Weekend Threat 12/14-12/15

[MJO812]

The bananna highs up north are in a good spot.

[IsentropicLift]

00z GGEM looks improved

 

[ace0927]

The bananna highs up north are in a good spot.

the 850 low is about 450 miles to far west and it doesnt even transfer to the coast in time for boston.

[snywx]

The NW crew would love this....

 

96hrs..

 

 

 

 

[IntenseBlizzard2014]

The NW crew would love this....

 

96hrs..

 

I bet HR 102 is pretty nice between I-287 and I-80. 

[snywx]

I bet HR 102 is pretty nice between I-287 and I-80. 

[patrick05]

reading in the SNE forum, ECMWF is southeast of 12Z and has a stronger high as well... anybody willing to post details and how it correlates to us here??

[Allsnow]

00z euro is colder and all snow. It's also weaker with everything. A good amount of over running snow.

Snow maps are 4-6

[Zir0b]

hmm I think the Euro's SW bias is at play here...seems to leave behind a piece of shortwave energy in the Southwest resulting in a less phased, weaker system. Thoughts? 

[MJO812]

0z Euro phased a little later but it's a cold solution for our area and all snow. The high was further south on this run than the 12z run.

[WE GOT HIM]

0z Euro phased a little later but it's a cold solution for our area and all snow. The high was further south on this run than the 12z run.

Yea it has some mixing still at hour 108 or so, but definitely colder

[MJO812]

Yea it has some mixing still at hour 108 or so, but definitely colder

Much more progressive than the 12z run.The Euro is much colder than the other models.

[WE GOT HIM]

Much more progressive than the 12z run.The Euro is much colder than the other models.

Its a possible solution especially given the pattern, so we have to wait and see.

[IntenseBlizzard2014]

I bet HR 102 is pretty nice between I-287 and I-80.

I guess it looks more "ice" than nice.

[PB GFI]

The 0z euro, Its colder at the surface and may have a better handle on the placement of the  HP that gets into NE 48 hours

before the precip breaks out  ,

So its drilling cold air further south .

[PB GFI]

The GFS and NAM are much flatter with the cold  shot into New England , and is more zonal at 72 hrs , where is the Euro is much more aggressive

drilling low level cold air all the way down to the Mason Dixon line . I don't know who s gona be right , but I know who I think is right

[SnowGoose69]

hmm I think the Euro's SW bias is at play here...seems to leave behind a piece of shortwave energy in the Southwest resulting in a less phased, weaker system. Thoughts? 

 

I looked into that yesterday, it does not appear to be the case, the Euro is holding another shortwave way back in the SW off AZ/CA at 90 hours but that is not one of the waves responsible for this system, at 78 hours both the Euro/GFS show the main shortwave for this storm over WRN OK and NRN TX in the same place..the one thing I did notice is that both the models are fairly neutrally tilted with the disturbance over the SRN Plains til after it passes Arkansas, often times thats an indication you're not getting a coastal or inland track on a storm, thats a very good rule DT presented at a conference a few years ago, even if the model shows an inland track or over the coast track, a neutral or positively tilted shortwave reaching the Miss River more indicates an offshore track.

[REDMK6GLI]

The GFS and NAM are much flatter with the cold shot into New England , and is more zonal at 72 hrs , where is the Euro is much more aggressive

drilling low level cold air all the way down to the Mason Dixon line . I don't know who s gona be right , but I know who I think is right

From what im seeing i think ECMWF has the right idea in my opinion. Think they're will be more cold air at all levels than what is currently depicted on the models. This season models has consistently underforecasted cold air and i think the depth of this cold coming this weekend will hold strong

[REDMK6GLI]

I looked into that yesterday, it does not appear to be the case, the Euro is holding another shortwave way back in the SW off AZ/CA at 90 hours but that is not one of the waves responsible for this system, at 78 hours both the Euro/GFS show the main shortwave for this storm over WRN OK and NRN TX in the same place..the one thing I did notice is that both the models are fairly neutrally tilted with the disturbance over the SRN Plains til after it passes Arkansas, often times thats an indication you're not getting a coastal or inland track on a storm, thats a very good rule DT presented at a conference a few years ago, even if the model shows an inland track or over the coast track, a neutral or positively tilted shortwave reaching the Miss River more indicates an offshore track.

