EasternUSWX Posted September 7, 2012 Share Posted September 7, 2012 Quite the disco ...DAMAGING SEVERE THUNDERSTORMS ARE EXPECTED ACROSS THE NORTHEASTERN U.S. SATURDAY... POTENTIALLY SIGNIFICANT DAMAGING WIND EVENT IS EXPECTED ACROSS MUCH OF THE NERN U.S. SATURDAY. LATEST MODEL GUIDANCE...ESPECIALLY THE NAM/ECMWF...SUGGEST SHORT-WAVE TROUGH OVER THE UPPER GREAT LAKES WILL DIG INTO LOWER MI BY 08/12 BEFORE EJECTING NEWD IN A NEGATIVELY TILTED FASHION AND DEEPENING OVER SERN ONTARIO/WRN QUEBEC. 90-120M 12HR HEIGHT FALLS WILL SPREAD ACROSS WRN/UPSTATE NY DURING THE DAY ENSURING A STRONGLY FORCED AND CONVECTIVELY-ACTIVE COLD FRONT. THIS EVOLUTION SUGGESTS A FRONTAL INTRUSION THAT WILL INDUCE A BAND OF SEVERE THUNDERSTORMS AS IT SURGES ACROSS THE NRN MIDDLE ATLANTIC REGION INTO NEW ENGLAND. ALL INDICATIONS FAVOR A SQUALL ALONG THE WIND SHIFT AT SUNRISE FROM SRN ONTARIO SWD ACROSS OH...TRAILING INTO THE TN VALLEY. THIS ACTIVITY IS EXPECTED TO INTENSIFY AS IT MOVES INTO WRN NY/PA...ESPECIALLY BY 18Z AS BOUNDARY LAYER BEGINS TO WARM. ALTHOUGH FORECAST LAPSE RATES ARE NOT PARTICULARLY STEEP BOUNDARY LAYER AIRMASS IS FAIRLY MOIST ATTM WITH UPPER 60S-70F SFC DEW POINTS IN PLACE ACROSS THE MIDDLE ATLANTIC REGION. THERE IS LITTLE REASON TO BELIEVE THIS AIRMASS WILL NOT SPREAD NWD ACROSS PA/NJ INTO UPSTATE NY AHEAD OF THE COLD FRONT AND AMPLE MOISTURE/INSTABILITY WILL SPREAD NWD TOWARD THE CANADIAN BORDER TO SUPPORT ROBUST UPDRAFTS WITHIN A STRONGLY SHEARED ENVIRONMENT. OF PARTICULAR CONCERN IS THE EXPECTED MID LEVEL JET THAT SHOULD INTENSIFY AS IT EJECTS ACROSS WRN PA TO SPEEDS IN EXCESS OF 70KT OVER UPSTATE NY BY 09/00Z. WITH DEEPENING SFC LOW OVER SERN ONTARIO FORECAST SHEAR PROFILES BECOME QUITE FAVORABLE FOR SUSTAINING ORGANIZED UPDRAFTS. WHILE A DAMAGING SQUALL LINE IS EXPECTED ALONG THE ADVANCING COLD FRONT...ENVIRONMENTAL SHEAR WILL BECOME QUITE FAVORABLE FOR PRE-FRONTAL SUPERCELLS AND EMBEDDED SUPERCELLS WITHIN THE MAIN SQUALL LINE. FORECAST SOUNDINGS FROM NRN NJ NWD THROUGH THE HUDSON VALLEY SUGGEST TORNADOES ARE POSSIBLE IF DISCRETE SUPERCELLS CAN EVOLVE AHEAD OF THE MAIN LINE AND WITH CIRCULATIONS WITHIN THE LINE. LATEST MODEL GUIDANCE SUGGESTS THE BACK EDGE OF THE PRIMARY SQUALL LINE WILL ADVANCE INTO THE HUDSON VALLEY BY LATE AFTERNOON TRAILING SWWD INTO CNTRL VA BY 09/00Z WITH SUBSEQUENT MOVEMENT ACROSS MUCH OF NEW ENGLAND BY 06Z. Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 I'm just outside it I'd actually sorta expect it to come south Link to comment Share on other sites More sharing options...
mappy Posted September 7, 2012 Share Posted September 7, 2012 I'd actually sorta expect it to come south I just saw your tweet saying the same... Good stuff Link to comment Share on other sites More sharing options...
Kmlwx Posted September 7, 2012 Author Share Posted September 7, 2012 I'd actually sorta expect it to come south Reasoning? I don't doubt it at all given some of the modeling but just curious as to your thoughts. Link to comment Share on other sites More sharing options...
mappy Posted September 7, 2012 Share Posted September 7, 2012 Reasoning? I don't doubt it at all given some of the modeling but just curious as to your thoughts. Bc he has an orange tag, therefore he knows all. Shush Link to comment Share on other sites More sharing options...
Kmlwx Posted September 7, 2012 Author Share Posted September 7, 2012 Bc he has an orange tag, therefore he knows all. Shush He's an Adminicaster Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 Reasoning? I don't doubt it at all given some of the modeling but just curious as to your thoughts. It's more marginal down purely based on the trough movement here tho I think better instability might help even it out. I'm not sure why they removed us from the hatching other than the fact that only the 45% area is hatched now so maybe it doesn't mean anything. It's a sick setup though... particularly a bit north. Link to comment Share on other sites More sharing options...
Kmlwx Posted September 7, 2012 Author Share Posted September 7, 2012 It's more marginal down purely based on the trough movement here tho I think better instability might help even it out. I'm not sure why they removed us from the hatching other than the fact that only the 45% area is hatched now so maybe it doesn't mean anything. It's a sick setup though... particularly a bit north. I'm excited. Tho I should have let you start the thread Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 Tho actually with the backend vort we still sorta end up in a good zone at the base of the trough. I'm a little sketched about their eastern extent.. I'm not sure I buy much discrete activity that far east particularly and the main line should be pretty late for W NE etc. Link to comment Share on other sites More sharing options...
