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February Pattern and Storm Discussion


POWERSTROKE

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Is it my imagination, or are the 0, 6 and 12 Z GFS, and the O Z Euro, trending a bit warmer for this system than yesterday's runs?

Seemed less sustained, and more side swipey to me :)  Still, the last Doc I saw had the 0 line into Fla, and that's what I look for on both models, to see some freezing around here.  I'd like to see some shots into Miami for some good strong cold, but it looks like the models are looking out past a week and throwing up their hands and going Whaaaaa?  There was at least a shot at some cold and flurries down to you the other day, and I'm not seeing that now :)

  I'm watching Mon/Tues time frame, just because it's close and if the atmosphere is really changing, we'll start seeing close calls....and around March 2/3/4 for that Mole gom low.  I think the timing would be right, if the blocking sets up and the trough is back west enough, and the cold isn't too severe.  I don't mind not having a storm again, or having a confused look for then on the models, as 3 or 4 days out is the proof of the pudding, not ten days out.  If the cold air drifts away, or gets way colder and dried up, we could just enjoy some record cold, and have to wait for it to relax.  Meanwhile, if things are changing we'll see it 3 days out, not two weeks out, as far as something to get excited about, lol.  The trends are propitious, but something could actually happen early next week, and beyond that is just mist and phantoms, and tales of great deeds :)  I just know I don't want to see the trough setting up east of Ga. and getting little or no cold, lol.....and it's already cutting out west Ala from the good cold, in one run.   As long as the long range stays cold, I'll wait patiently until it's within three days to look for the storm.  Tony

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JMO the Euro was not too far off. Obviously we want a CMC solution but it wouldn't take much for the Euro to lean towards that. Given how progressive the Euro is with energy coming out of the west it would make sense that it would just scoot it out. Still has potential me thinks. 

 

6 of 12 GFS Ensemble members on PSU Ewall from 12z showed at least some snow over portions of the SE with the 6-8  day system.  The CMC was actually keying on a follow-up wave in the 8-10 day range...what the heck, let's go ahead and close out winter talking about individual storms in week 2   :bag:

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I've read in a couple places that the models may not be able to pick up the individual vorts that will be floating around at this range, that one of them will amplify, or generally the smaller details won't materialize until later.  Very good stuff for a weenie like me, I'm all over that.  Models wrong, show snow later!! check. 

 

I guess I'd give it till Monday or Tuesday.  If a storm or two is not pinging off a run or two on the GFS or EURO, be tough to buy in to it.  CMC was just superb though looking at the track.  Classic; for CLT anyway. 

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Good write-ups from CPC, IMO…

 

 

6-10 DAY OUTLOOK FOR FEB 27 - MAR 03, 2013

 

TODAY'S ENSEMBLE MEAN SOLUTIONS REMAIN IN REASONABLY GOOD AGREEMENT ON THE 
500-HPA HEIGHT PATTERN OVER NORTH AMERICA, WITH SOME DIFFERENCES AMONG THE 

ECMWF(EC)/CANADIAN MEANS AND THE GFS ENSEMBLE (GEFS) MEAN. THE EC/CANADIAN 

ENSEMBLES SUPPORT A LARGER RIDGE FARTHER WEST ACROSS NORTH AMERICA, WHILE THE 
GFS ENSEMBLES ARE MORE PROGRESSIVE IN THE EASTERN PACIFIC RESULTING IN A MEAN 
RIDGE POSITION CLOSER TO THE ROCKIES. IN TODAY'S OFFICIAL 500-HPA HEIGHT BLEND, 