Very good point snowgoose. My feeling is this primary is going to die off faster than expected making the secondary develop and move further off the coast than currently forecasted

[Storm At Sea]

Indeed. H5 stays positively tilted. Also, another entity that I always keep an eye on is 850 mb low. regardless of SLP placement, if you get a closed 850 mb low heading to CLE, PIT, or BUF, you'll almost certainly run into mixing problems in the I-95 or simply a switch to rain. Ideally, one wants to be 150 miles or so NW of the 850 mb low. That tends to be where the best CCB snows set up. FWIW, 6z NAM shows a setup that would likely lead to quite a SECS. At 84 hrs, the H5 energy is just starting to get involved, there's a decent supply of cold air to work with, and the there are indications of a 850 mb low developing over GA.

 

I looked into that yesterday, it does not appear to be the case, the Euro is holding another shortwave way back in the SW off AZ/CA at 90 hours but that is not one of the waves responsible for this system, at 78 hours both the Euro/GFS show the main shortwave for this storm over WRN OK and NRN TX in the same place..the one thing I did notice is that both the models are fairly neutrally tilted with the disturbance over the SRN Plains til after it passes Arkansas, often times thats an indication you're not getting a coastal or inland track on a storm, thats a very good rule DT presented at a conference a few years ago, even if the model shows an inland track or over the coast track, a neutral or positively tilted shortwave reaching the Miss River more indicates an offshore track.

[kpantz]

Indeed. H5 stays positively tilted. Also, another entity that I always keep an eye on is 850 mb low. regardless of SLP placement, if you get a closed 850 mb low heading to CLE, PIT, or BUF, you'll almost certainly run into mixing problems in the I-95 or simply a switch to rain. Ideally, one wants to be 150 miles or so NW of the 850 mb low. That tends to be where the best CCB snows set up. FWIW, 6z NAM shows a setup that would likely lead to quite a SECS. At 84 hrs, the H5 energy is just starting to get involved, there's a decent supply of cold air to work with, and the there are indications of a 850 mb low developing over GA.

I know it's the NAM and all, but it looks markedly better (in terms of producing something worth tracking) than the GFS at 84 hours.  You can see the northern stream energy digging in at 500mb whereas on the GFS it's already closed off and further northeast.  Energy is still flowing into the system.  Personifying a bit, but the NAM has the look of a system building energy as it approaches the coast instead of just letting it leak out like the GFS does.

[Weathergun]

There's more support for the coastal low to take over sooner, with it being in the right-entrance region, of 160kt+ upper-level jet streak:

[NEG NAO]

6Z GFS has a very borderline situation developing for later Saturday into Sunday in the NYC metro - very difficult to try and pin down precip type this far out and how much of each type.

 

http://wxweb.meteostar.com/sample/sample.shtml?text=KEWR

[earthlight]

I know it's the NAM and all, but it looks markedly better (in terms of producing something worth tracking) than the GFS at 84 hours. You can see the northern stream energy digging in at 500mb whereas on the GFS it's already closed off and further northeast. Energy is still flowing into the system. Personifying a bit, but the NAM has the look of a system building energy as it approaches the coast instead of just letting it leak out like the GFS does.

The NAM definitely leans more towards the Euro, especially with its handling of the northern stream feature. Speaking to your point, that northern stream trough is very important and can change the game when it comes to this set up. It really is a reinforcing shot of arctic air, but its placement and orientation will be a major player in where the primary surface low tracks and how strong the high pressure system is to the north.

The GFS being more disconnected means that, despite having some southern stream energy which digs farther south, it becomes mostly a WAA driven event. And the polar energy that drives southeast eventually just compresses and elongates the southernmost energy.

The wave spacing and timing on the Euro and long range NAM is much more favorable for something wintry around here.

[kpantz]

The NAM definitely leans more towards the Euro, especially with its handling of the northern stream feature. Speaking to your point, that northern stream trough is very important and can change the game when it comes to this set up. It really is a reinforcing shot of arctic air, but its placement and orientation will be a major player in where the primary surface low tracks and how strong the high pressure system is to the north.

The GFS being more disconnected means that, despite having some southern stream energy which digs farther south, it becomes mostly a WAA driven event. And the polar energy that drives southeast eventually just compresses and elongates the southernmost energy.

The wave spacing and timing on the Euro and long range NAM is much more favorable for something wintry around here.

The 500mb evolution is what I'll be focusing on as the 12Z runs roll in.  That seems to be the keystone to this whole thing in terms of whether it blows up or not.  Speaking of blowing up, did anyone read the extended disco from WPC?

 

 

 

...MAJOR WINTER STORM THIS WEEKEND FROM THE CENTRAL APPALACHIANS

TO THE NORTHEAST...