H2O Posted September 7, 2012 Share Posted September 7, 2012 NCEP's WRFs are in. Much less messy out in front of the line than the NAM is. Not derechoish enough Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 NAM 4K WRF is pretty fast ... line thru here mid-afternoon. http://www.weatherbellmodels.com/weather/hires/2012090712/east/hires_ref_east_mouse.php Link to comment Share on other sites More sharing options...
H2O Posted September 7, 2012 Share Posted September 7, 2012 NAM 4K WRF is pretty fast ... line thru here mid-afternoon. http://www.weatherbe..._east_mouse.php Very interesting to see it blow up real quick as it gets just east of the apps Link to comment Share on other sites More sharing options...
MN Transplant Posted September 7, 2012 Share Posted September 7, 2012 NAM 4K WRF is pretty fast ... line thru here mid-afternoon. http://www.weatherbe..._east_mouse.php 5pm or so for the front on the Euro. Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 5pm or so for the front on the Euro. The Euro and GFS are a bit fast for my liking.. at least in kicking the sfc low pretty far north. Given how quickly it deepens and how strong it is not sure how much it matters. I don't particularly expect a major tornado threat anyway and that's maybe the main difference there. Such a dynamic scenario might have to wait till morning to really get a solid idea. Link to comment Share on other sites More sharing options...
Ellinwood Posted September 7, 2012 Share Posted September 7, 2012 Wow @ the 12z NAM... upper PA/south-central NY could be hurtin tomorrow if that verifies. GFS and NAM are in two different camps WRT the low-level winds and the surface low progression... it will be interesting to see which verifies. I'd lean a little towards the GFS for the low-level winds, but since this has particularly-strong dynamics I'm not so confident in that right now. The surface winds will also be critical in boosting CAPE (NAM = SE winds, better low-level moisture and higher CAPE, GFS = SW winds, more downsloping and drier low-level air causing lower CAPE). Link to comment Share on other sites More sharing options...
BTRWx Posted September 7, 2012 Share Posted September 7, 2012 Not derechoish enough There is no 100 degree heat to deal with. Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 I just want a good shelf cloud. And an EF-2 hitting the Capitol. Link to comment Share on other sites More sharing options...
mattie g Posted September 7, 2012 Share Posted September 7, 2012 I just want a good shelf cloud. And an EF-2 hitting the Capitol. The FBI should be at your workplace soon. Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 The FBI should be at your workplace soon. Beware of my weather machine! I think it could take an EF2 OK. Maybe I'll scale back to a 1. Link to comment Share on other sites More sharing options...
Disc Posted September 7, 2012 Share Posted September 7, 2012 Be sure to get some good video, Ian. Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 Be sure to get some good video, Ian. Epic DC split likely Link to comment Share on other sites More sharing options...
EastCoast NPZ Posted September 7, 2012 Share Posted September 7, 2012 I'll take my sprinkles and kiss this ****ing heatwave goodbye. Link to comment Share on other sites More sharing options...
yoda Posted September 7, 2012 Share Posted September 7, 2012 LWX afternoon AFD mentions main threat to be damaging winds... but there is risk for tornados tomorrow as well Link to comment Share on other sites More sharing options...
MN Transplant Posted September 7, 2012 Share Posted September 7, 2012 NAM 4K WRF is pretty fast ... line thru here mid-afternoon. http://www.weatherbe..._east_mouse.php 18z NAM now in line with the rest Summer time of death - 5pm 9/8/12 Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 18z NAM now in line with the rest Summer time of death - 5pm 9/8/12 I agree with the mod risk tho I'm still sorta perplexed with the shape of it. I'd have brought it at least to DC and maybe a bit south and not included New England. There is the risk up there that the line won't start to weaken quick enough but I don't see much model support for it at least, whereas most guidance has a pretty fat squall coming thru here with plenty of wind to tap. Link to comment Share on other sites More sharing options...
Kmlwx Posted September 7, 2012 Author Share Posted September 7, 2012 I agree with the mod risk tho I'm still sorta perplexed with the shape of it. I'd have brought it at least to DC and maybe a bit south and not included New England. There is the risk up there that the line won't start to weaken quick enough but I don't see much model support for it at least, whereas most guidance has a pretty fat squall coming thru here with plenty of wind to tap. I'm sure with a future update we'll see it pulled south. You tend to be good at predicting the SPC actions lol Link to comment Share on other sites More sharing options...
Ian Posted September 7, 2012 Share Posted September 7, 2012 I'm sure with a future update we'll see it pulled south. You tend to be good at predicting the SPC actions lol First day 1 will have us in 15% wind now. Link to comment Share on other sites More sharing options...
yoda Posted September 7, 2012 Share Posted September 7, 2012 I forsee mod risk coming down to N VA tomorrow... 45 wind 15 hail 5 tor Link to comment Share on other sites More sharing options...
Kmlwx Posted September 7, 2012 Author Share Posted September 7, 2012 I forsee mod risk coming down to N VA tomorrow... 45 wind 15 hail 5 tor The evolution of weather weenies - 1) Forecast weather 2) Forecast the forecast of the weather 3) Forecast the model run forecast used by forecasters to create a forecast Link to comment Share on other sites More sharing options...
yoda Posted September 7, 2012 Share Posted September 7, 2012 The evolution of weather weenies - 1) Forecast weather 2) Forecast the forecast of the weather 3) Forecast the model run forecast used by forecasters to create a forecast The Force is strong with this one this should also be our last big severe weather threat of the year IMO Link to comment Share on other sites More sharing options...
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