NaoPos Posted January 27, 2013 Share Posted January 27, 2013 Lakes cutter bringing the heat! discuss ACUS48 KWNS 270930 SPC AC 270930 DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0330 AM CST SUN JAN 27 2013 VALID 301200Z - 041200Z ...DISCUSSION... THERE IS REASONABLE AGREEMENT AMONGST THE LATEST SUITE OF GUIDANCE THAT A POWERFUL AND HIGHLY AMPLIFIED UPPER TROUGH WILL MAKE RAPID PROGRESS TOWARD THE ERN SEABOARD THROUGH LATE D4/WEDNESDAY. A MID LEVEL WIND MAX IN EXCESS OF 100KT IS FORECAST TO ROTATE THROUGH THE BASE OF THE TROUGH FROM THE TN VALLEY TO THE MID ATLANTIC COINCIDENT WITH THE ADVANCING COLD FRONT ACROSS THESE AREAS. MODELS ALSO SUGGEST THAT LOW AND DEEP-LAYER MOISTURE WILL INCREASE RAPIDLY IMMEDIATELY AHEAD OF THE FRONTAL ZONE WITH ECMWF DEPICTING A PLUME OF AT LEAST 1.5 INCH PW VALUES EXTENDING AS FAR NORTH AS PHL AREA BY WEDNESDAY EVENING. QPF AND VERTICAL MOTION FIELDS FROM LATEST EC AND GFS MODELS SUGGEST A CONTINUATION AND/OR RESURGENCE OF CONVECTION ALONG NEARLY THE ENTIRE FRONT AMIDST INTENSE CLOUD-BEARING SHEAR. WHILE CAPE ACROSS MUCH OF THE RISK AREA WILL REMAIN LOW...EXPECT BOUNDARY LAYER WARMING/MOISTENING TO BECOME SUFFICIENT ENOUGH TO SUPPORT THE DOWNWARD TRANSPORT OF HIGH MOMENTUM AIR TO THE SURFACE WITH DAMAGING WINDS EXPECTED TO ACCOMPANY THE PASSAGE OF THE CONVECTIVE LINE. THE STRONG COLD FRONT SHOULD BE CLEAR OF ALL BUT FAR SRN FL BY D5/THURSDAY. COLD AND DRY AIR IN THE WAKE OF THIS SYSTEM APPEARS TO SHUT DOWN FURTHER PROSPECTS FOR STRONG TO SEVERE TSTMS AT LEAST THROUGH THE REMAINDER OF THE WEEK. ..CARBIN.. 01/27/2013 Here's some soundings from KPHL with the frontal passage. This $hit means business. Link to comment Share on other sites More sharing options...
NaoPos Posted January 27, 2013 Author Share Posted January 27, 2013 GFS forecasting a 50-75kt 950mb LLJ in the vicinity with heavy rain. Downward momentum looks quite plauible. COuld be a severe squall line type set up. Link to comment Share on other sites More sharing options...
phlwx Posted January 27, 2013 Share Posted January 27, 2013 Thunderless squall. Link to comment Share on other sites More sharing options...
Rainshadow Posted January 27, 2013 Share Posted January 27, 2013 GFS not backing down yet, 107mph 850mb winds forecast for Philadelphia. Someone better start building the inversion now. Link to comment Share on other sites More sharing options...
Mitchell Gaines Posted January 28, 2013 Share Posted January 28, 2013 Thunderless squall. Simialr events back in KY produce tornadoes and tornado warnings with no lightning . Link to comment Share on other sites More sharing options...
Mitchell Gaines Posted January 28, 2013 Share Posted January 28, 2013 Put in the long term AFD a few days ago a few hundered J/KG CAPE and we're in business. Still doesn't look likely. Gusty winds a very good bet though. Very impressive LLJ. Link to comment Share on other sites More sharing options...
Quakertown needs snow Posted January 28, 2013 Share Posted January 28, 2013 so how fast will the temps drop? is flash freeze possible? back end flurries/snow showers? Link to comment Share on other sites More sharing options...
noctilucent Posted January 28, 2013 Share Posted January 28, 2013 You know what kind of winter it is when, you're in a severe risk zone in January! I remember something like this in 91 or 92, maybe.... Link to comment Share on other sites More sharing options...
tombo82685 Posted January 28, 2013 Share Posted January 28, 2013 so how fast will the temps drop? is flash freeze possible? back end flurries/snow showers? doesn't look like flash freeze anywhere outside the pocs. Might be some rain/snow showers on thurs. Link to comment Share on other sites More sharing options...
Violentweatherfan Posted January 28, 2013 Share Posted January 28, 2013 doesn't look like flash freeze anywhere outside the pocs. Might be some rain/snow showers on thurs. Even if there was a possibility, wouldn't the winds just "blow dry" everything? With the exception of puddles freezing, standing water flash freeze isn't cause for much alarm...right? Link to comment Share on other sites More sharing options...
tombo82685 Posted January 28, 2013 Share Posted January 28, 2013 Even if there was a possibility, wouldn't the winds just "blow dry" everything? With the exception of puddles freezing, standing water flash freeze isn't cause for much alarm...right? Pretty much Link to comment Share on other sites More sharing options...
phlwx Posted January 28, 2013 Share Posted January 28, 2013 You know what kind of winter it is when, you're in a severe risk zone in January! I remember something like this in 91 or 92, maybe.... Jan 06, I believe, had severe warnings in South Jersey. Link to comment Share on other sites More sharing options...
