NAO moved towards iceland and Greenland in the last week February it would cause the whole pattern to shift back to a another round of below normal temperatures and potential stormy as over the eastern Conus. 

　 

It is a good fairy tale but it has little to do with reality. The problem is that the Ridge over the Ireland and the UK is NOT really a east based
-NAO.    Or if it is   a east Based -NAO   …once that  freature   moves east  towards   Scandinavia   is  no longer   a  east  based  -NAO 

　 

We can clearly see that on the initial atmosphere   500 MB  jet stream map from the European model this afternoon.    FEATURE A is the Block over the UK.  

    

By day 4 we can clearly see that the block is moved into Scandinavia and is no longer part of the NAO. This is now a Scandinavian block which is a totally different kettle of fish. 

 

It is possible that given enough time the Scandinavian block and retrograde back towards Greenland .   IF that were to happen that could trigger another – NAO which in turn would cause the entire pattern to shift . 

But as you can see the day 10 pattern from the European ensemble that is not gonna happen because the north American Polar vortex and the Asian polar vortex end up linking up into one Giant feature.      That is very bad  news  if one is  hoping  for a  return to     a  colder than Normal pattern   in the  eastern  half of the  Conus. 

                 

  

WHY FEB 10 IS NOT GOING TO BE A BIG DEAL

Posted by wxrisk | GENERAL | Tuesday 8 February 2011 8:04 pm

1900  EST  FEB 8

I  am getting a lot of questions as to why the this system which is coming in from the lower Plains and Mississippi delta is not going to become a significant east coast storm like so many Southern Systems have so far this winter.  So this is a good time to explain some of the points I have made over on  the facebook page in greater detail.
 
In my last post here on the web site I stated in no uncertain terms that I believe the threat for February 10 was a phantom threat    and  it  was NOT a serious East coast snowstorm.  I made that judgment based upon what I viewed as serious problems with the upper air pattern which is not conducive for an East coast snowstorm with this next system for February 10.
 
 
I have said this many times before in many different ways but this is a very good opportunity to show you exactly what I  am referring to when I say that east coast snowstorms are not going to occur simply because a weather model has a big L somewhere along the Georgia or Carolina Coast.  It doesn’t work that way.   ( hereafter called  SECS…  Significant  East Coast  Snowstorm).
 
This first image is  from the NAM Model  and it shows you the actual upper air map   from  late   this  Tuesday morning at  500 MB or jet stream level.  I have highlighted some important features   that  you need to beware of as you go through these maps.
 
Then I will compare this current map and situation with the two fairly recent major SECS  events:  the blizzard  of 26  DEC 2010 and  6 FEB   2010    DC to PHL   Blizzard.
 
In this first image you can see that the ridge is along the West coast of North America which is a very good position for those who like SECS.  You can also see the powerful upper air system over Arizona and Southern Nevada.  This system is pretty vigorous and it is going to bring a major snowstorm to portions of Oklahoma Kansas and Northern Texas and Arkansas.   Also what you need to notice it is the large powerful polar vortex which is situated over Eastern Canada.
 
It is a strong and powerful rule   or  guideline that the appearance of a large deep of vortex over Eastern Canada during the winter months is a NEGATIVE  factor for seeing large  SECS  events.   If you remember your basic weather science the more lines you have around the low pressure area the more winds  you have.  This is true with surface Low   pressure areas    whether you are looking at a coastal storm or hurricane and it is also true in the upper levels  of  the atmosphere.   In this case with this current setup for February 10 the large powerful polar vortex has  many  lines    or   500 mb height contours  around it.  And that means a lot of wind in a tightly compacted area.
 
To get a big storm  on the East coast and especially to get a major snowstorm you need to have the northern or polar jet stream MERGE  or PHASE with the southern jet stream.  It is this merging or phasing of the jet streams which is why the Low pressure area  over    the  southeast states comes up the coast. 
 
If the two  Jet streams do not merge   then most of the time the Low pressure area will slide off the coast and head out to sea.
 
In this next image at 36 HRS….  We can see the system that was over Arizona and Nevada is still looking fairly strong.  This is one of the reasons why those areas of   the lower Plains are going to see a significant snowstorm.     However the polar vortex is still very large and very deep and it is the large size of the polar vortex  which is forcing the polar jet stream to come way to the south.      I  have highlighted the southern jet stream in green and the northern jet stream in blue.   As you can see from the map the two jet streams are not merging at all.   If anything the blue  Jet stream is beginning to crusher  or overpower the green Jet stream.
 
 In this   3rd image at 72  hrs  the NAM  model– along with all the other model data– shows that   what  was  a   powerful shortwave or piece of energy in the jet stream is now being  crushed as it moves off the SE Coast.     No phasing is taking place at all and the large polar vortex has force the polar or  northern jet to plunge way to the south.
 
Now at this point some of you are asking…  Why do the jet streams phase some of the time over the eastern US and bring about a significant east coast winter storm and yet at other times they do not Phase ?
 