THE GEFS IS WEIGHTED SLIGHTLY MORE THAN THE OTHERS DUE TO BETTER OVERALL SKILL 

DURING THE LAST 60 DAYS. ADDITIONALLY, GOOD RUN-TO-RUN CONTINUITY AMONG 

OPERATIONAL RUNS PROMPTED A LARGER THAN AVERAGE WEIGHTING IN THE MANUAL BLEND

THE FORECAST CIRCULATION IS STILL DOMINATED BY A -NAO BLOCKING PATTERN OVER THE 

WESTERN ATLANTIC AND EASTERN NORTH AMERICA, CONSISTING OF AN EXPANSIVE AREA OF 

MUCH-ABOVE-NORMAL HEIGHTS FROM NEAR HUDSON BAY EASTWARD TO NORTHERN EUROPE, 

SOUTH OF WHICH THERE IS A ZONALLY-ORIENTED AREA OF BELOW NORMAL HEIGHTS FROM 

SOUTHEASTERN NORTH AMERICA TO SOUTHWESTERN EUROPE.

 

THE GREATEST PROBABILITY FOR BELOW-NORMAL TEMPERATURES IS FORECAST OVER THE 

SOUTHEASTERN QUADRANT OF THE CONUS. THIS AREA IS FORECAST TO EXPERIENCE 

ANOMALOUS NORTHERLY FLOW BOTH AT THE SURFACE AND ALOFT. MILDER-THAN-NORMAL 

TEMPERATURES CONTINUE TO BE FAVORED ACROSS MUCH OF THE NORTHERN TIER OF THE 
CONUS DUE TO WARM AIR ADVECTION ASSOCIATED WITH A MAJOR STORM SYSTEM EARLY IN 

THE PERIOD AND A LACK OF TYPICALLY-COLD AIR OVER THE CANADIAN SOURCE REGION TO 

THE NORTH. THE BLOCKING PATTERN OVER EASTERN NORTH AMERICA FAVORS A STORM TRACK 

NEAR OR JUST OFF THE EAST COAST AND DRIER-THAN-MEDIAN CONDITIONS ACROSS MUCH OF 

THE WEST-CENTRAL CONUS UNDER NORTHWESTERLY FLOW ALOFT.

 

 

8-14 DAY OUTLOOK FOR MAR 01 - 07 2013 

 

THE ENSEMBLE MEAN SOLUTIONS INDICATE THAT THE CIRCULATION PATTERN FOR WEEK-2 

WILL REMAIN VERY SIMILAR TO THAT FOR THE 6-10 DAY PERIOD, EXCEPT WITH SOME 

EVOLUTION OVER THE EASTERN PACIFIC AND FAR WESTERN NORTH AMERICA. THE BLOCKING 

PATTERN EVIDENT DURING THE PRECEDING PERIOD CONTINUES AT NEARLY THE SAME 

STRENGTH INTO WEEK-2. HERE IT IS IMPORTANT TO DISCUSS SUBTLE, BUT IMPORTANT, 

MODEL DIFFERENCES WITH RESPECT TO BOTH COASTS FLANKING THE CONUS. THESE 

DIFFERENCES ARE THE SAME AS THOSE DISCUSSED IN THE 6-10 DAY PERIOD, BUT OF 

GREATER MAGNITUDE. THE ECMWF (EC) AND CANADIAN ENSEMBLE MEANS SUPPORT GREATER 

RIDGING DIRECTLY ALONG THE WEST COAST AND A DRAMATIC WEAKENING OF THE MEAN 

UPPER-LEVEL LOW IN THE GULF OF ALASKA FROM THE PRECEDING PERIOD. THE VARIOUS 

GEFS MEANS FROM THE PAST DAY, AS WELL AS THE HIGH-RESOLUTION GFS RUNS SUPPORT A 

VIGOROUS UPPER-LEVEL TROUGH IN THE GULF OF ALASKA WITH A MORE PROGRESSIVE RIDGE

POSITION MOVING TOWARD THE ROCKIES AND WESTERN PLAINS.  THE HYDROCLIMATE 

DIFFERENCES BETWEEN THIS SCENARIOS IS STARK, WITH THE FORMER SUPPORTING DRIER 

CONDITIONS ALONG THE WEST COAST AND A MORE ACTIVE STORM TRACK FROM THE SOUTHERN 

PLAINS TO THE EAST COAST.  THE LATTER WOULD SUGGEST MILDER TEMPERATURES MOVING 

TOWARD THE CENTRAL CONUS, WETTER CONDITIONS FOR PARTS OF THE WEST COAST, AND A 

STORM TRACK EVOLVING WELL EAST OF THE CONUS.

