1400  EDT MARCH 31

all the Models  at 12z  have shifted    EAST…  all of them…     the  heavy snow  threat for ne PA and south central  NY state is  much reduced..
The 12z   THURSDAY MARCH 31   euro  is also waaaaaaay  East   with this Low

recall what I said in the   INTIAL  discussion 

The complicating factor in this upcoming event happens to be a significant piece of energy which is coming in behind the shortwave  over the  Southeast US.   We can see this piece of energy on the models   HERE.  This feature is referred to in the weather business as a upstream kicker….  Because as this feature approaches rapidly from Southern Canada into the upper Midwest it ends up affecting the system over the east coast of the us by forcing it or dislodging it to the east.

Badda  Boom Badda  Bing

LAST CALL  …..

1445  EDT    MARCH 30

1ST CALL

1845   EDT   MARCH 29 ….

click on ALL the images  for  FULL  size

1ST   GUESS   

For those of you that do not follow  WXRISK.COM over at the Facebook page…   and you really should…   I have been talking about the potential for significant East coast LOW   since March 23.    Last week I was concerned that this might be a inland storm tracking up the Appalachian Mts and providing a severe weather threat for the southeastern states and the Middle Atlantic region.     Of course that  is clearly not gonna be the case…  and I stated  as much on  back  on 3/26  and   3/27 over at the  FB  page.

There were  two  main reasons  WHY I have been so bullish about this event.    First because of  the    very strong  GFS and  European model  ensembles  in  the 11-15  day.    Second because of the strong indications   the  -NAO   would   shift its     phase  in a dramatic and powerful movement: shifting rapidly from being strongly   negative   to being strongly positive in a very short period of time.    Research done several years ago at  SUNY  by  Heather  Archambault   showed  that whenever  the  NAO  shifts  strongly and rapidly from one phase to the another   ….IF the overall pattern is  set up right over the eastern US…  there can be a significant  or Major  East coast Low.

Of course there are still a lot of questions to be answered with regard to this potential system.  There been some other   forecasters  and  informed  weenies   talking about a major snowfall of getting into NYC and  even into Philly   but  I really do not agree with that scenario/ forecast.
What causes the coastal storm to develop is a strong piece of energy in the jet stream  (callesd a shortwave in the  weather  biz)   which is going to develop in    ”negative tilt”   on March 30-31   as it approaches the southeastern U.S. region.  This negative tilt  –  the  short wave runs  NW to SE in its alignment — is a strong signal   that meteorologists look for when considering the potential for a significant coastal storm to develop.

The complicating factor in this upcoming event happens to be a significant piece of energy which is coming in behind the shortwave  over the  Southeast US.   We can see this piece of energy on the models   HERE.  This feature is referred to in the weather business as a upstream kicker….  Because as this feature approaches rapidly from Southern Canada into the upper Midwest it ends up affecting the system over the east coast of the us by forcing it or dislodging it to the east.

The  Tuesday morning the  0Z  GFS  had  the coastal Low  OVER NYC  …inland of the    coast.    This of course would mean  a widespread significant rain for all of the Middle Atlantic Coast as well as NYC  and  coastal  New England and any snow would be restricted way inland into the mountains of Pennsylvania and New York .      The 0z  GFS  ensemble mean was further  East.

BUT…  the GFS shift of the Low to the east at  6z  and again at  12z .    This resulted in the GFS  model forecasting widespread significant snow into Philadelphia metro area… the Lehigh valley most of New Jersey and NYC   in  the amounts of 6 to 10 inches.    The   GFS ensemble  mean   seems to to support this   East shift.

The   CANADIAN shows the same sort of shift between its early morning  0z  run  and the  12z  Tuesday run.     As you can see initially the Canadian model from early this morning had two areas of low pressure along or  just off the East coast and the model was trying to consolidate then into one big system.    This is a warning sign that  the forecast for a major east coast storm    COULD  be  in  trouble because invariably the weather models always take these merged Lows   and pull them back to the too far the west .  