This is where the blocking patterns come into play over the  central and eastern Canada   and  Greenland.  Something has to force the jet stream to change their flow so they can interact and begin to Phase  or merge.  When there are large blocking features over Greenland or Eastern Canada or near Newfoundland for example…  the jet streams are forced to plunge southward or take unusual patterns and that greatly increases the chances of the two jet streams   Phasing  and thus allowing for significant east coast winter storm to occur!.
 
  Got  it?
 
Let’s take a look at the  great East Coast blizzard December 25-26.  I have presented 3 maps  from  DEC  24   25 and 26 all of them  500 MB  maps.
As you look at these maps it becomes readily apparent that the patterns are vastly different for the east coast them what we are seeing with this non event for February 10.
 
  DEC 24 we can see that we have no large intense deep vortex over the Eastern Canada of any kind.  There is no deep LOW with a  large number of contours  around it.  That is a major difference.  In addition we have a large ocean low centered over or near Newfoundland Canada which is often for to as the    50/50 Low.  And we had a massive block in the jet stream over Greenland  which is  a subtype of the  -NAO  ( item   #3) .    The   2  Blue  lines are two pieces of energy in the the northern and southern jet streams which are going to merge or phase and develop the huge East coast storm.
 
So the setup going into the  26  DEC   BLIZZARD  was totally different in every possible way when compared to the current setup for February 9 and 10.
 
On December 25 and 26…  The blocking features which I just talked about…   the 50 /  50 Low   and the  Greenland  Block  (-NAO) ….    is what forces the two pieces of energy   to  phase   into  the Monster  East coast storm.
 
In this next image   we can  look at the 500 MB  for  the DC  BWI   FEB 6 2010  Blizzard from almost one year ago….  And again that we quickly notice massive differences in the overall pattern.
 
There is no large deep polar vortex centered over central and Eastern Canada with numerous concourse around it.  There are a few areas Low pressure which have a few lines around them but that is not the same thing as what we see over Canada on with this next event  FEB  10.
 
We can see a very clear and very distinct  large ocean Low located  near  Newfoundland Canada  ( the 50/50 Low)   and we can see a massive about all blocking over Greenland once again….    and the LOW over   eastern  KY  is the  beginning of the massive snowstorm which hit Washington, DC Baltimore and Philadelphia.
 
 
Lastly we have the following event on February 10, 2010….  Which if you recall was another major east coast winter storm which bought another round of blizzard conditions to the areas from Washington, DC to Philadelphia.
 
First off we can see a huge block in the jet stream over Eastern Canada.  This is the exact opposite of seeing a large deep vortex over Eastern Canada which is what we have right now on February 10 , 2011. !!!!!  Once again we have a larger area of Low pressure located near  Newfoundland Canada….     And we had a rapidly developing system exploding over West Virginia moving into Virginia and Maryland which is going to cause the massive east coast snowstorm to develop. 
 
 
You have got to see that  it is  the pattern  that  determines the East coast snowstorm  chances . It is not a model that produces  the LOW   on the weather map.  If you don’t see this you are never going to be able to assess the overall pattern and snow storm potential with anything based  on  reality.
 
 One other point before close out this evening.  many of you  have been asking or wondering   is   the winter over the eastern half of the CONUS over?
 
There are several ways to answer the question.  First let me point this out.  If you think winter  continues until March 20/ the spring equinox then you are a moron.    That is when astronomical winter  end and spring  begins but that has nothing to do with   WEATHER   and   winter    weather  and spring weather  patterns inter ending and spring beginning.  Weather patterns.      The weather is  NOT  affected  by when  the sun crosses the tropic of cancer or Capricorn.  It has nothing to do with astronomy.
 
Undoubtedly the worst of the winter pattern is clearly over because even if the the pattern re-builds and we turn colder late February or March over the eastern half of the country …it still going to be very late in the season. 
 
Here is the European ensemble mean for day 9  and it’s a pretty darn warm looking map.  There is fairly deep trough over the Pacific Northwest which extends down into California and a fairly strong ridge over the southeastern U.S.   At the surface  there is a strong area of High pressure off the SE   coast    mild air  dominates the country the east of the Rockies.
 
This next image gives us an eight better interpretation of what the pattern and temperatures going to look like on February 18.  The bright greens and yellows are pretty warm temperatures.  In VA    850 temps are …  according to the European ensemble..   at  +6  or  +7c….  And were bright sunshine and westerly winds that gives us  +10c.  Add  11C  for Mid FEB=   21c which is around 70°.
 
This last image shows you the overall hemispheric map and we can point out some important features here as well.   Item  #1 represents blocking which has developed over Scandinavia and the area north of Great Britain.  This may or may not be a  east  based   NAO….  But it can also be counted as a Scandinavian block which is a totally different feature.
 