 

THE OFFICIAL 500-HPA HEIGHT MANUAL BLEND WEIGHTS THE GEFS SOLUTION SLIGHTLY 

MORE, ACCOUNTING FOR ITS SLIGHTLY BETTER SKILL AT THIS LEAD SO FAR THIS WINTER 

SEASON.  PURELY ANECDOTAL EVIDENCE FROM EARLIER THIS SEASON SUGGESTS THE GFS

HAS BEEN SOMEWHAT BETTER AT PREDICTING THE WEEK-2 PATTERN NEAR THE WEST COAST.  

HOWEVER, THE CANADIAN AND EC SPAGHETTI DIAGRAMS SHOW LESS SPREAD THAN THE 6Z 

GEFS ENSEMBLE IN THAT LOCATION.  IN ADDITION, BLOCKING PATTERNS INEVITABLY 

FORCE SLOW-MOVING, CUTOFF FEATURES WHICH ARE NOTORIOUSLY HARD TO PREDICT, 

ESPECIALLY AT THIS LEAD. THAT COMBINED WITH THE CHANGE OF SEASON MAKES FOR A 

RATHER UNCERTAIN OUTLOOK.

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Looks to me like the trough is centered just a bit too far east for the TN valley (per the Euro ens maps posted).  Perhaps someone in the Carolinas or Georgia could score with it, but we need it to back up a few hundred miles to give us a widespread winter storm.  Anything can happen though.

 

Are we really suppose to buy the cold vortex setting up that far south???  Looks out of place ...........so maybe its not so deep/far south and would allow something to pop or the trough to sharpen up with something diving into the base of it.

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Good write-ups from CPC, IMO…

 

 

6-10 DAY OUTLOOK FOR FEB 27 - MAR 03, 2013

 

TODAY'S ENSEMBLE MEAN SOLUTIONS REMAIN IN REASONABLY GOOD AGREEMENT ON THE 

500-HPA HEIGHT PATTERN OVER NORTH AMERICA, WITH SOME DIFFERENCES AMONG THE 

ECMWF(EC)/CANADIAN MEANS AND THE GFS ENSEMBLE (GEFS) MEAN. THE EC/CANADIAN 

ENSEMBLES SUPPORT A LARGER RIDGE FARTHER WEST ACROSS NORTH AMERICA, WHILE THE 

GFS ENSEMBLES ARE MORE PROGRESSIVE IN THE EASTERN PACIFIC RESULTING IN A MEAN 

RIDGE POSITION CLOSER TO THE ROCKIES. IN TODAY'S OFFICIAL 500-HPA HEIGHT BLEND, 

THE GEFS IS WEIGHTED SLIGHTLY MORE THAN THE OTHERS DUE TO BETTER OVERALL SKILL 

DURING THE LAST 60 DAYS. ADDITIONALLY, GOOD RUN-TO-RUN CONTINUITY AMONG 

OPERATIONAL RUNS PROMPTED A LARGER THAN AVERAGE WEIGHTING IN THE MANUAL BLEND

THE FORECAST CIRCULATION IS STILL DOMINATED BY A -NAO BLOCKING PATTERN OVER THE 

WESTERN ATLANTIC AND EASTERN NORTH AMERICA, CONSISTING OF AN EXPANSIVE AREA OF 

MUCH-ABOVE-NORMAL HEIGHTS FROM NEAR HUDSON BAY EASTWARD TO NORTHERN EUROPE, 

SOUTH OF WHICH THERE IS A ZONALLY-ORIENTED AREA OF BELOW NORMAL HEIGHTS FROM 

SOUTHEASTERN NORTH AMERICA TO SOUTHWESTERN EUROPE.

