thunderman Posted November 30, 2014 Share Posted November 30, 2014 Looks like it could be a solid thump of zr/pl for some well west of the cities. Link to comment Share on other sites More sharing options...
Bob Chill Posted November 30, 2014 Share Posted November 30, 2014 Yeah. Xbox would imply a little snow to start maybe for places N&W of 95. Maybe even 1" of accumulation? It's really tight in the midlevels for snow. The ptype maps don't really jibe with the 850 panels. Winwxlvr looks to be in one of the better spots for a combo of ok temps and precip. Further north has better temps but not good on the qpf during the window. I'm hugging tomorrow nights hrrr. It did really well with the last event Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted December 1, 2014 Share Posted December 1, 2014 It's really tight in the midlevels for snow. The ptype maps don't really jibe with the 850 panels. Winwxlvr looks to be in one of the better spots for a combo of ok temps and precip. Further north has better temps but not good on the qpf during the window. I'm hugging tomorrow nights hrrr. It did really well with the last event The closest sounding I can get close to me would imply snow not likely. That was the GFS I looked at. Link to comment Share on other sites More sharing options...
yoda Posted December 1, 2014 Share Posted December 1, 2014 21z SREFs have 0.5" QPF from DCA and southwestward from 00z TUE to 00z WED Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted December 1, 2014 Share Posted December 1, 2014 21z SREFs have 0.5" QPF from DCA and southwestward from 00z TUE to 00z WEDIf they are to be believed, 0.25" or so out here with temps below freezing, 850's under (close though)....would be a morning mess.Edit: that's through 18z Tues Link to comment Share on other sites More sharing options...
yoda Posted December 1, 2014 Share Posted December 1, 2014 Looks like some snow out towards MRB on hr 33 per 00z NAM Link to comment Share on other sites More sharing options...
yoda Posted December 1, 2014 Share Posted December 1, 2014 Soundings barely support SN at DCA hr 36 ETA: more of a sleet sounding... but if rates good enough maybe snow instead? Link to comment Share on other sites More sharing options...
clskinsfan Posted December 1, 2014 Share Posted December 1, 2014 The NAM is actually a decent hit in NOVA. But surface temps are an issue again. I dont see how its as warm as it is with that HP. Link to comment Share on other sites More sharing options...
yoda Posted December 1, 2014 Share Posted December 1, 2014 00z NAM Raleigh snow maps show 2 to 3 inches of snow across N VA and DC... makes some sense since the 850 0c line is right in the area when the heaviest QPF comes in between 09z and 15z Tues morning... though I wonder if that is sleet accumulation based off of further evaluation of the soundings Link to comment Share on other sites More sharing options...
usedtobe Posted December 1, 2014 Share Posted December 1, 2014 Soundings barely support SN at DCA hr 36 ETA: more of a sleet sounding... but if rates good enough maybe snow instead? The sounding for DCA, IAD and JYO support sleet at 36 hours, not snow, there is a warm layer above 850 mb, FDK could be either sleet or snow as the temp in the warm layer is above freezing but about .8C. Link to comment Share on other sites More sharing options...
yoda Posted December 1, 2014 Share Posted December 1, 2014 The sounding for DCA, IAD and JYO support sleet at 36 hours, not snow, there is a warm layer above 850 mb, FDK could be either sleet or snow as the temp in the warm layer is above freezing but about .8C. Thanks Wes, had to go back and edit my post. Looks like a sleet storm Tuesday morning, how fun Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted December 1, 2014 Share Posted December 1, 2014 It looks close on type out here. Two questions...what causes a warm layer at basically only one specific level and how deep is that layer? Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted December 1, 2014 Share Posted December 1, 2014 Soundings barely support SN at DCA hr 36 ETA: more of a sleet sounding... but if rates good enough maybe snow instead? I know in the Dec storm of 2012, the Chill Storm, whenever we got heavy rates we got heavy snow. When it slacked it was mixed with sleet. Link to comment Share on other sites More sharing options...