Item 2 represents the polar vortex which has according to the European ensemble at day 10 become aligned in a west east direction .  That is very bad news for those like cold conditions and very good news for those who like mild conditions  over the central and eastern US.   Item  #3  is the west coast trough…  And all these features together support item #4   which is the southeast ridge. 
 
Finally  the  only did mechanism which I can see  which might change the pattern as we  go into the  end  February or early March …is the the deep Polar Vortex over Japan.  If this feature moves east and stays south of Aleutian  islands it would if cause a strong ridge to form the jet stream over Western Canada and fundamentally  change   the entire pattern.  Of course there  is no guarantee or certainty that this feature is going to move and it could stay  for several  weeks.

GROUND HOG DAY 2011– is winter over in the NE?

Posted by wxrisk | GENERAL | Wednesday 2 February 2011 7:12 pm

1355  PM  EST   FEB 2

Well today is one of the great days of the year–   it is groundhog day which has been one of my favorite days of the year since I was a kid.  After I fell in love with the weather I would celebrate groundhog day by going into the the local boy scout     and wild life  area in the suburbs of Philadelphia and spend the day  looking for groundhogs and eating sandwiches  of cream chesse &   jelly and  / or  Ham sandwiches  and drinking iced tea .

When you are 12   13 and 14 years old life simply doesn’t get any better.   Of course today I get to watch the the second greatest movie of all time    GROUND HOG  with Bill Murray.
The real surprise with the Midwest   Blizzard is that the dry slot of this intense storm was totally missed forecasted by all the short range models.  The model data even yesterday afternoon show that the dry slot would not make it much further to the north and east   then Central Indiana and east central Illinois  around the towns of Decatur and Champaign and Danville.  Instead as we now know the dry slot punished all the way through to the Indiana Michigan border.  Locations  to the  south side of Chicago such Kankakee   saw 50% less snow  then Midway .

Here  in   South Central Virginia the temperatures did crack the 70  degree mark   but the cold front is rapidly sweeping through Central Virginia   so the fun  is about to end.

Already I  am being asked questions as to whether not the winter is over here in the the lower Middle Atlantic states.   For    the folks  in  Central Virginia as well as the Piedmont and southwest Virginia …the winter has yet to begin.   Still that question  –IS  WINTER  OVER ?–   is a tricky question because it mains a lot of different things to a lot of different people.

First of course the winter is not over even in areas which have not seen a lot of snow in Virginia.  And it certainly is not over in the northeast US.   On the other hand as is current Midwest storm clearly shows and this next event on the  East coast    this  weekend the overall pattern is vastly different now than what it has been for the past eight weeks . 

Therefore while it is way too early to say the winter is over in the Northeast Friday… One can say   that  the active…cold and stormy pattern that has pounded the Northeast with six major winter East coast storms has come to end.    That part the winter is over.

Now that does  mean   the  NE  US is NOT   going to see any more  good snow in the big cities of the northeast or the interior.  That is not what I am saying even though I am certain that some idiot  weenie is going to miss quote me.   What I am talking about is the pattern which produced several significant if not massive East Coast storms summer which qualified as being historic Northeast us snowstorms   (  KU  events).   If we keep  just THAT  the criteria  in mind   then   I can  say with some confidence ….THAT  pattern is over.

The event coming this weekend is almost a complete rain event for almost everybody  in the  Big cities  of Northeast.  Only over WVA… western MD central PA    into central NY state will this event on February 5 bring any sort of snow .     Behind this system we  are going to see another pattern amplification with the mean trough developing over the Mississippi Valley and another significant Low pressure area  that forms over the Delta  and   trascks Northeast  into the Midwest  and the eastern Great Lakes… FEB 7.  

        

Behind  this  Midwest Low  another massive arctic air mass is going to plunge  out of Western Canada down the east side of the Rockies and the Plains and once again  move into  the Lower Plains   and the Deep South by February 9 – 10.

In doing so both the European and the  GFS are taking a piece of energy in the jet stream and trying to develop some sort of coastal storm February 9 – 10 .

The 0z euro  operationally  has   a  Low that would develops off  the   North  FL  coast and    bring    heavy snow to   eastern NC   and se VA but  miss   central  VA and RIC– again!!!! –  by  50 miles or less.


This idea is supported   by the 0z GFS.  But the  6z  gfs  has no such Low at all… and Most of the GFS and  Euro  ensemble do NOT either.

 

 The New   12z   EURO  is even more  promising for a  deep south Major snowstorm and one that would bring  major   snows over   most of  NC and   central/ eastern  VA….


Even though these maps look   very promising… the problem is that the overall pattern Eastern Canada and Greenland do not support this sort of storm development.  Yet the model data looks really interesting…  and it is gonna be cold enough.  But I am skeptical of this whole set up until     the pattern over eastern North America and Greenland changes.
The   Teleconnection Indicies show the   SUPER    + NAO  shifting back to Neutral  but the   wretched   GFS is   going  Bonkers and    rapidly  developing a  -NAO.  As you can see  from this Link  the   GFS  is over doing this when compared to the  other  models.