 

THE GREATEST PROBABILITY FOR BELOW-NORMAL TEMPERATURES IS FORECAST OVER THE 

SOUTHEASTERN QUADRANT OF THE CONUS. THIS AREA IS FORECAST TO EXPERIENCE 

ANOMALOUS NORTHERLY FLOW BOTH AT THE SURFACE AND ALOFT. MILDER-THAN-NORMAL 

TEMPERATURES CONTINUE TO BE FAVORED ACROSS MUCH OF THE NORTHERN TIER OF THE 

CONUS DUE TO WARM AIR ADVECTION ASSOCIATED WITH A MAJOR STORM SYSTEM EARLY IN 

THE PERIOD AND A LACK OF TYPICALLY-COLD AIR OVER THE CANADIAN SOURCE REGION TO 

THE NORTH. THE BLOCKING PATTERN OVER EASTERN NORTH AMERICA FAVORS A STORM TRACK 

NEAR OR JUST OFF THE EAST COAST AND DRIER-THAN-MEDIAN CONDITIONS ACROSS MUCH OF 

THE WEST-CENTRAL CONUS UNDER NORTHWESTERLY FLOW ALOFT.

 

 

8-14 DAY OUTLOOK FOR MAR 01 - 07 2013 

 

THE ENSEMBLE MEAN SOLUTIONS INDICATE THAT THE CIRCULATION PATTERN FOR WEEK-2 

WILL REMAIN VERY SIMILAR TO THAT FOR THE 6-10 DAY PERIOD, EXCEPT WITH SOME 

EVOLUTION OVER THE EASTERN PACIFIC AND FAR WESTERN NORTH AMERICA. THE BLOCKING 

PATTERN EVIDENT DURING THE PRECEDING PERIOD CONTINUES AT NEARLY THE SAME 

STRENGTH INTO WEEK-2. HERE IT IS IMPORTANT TO DISCUSS SUBTLE, BUT IMPORTANT, 

MODEL DIFFERENCES WITH RESPECT TO BOTH COASTS FLANKING THE CONUS. THESE 

DIFFERENCES ARE THE SAME AS THOSE DISCUSSED IN THE 6-10 DAY PERIOD, BUT OF 

GREATER MAGNITUDE. THE ECMWF (EC) AND CANADIAN ENSEMBLE MEANS SUPPORT GREATER 

RIDGING DIRECTLY ALONG THE WEST COAST AND A DRAMATIC WEAKENING OF THE MEAN 

UPPER-LEVEL LOW IN THE GULF OF ALASKA FROM THE PRECEDING PERIOD. THE VARIOUS 

GEFS MEANS FROM THE PAST DAY, AS WELL AS THE HIGH-RESOLUTION GFS RUNS SUPPORT A 

VIGOROUS UPPER-LEVEL TROUGH IN THE GULF OF ALASKA WITH A MORE PROGRESSIVE RIDGE

POSITION MOVING TOWARD THE ROCKIES AND WESTERN PLAINS.  THE HYDROCLIMATE 

DIFFERENCES BETWEEN THIS SCENARIOS IS STARK, WITH THE FORMER SUPPORTING DRIER 

CONDITIONS ALONG THE WEST COAST AND A MORE ACTIVE STORM TRACK FROM THE SOUTHERN 

PLAINS TO THE EAST COAST.  THE LATTER WOULD SUGGEST MILDER TEMPERATURES MOVING 

TOWARD THE CENTRAL CONUS, WETTER CONDITIONS FOR PARTS OF THE WEST COAST, AND A 

STORM TRACK EVOLVING WELL EAST OF THE CONUS.

 

THE OFFICIAL 500-HPA HEIGHT MANUAL BLEND WEIGHTS THE GEFS SOLUTION SLIGHTLY 

MORE, ACCOUNTING FOR ITS SLIGHTLY BETTER SKILL AT THIS LEAD SO FAR THIS WINTER 

SEASON.  PURELY ANECDOTAL EVIDENCE FROM EARLIER THIS SEASON SUGGESTS THE GFS

HAS BEEN SOMEWHAT BETTER AT PREDICTING THE WEEK-2 PATTERN NEAR THE WEST COAST.  