The 12z   CMC   solution is a bit further to the east and closely matches the  12z  GFS.

 
The    0Z  EURO does develop    a major East coast storm but   the  0z Model run did  so  in such a way that the  Low  swung out  way to the East  then comes  back towards Boston.    The Low’s  “bombs out  ”      east of Boston in the Gulf of Maine which would bring heavy snow to Eastern New England but would not do much for NYC and New Jersey of  for  Eastern New York. 

This idea was supported by the European ensemble.

The 12z  euro takes the coastal Low  much closer to the coast and matches  again the  12z   GFS  and   12z   CMC .

  At this point all the 12z  operational models on this Tuesday afternoon appear to be in strong agreement .   The European model again shows rain   for NYC and all of   eastern Long Island.  IF you get either the the European MOS or a large high resolution graphic of the model ….  you  will  see that the 850 temperatures are above zero for about half the  event  in NYC.  Clearly this implies  heavy rains  for significant portion of the storm but areas just to the north and west would probably stayed mostly snow.      The European model implies a major snowstorm for much of the Hudson Valley including Albany and a large portion of central and interior Eastern New England with Boston and southeastern Massachusetts staying rain for significant portion of the event.
What I find most impressive is the model agreement that the system is going to stall in the Eastern Gulf of Maine which is why I think much of Maine as well as southern half of New Hampshire  much of Massachusetts will see the major snowfall.

The complicating factor in this upcoming event happens to be a significant piece of energy which is coming in behind the shortwave  over the  Southeast US.   We can see this piece of energy on the models   HERE.  This feature is referred to in the weather business as a upstream kicker….  Because as this feature approaches rapidly from Southern Canada into the upper Midwest it ends up affecting the system over the east coast of the us by forcing it or dislodging it to the east.

 1st   CALL  ( latest forecast)

 1ST  GUESS   INITIAL   FORECAST

0001 MARCH   23….

 The  Trend   is  MY  friend….  

 1630  EDT  MARCH 22 

In the autumn of 1944 when the western Allied offensive across France and the low countries began to run out of steam  ( along with much more imposing terrain and stiffening German resistance )   Adolf Hitler planned a surprise counterattack which is euphemistically referred to as the battle of the bulge.  Historically it is known as the 1944  Ardennes offensive.

As a active and longtime war gamer   I have several computer games on the 1944 Ardennes  counter offensive  as well as several wargames of  varying complexity and size.  The fact of the matter is that I own every single   game on the Battle of Bugle that has   EVER  has ever been published and I think I own almost every single historical  work  on the battle.
While some are you may find this very interesting many of you  are probably wondering why I am talking about this battle in the latter portions of WW2.  Well there  is a method to  my  madness and has to do with the idea of a supposed beaten   or  defeated  enemy that launches  a surprise counteroffensive.  You see   that is essentially what old man winter is doing with this current pattern.  And  like the Ardennes’ offensive of 1944  …which really  was just a  a play for time…  This current surge of winter weather coming into the eastern US s and especially the Northeast US…. is the last dying gasp of a collapsing empire.

The 1ST GUESS and 1st CALL MAPS are out and I presume a lot of people have already seen them.    The main difference between the the maps has to do with the amount of snow that im forecasting for central and Northern New England.  

  I was somewhat uncertain as to how much of the snow shield is going to get into these areas of New England but based upon the latest data… It seems reasonable to extend the 2-4″ band of snow further to the North.     The GFS has a lot more snow than I do over northern VT and NH but I am having a little trouble figuring out how the significant or heavy snow is going to get THAT far to the north given the track of the 850 Low and the the precip shield .   Keep in mind that this is not a coastal storm that a powerful Midwest low which is tracking east from MN/ IA into MD.

I have totally rejected the last few runs of the operational NAM model in the depiction of significant snow getting into northern Philly area. Clearly in the metropolitan Philly area will see some snow and the northern end of Bucks and Montgomery County could see or 3 ” .     But that is NOT what the NAM is showing.     Some of the recent   runs   of the NAM have been showing 6-10″ over Southeast Pennsylvania and that clearly is not going to occur.