NaoPos Posted January 28, 2013 Author Share Posted January 28, 2013 Jan 06, I believe, had severe warnings in South Jersey. I know there was a severe warned squall line in the winter within the last 3 years.... Link to comment Share on other sites More sharing options...
tombo82685 Posted January 29, 2013 Share Posted January 29, 2013 The 18z gfs is ridiculous with the llj. It has 94 mph winds at 925mb, that's pretty nuts. Any convection that is elevated enough has the ability to bring that down. Link to comment Share on other sites More sharing options...
Absolute Humidity Posted January 29, 2013 Share Posted January 29, 2013 Well, at least we don't have to worry about the leaves being on the trees Link to comment Share on other sites More sharing options...
Rainshadow Posted January 29, 2013 Share Posted January 29, 2013 You know what kind of winter it is when, you're in a severe risk zone in January! I remember something like this in 91 or 92, maybe.... There was an event when I was still in NYC in one of those Januaries, where a tornado watch was issued and some schools decided to early dismiss as the squall line was moving through. Sometimes it is good to be lucky. Link to comment Share on other sites More sharing options...
phlwx Posted January 29, 2013 Share Posted January 29, 2013 0z GFS at 900 mb has 80 mph winds. Fun times. Link to comment Share on other sites More sharing options...
tmagan Posted January 29, 2013 Share Posted January 29, 2013 There was an event when I was still in NYC in one of those Januaries, where a tornado watch was issued and some schools decided to early dismiss as the squall line was moving through. Sometimes it is good to be lucky. The week before the Thanksgiving snowstorm in 1989, there was a tornado near a Poughkeepsie school that killed 7 students. http://www.recordonline.com/apps/pbcs.dll/article?AID=/99999999/NEWS/70920020 Link to comment Share on other sites More sharing options...
Quakertown needs snow Posted January 29, 2013 Share Posted January 29, 2013 GFS brings the downpour! Link to comment Share on other sites More sharing options...
NaoPos Posted January 29, 2013 Author Share Posted January 29, 2013 would there technically be an inversion layer here? Link to comment Share on other sites More sharing options...
NaoPos Posted January 29, 2013 Author Share Posted January 29, 2013 http://www.meteo.psu.edu/~fxg1/NAMSFC4_12z/temp33.gif 60's tomorrow? (stolen off earthlight in NYC forum) http://www.meteo.psu.edu/~fxg1/NAMSFC4_12z/temp33.gif Link to comment Share on other sites More sharing options...
Quakertown needs snow Posted January 29, 2013 Share Posted January 29, 2013 torch / rain up through Maine. Good bye nice skiing snow Link to comment Share on other sites More sharing options...
HM Posted January 29, 2013 Share Posted January 29, 2013 In a situation like tomorrow, we are going to be battling an increasing SE flow up until FROPA and extremely strong deep layer shear. Basically, we are going to need all forces aligned from the lowest level boundary to the mid levels working together to lift parcels in an environment that wants to rip convection apart (too much wind shear and stability flux). If we get all forcing timed nicely (vertically) then scattered to widespread wind gusts exceeding 50 MPH will be common during squall. If different forces begin to fall off the mark, as far as alignment, then it most likely will be a typical run-of-the-mill squall (30-50 mph winds). The deepest moisture will most likely stay in W-C MD / VA / far S-C PA but it could possibly flux into the Delaware Valley (>=15°C dews will try to push in but will struggle against SE flow, so a lot of us, esp. east, will fail to reach 15°C). My worry is that a slower FROPA will mean deeper SE flow for a longer time, causing even more stability to be fluxed in and holding a more stout inversion. But even then, an alignment of VVs / front would be able to overcome this to some extent. Link to comment Share on other sites More sharing options...
chubbs Posted January 29, 2013 Share Posted January 29, 2013 SPC has pushed the slight risk area further NE. Boundary now Baltimore/Dover/Cape May Link to comment Share on other sites More sharing options...
am19psu Posted January 29, 2013 Share Posted January 29, 2013 Mt. Holly briefing package: http://t.co/WuhU8Rz7 Link to comment Share on other sites More sharing options...
famartin Posted January 29, 2013 Share Posted January 29, 2013 would there technically be an inversion layer here? yes Link to comment Share on other sites More sharing options...
NaoPos Posted January 29, 2013 Author Share Posted January 29, 2013 watch out Jersey shore: 18Z NAM KEEPS the heaviest precip to our west. Link to comment Share on other sites More sharing options...
Absolute Humidity Posted January 30, 2013 Share Posted January 30, 2013 watch out Jersey shore: 18Z NAM KEEPS the heaviest precip to our west. Wow, 90kts around 900mb that's nuts. I'm surprised this thread is so quiet. Link to comment Share on other sites More sharing options...
famartin Posted January 30, 2013 Share Posted January 30, 2013 Wow, 90kts around 900mb that's nuts. I'm surprised this thread is so quiet. Strong inversion may keep best winds from reaching the surface. Link to comment Share on other sites More sharing options...
Absolute Humidity Posted January 30, 2013 Share Posted January 30, 2013 Strong inversion may keep best winds from reaching the surface. I sure hope so. My generator is still tired from sandy. Link to comment Share on other sites More sharing options...
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