HOWEVER, THE CANADIAN AND EC SPAGHETTI DIAGRAMS SHOW LESS SPREAD THAN THE 6Z 

GEFS ENSEMBLE IN THAT LOCATION.  IN ADDITION, BLOCKING PATTERNS INEVITABLY 

FORCE SLOW-MOVING, CUTOFF FEATURES WHICH ARE NOTORIOUSLY HARD TO PREDICT, 

ESPECIALLY AT THIS LEAD. THAT COMBINED WITH THE CHANGE OF SEASON MAKES FOR A 

RATHER UNCERTAIN OUTLOOK.

 

 

Interesting.  Looks like we need to root for the west coast ridge axis more WEST as the EURO and Canadian show.  Isn't that ironic?  Usually it's too far west making a -PNA.  Noteworthy too if the EURO and Canadian is right, it would be a stormy look for the east coast, I assume no matter what the surface of the models at this range say.  Sad to say though the GFS has been good on long range patterns this year so the rockies ridge axis and thus cold and dry could come in to play.  

 

Seems like we need to keep an eye on that ridge axis.  West coast = cold/stormy, Rockies = cold/dry.  That's what I got from that anyway.  Good read.  

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12z Canadian Global for archiving sake since this likely the only time we will see a run like this.  Pure deep south snow clobber.  Sorry TN (except far east TN).

 

 This 12Z 2/21 run of the CMC fantasy would give on 3/2-3 verbatim ~8-10" of snow for many inland in MS/AL/GA/SC/NC with spots like Jackson. MS getting close to or a little over a foot! So, that would be a once per mulitdecade widespread, very heavy SE US type of snow. It wallops places like Montgomery, Birm, Columbus, Macon, Augusta, Atl.-Athens, Columbia, GSP, HKY, Asheville, Charlotte, and Raleigh. This run is about as good as that one Euro run from a few weeks ago but it gives areas a little further south the heaviest snow. Unfortunately, this is days 9-10. 

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 This 12Z 2/21 run of the CMC fantasy would give on 3/2-3 verbatim ~8-10" of snow for many inland in MS/AL/GA/SC/NC with spots like Jackson. MS getting close to or a little over a foot! So, that would be a once per mulitdecade widespread, very heavy SE US type of snow. It wallops places like Montgomery, Birm, Columbus, Macon, Augusta, Atl.-Athens, Columbia, GSP, HKY, Asheville, Charlotte, and Raleigh. This run is about as good as that one Euro run from a few weeks ago but it gives areas a little further south the heaviest snow. Unfortunately, this is days 9-10. 

I think this is the March 3-4 storm that keeps showing up on different models, lets hope so.  I would definitely say it was worth the wait all winter for this. 

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The question is.......cold and wet or cold and dry?

 

Week 1 (2/25-3/3): wet

Week 2 (3/4-3/10): slightly drier than normal northern SE to near normal southern SE

Weeks 3-4 (3/11-24): near normal

 

Week 1 turning quite cold

Week 2: very cold..coldest week

Week 3: still solid chill

Week 4: slightly below normal

 

Weeks 1-4: strong west based -NAO

 

AO for weeks 1-4: neutral, negative, negative, neutral

 

PNA: + for weeks 1-2; neutral weeks 3-4

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Week 1 (2/25-3/3): wet

Week 2 (3/4-3/10): slightly drier than normal northern SE to near normal southern SE

Weeks 3-4 (3/11-24): near normal

 

Week 1 turning quite cold

Week 2: very cold..coldest week

Week 3: still solid chill

Week 4: slightly below normal

 

Weeks 1-4: strong west based NAO

 

AO fro 1-4: neutral, negative, negative, neutral

 

PNA: + for weeks 1-2; neutral weeks 3-4

 

Good stuff, Larry!

 

I am a bit skeptical considering how off the weeklies have been at times this winter, but they do align with your analogs.

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