Weather models can say this or that…. they can say ABC or XYZ.     One of the real easy to grasp basic rules  of synoptic meteorology is that ANY time a closed well defined 850 mb Low tracks to your NW then N then NE and YOUR location is south of the 850 Low… well you are going to see 850 mb temps warm with each new model run.

We can see that happening here with the 0Z TUESDAY NAM 850 Low/ temps at 48 hours … Valid 8pm EDT 3/23 and compare that to the 12z TUESDAY NAM 850Low/ temps …Valid 8PM EDT 3/23.   This Image clearly shows the problem the NAM has…. And even though some of the out of controls snow knots in the Philadelphia area have ignored this.    The complication and the problem however is real.   The 9z TUESDAY NAM has the 850 Low passing N and W of PHILLY but the Model shows little warming.    That is Just BS..

Sure enough when the updated run of the NAM came out at 12z today 850 temps at + 4 degrees C warmer!!!

All that being said it is still possible that NYC could end up seeing a little more snow than the current forecast that I have. I would not at all be surprised if Staten island and JFK saw 1 or 2 inches of snow and the northern Bronx saw 5″ .

The other KEY point I wanted to make here is that we are not dealing with the heart of winter. Its LATE March and each passing day it becomes harder and harder to get the snow levels to the coastal areas and the big cities of I-95. If this event war was going to occur in DJF than PHL into central & southern NJ.. NYC and Long Island and coastal Mass and CT… could get Blasted.

Indeed to take a look of the actual surface map for Tuesday night and Wednesday you will  notice that the large arctic HIGH which anybody’s been talking about is in a terrible location. The HIGH is large and strong ranging from 1044 MB to 1060 MB but it is far to the north of Hudson’s Bay!    The HIGH is really over Baffin island and that is very far away ( and would be a problem even if this was JAN 22)

MARCH 28-30

 
It pretty clear now that there is gonna be some sort of MAJOR event coming out of the weekend or early next week over the Middle Atlantic states.    The first event may just be a light overrunning event of rain or rain/ snow mixed on the 27th and 28th as weak Low tracks along the stalled front over NC and TN.    Yesterday this event looked more significant but all the model data here on the 22nd appears to be downplaying this event.

Instead the main feature happens to be very strong piece of energy in the jet stream coming out of the central southern Rockies ay DAY 6 (3/28).    We can see all of the ” players” on this day 6 European weather model Image .

Note that the large arctic HIGH which is over currently located north of Hudson’s Bay Canada… begins to move south and east.    This is going to drive a lot more colder air deeper into the heart of the Midwest and the East coast    . The DAY 6 European show this Nicely. 850 temps are -8c at DC -10c over NYC and -4c over RIC.     In addition we see a large Upper Low in the Jet stream over eastern Canada that moves into southeast Canada by day 6-7.     This becomes the classic 50/ 50 Low.

What is more impressive is that the overall atmosphere pattern over the northern hemisphere  is NOT   currently showing any sort of feature that could be called a large polar vortex (the PV) which is typically found in the winter and spring months over central and Eastern Canada.    Instead what we have is the block in the jet stream over Central Canada.   The lack of any sort of vortex over the northern hemisphere strongly favors that ANY Low coming off the East coast is likely to undergo significant intensification and could become a major coastal storm.    That is exactly what the models are showing happening on March 30 with this next system.

The European model was showing a significant snowstorm for much of Western Virginia   (SHENANDOAH)    as well as portions of   West Virginia central and Western Maryland including possibly the DC and Baltimore metro areas and as far north as Philadelphia.     This scenario is supported by the 12z Tuesday GFS as well… And some of the varies ensemble members are also leaning in this direction.

Although I am confident that we will see another major coastal storm over the next 10 day I am still uncertain as to be exact timing of this event. Right now the models clearly indicating March 30 but it might end up being closer towards the APRIL 1-2.

 this links opens   up in power  point  presentation….

http://tinyurl.com/4rxu5yh