...SHARP ARCTIC OUTBREAK FOR THE UPPER MIDWEST SUNDAY AND MONDAY...

RELIED ON THE 12Z/10 ECMWF FOR THIS FORECAST PACKAGE, WHICH SHOWED

A STRONG POSITIVE CORRELATION WITH BOTH THE ECENS AND CMCE MEANS

FROM THAT DATA CYCLE, AS WELL AS THE 00Z/11 GFS. THE MOST CRITICAL

REGIONS IN TERMS OF MODEL SPREAD VIS-A-VIS SENSIBLE WEATHER

THREATS ARE THE MIDWEST AND EAST COAST, WHERE SEVERAL SHORTWAVES

ARE EXPECTED TO CONVERGE. THE DISJOINTED NATURE OF THE COMPLEX

FLOW PATTERN EVOLVING OVER THE EASTERN HALF OF THE NATION THIS

WEEKEND MAKES FORECASTING WHERE SPECIFIC HAZARDS WILL OCCUR QUITE

DICEY. THE INTEGRITY OF THE COLD AIR BANKED FROM THE GREAT LAKES

TO NEW ENGLAND IS CRUCIAL FOR PRECIPITATION TYPE. THE DUMBBELLING

OF MID-LEVEL VORTICES WILL DICTATE WHERE MOISTURE WILL CONVERGE

AND WHERE DRY SLOTS WILL BE FORCED. AT THIS POINT, THE MOST LIKELY

DETERMINISTIC OUTCOME WOULD BE FOR A TRANSFER OF SURFACE LOW

PRESSURE FROM THE OHIO VALLEY TO THE MID ATLANTIC COAST SATURDAY

NIGHT, WITH A SUBSEQUENT BOMBING OF THE ATLANTIC LOW AS AN ARCTIC

VORTEX PLUNGES INTO THE GREAT LAKES SUNDAY AND SUNDAY NIGHT. THE

PRECISE INTERACTION BETWEEN THE GREAT LAKES VORTEX AND THE NEW

ENGLAND COASTAL LOW WILL DETERMINE HOW SEVERE THE WINTER

CONDITIONS BECOME OVER THE NORTHEAST--AND HOW CLOSE SNOW AND ICE

GET TO THE MAJOR CITIES FROM WASHINGTON TO BOSTON. ANOTHER

ATLANTIC COASTAL LOW AT THE END OF PERIOD--NEXT WEDNESDAY--COULD

REINVIGORATE WINTER WEATHER FOR THE NORTHEAST METROPOLITAN

CORRIDOR.

[REDMK6GLI]

The NAM definitely leans more towards the Euro, especially with its handling of the northern stream feature. Speaking to your point, that northern stream trough is very important and can change the game when it comes to this set up. It really is a reinforcing shot of arctic air, but its placement and orientation will be a major player in where the primary surface low tracks and how strong the high pressure system is to the north.

The GFS being more disconnected means that, despite having some southern stream energy which digs farther south, it becomes mostly a WAA driven event. And the polar energy that drives southeast eventually just compresses and elongates the southernmost energy.

The wave spacing and timing on the Euro and long range NAM is much more favorable for something wintry around here.

Earthlight your always very informative and explanitory in your analysis and is a great read. Me personally i think the NAM and EURO have a better idea as to what is going to happen this weekend. The cold air mass is going to be one the stronger/potent ones this season and also i dont think the primary is going to be going to buffalo and will probably die off well before that. Either way this week is going to be fun to finish out and the 12z/18z suite today should be bringing some more light to this forecast in a more definitive way

[REDMK6GLI]

The 500mb evolution is what I'll be focusing on as the 12Z runs roll in. That seems to be the keystone to this whole thing in terms of whether it blows up or not. Speaking of blowing up, did anyone read the extended disco from WPC?

Looks like WPC is recognizing the potential here. I just hope this isnt a ice storm and they are miserable and dangerous. I think the models will be little by little adjusting the cold air into the system as in making each following run colder. This cold snap looks like its headed straight for the great lakes/NE

[Superstorm93]

Looks like WPC is recognizing the potential here. I just hope this isnt a ice storm and they are miserable and dangerous. I think the models will be little by little adjusting the cold air into the system as in making each following run colder. This cold snap looks like its headed straight for the great lakes/NE

 

 

[kpantz]

They did say they were following yesterday's 12Z Euro, so what they drew up isn't much of a surprise...

[IsentropicLift]