usedtobe Posted December 1, 2014 Share Posted December 1, 2014 It looks close on type out here. Two questions...what causes a warm layer at basically only one specific level and how deep is that layer? It's not that deep of a layer, MRB still was a sleet sounding at 12z so I assume your sounding would be similar. Warm layers don't need to be too deep. In this case it develops because the really cold air is coming in at the surface due to damming and is being overrun by warmer southwesterly winds aloft. Our problem in this case is that we are not in the deep cold air. Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted December 1, 2014 Share Posted December 1, 2014 It's not that deep of a layer, MRB still was a sleet sounding at 12z so I assume your sounding would be similar. Warm layers don't need to be too deep. In this case it develops because the really cold air is coming in at the surface due to damming and is being overrun by warmer southwesterly winds aloft. Our problem in this case is that we are not in the deep cold air. Thanks Wes. Reason I ask is, my sounding is below at 750 and 850, but above at 800. I was wondering what the distance between them in feet was on average. My guess is about 3000-3500 feet? Link to comment Share on other sites More sharing options...
hosj III Posted December 1, 2014 Share Posted December 1, 2014 RGEM is weird looking. Sleet over DC with snow to the north and south. Roughly 3-5" of snow north of the city on clown maps. .5-1" of sleet in the city and parallel to it. If it's right the AM commute would be a disaster. Link to comment Share on other sites More sharing options...
Interstate Posted December 1, 2014 Share Posted December 1, 2014 When do you make this event it own thread? Link to comment Share on other sites More sharing options...
yoda Posted December 1, 2014 Share Posted December 1, 2014 00z GFS much faster bringing in precip to the LWX CWA by 11pm... 00z NAM was slower by about 6-8 hrs Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted December 1, 2014 Share Posted December 1, 2014 When do you make this event it own thread? As soon as you want to end the threat. Link to comment Share on other sites More sharing options...
aldie 22 Posted December 1, 2014 Share Posted December 1, 2014 It's pretty much a non issue driving on sleet Link to comment Share on other sites More sharing options...
yoda Posted December 1, 2014 Share Posted December 1, 2014 It's pretty much a non issue driving on sleet Really? I always thought it made driving harder Link to comment Share on other sites More sharing options...
aldie 22 Posted December 1, 2014 Share Posted December 1, 2014 Really? I always thought it made driving harder I don't know...maybe but around here just the threat just caused traffic to slow and two accidents NAM is about .45 of sleet at jyo...that would cover the ground nicely Link to comment Share on other sites More sharing options...
BTRWx Posted December 1, 2014 Share Posted December 1, 2014 GFS clearly shows a warming surface trend for Tuesday morning. I don't see much frozen for the cities. Link to comment Share on other sites More sharing options...
Deck Pic Posted December 1, 2014 Share Posted December 1, 2014 GFS clearly shows a warming surface trend for Tuesday morning. I don't see much frozen for the cities. I think because the lower levels are so cold, it is probably sleet even with 850 mb temps above zero...perhaps a met can confirm, but I would guess this is sleet....this is DC at 36 hours...surface is probably 34, so there will be no real impact unless it is heavy.... Link to comment Share on other sites More sharing options...
Deck Pic Posted December 1, 2014 Share Posted December 1, 2014 0z Canadian is a tad warmer than the GFS Is my guess, but it is wetter....I would't want to have to make a forecast for the usual spots...DC forecast is easier I think....rain to sleet to rain, temps falling into the low to mid 30s...little or no accumulation... Link to comment Share on other sites More sharing options...
Deck Pic Posted December 1, 2014 Share Posted December 1, 2014 Here is my facebook forecast for DC I wouldn't want to have to make a forecast for the far north and west burbs but for DC It is a bit easier, though by no means set in stone. Rain starts tomorrow evening, and temps slowly drop overnight. We mix with and change to sleet early morning on Tuesday, and temps fall into the low to mid 30s, but likely stay just above freezing. Later as temps rise we change back over to all rain. I don't expect any accumulation, especially on the street. Maybe a coating on car tops. It should become clearer by tomorrow evening. Doesn't look like a big deal for DC. Link to comment Share on other sites More sharing options...
EasternUSWX Posted December 1, 2014 Share Posted December 1, 2014 RGEM is a pretty significant sleetfest. Link to comment Share on other sites More sharing options...
Ellinwood Posted December 1, 2014 Share Posted December 1, 2014 I think because the lower levels are so cold, it is probably sleet even with 850 mb temps above zero...perhaps a met can confirm, but I would guess this is sleet....this is DC at 36 hours...surface is probably 34, so there will be no real impact unless it is heavy.... That there be a sleet sounding. Maybe a few deformed flakes that didn't quite melt mixing in as well... melting layer isn't impressively strong in that particular example. Link to comment Share on other sites More sharing options...
aldie 22 Posted December 1, 2014 Share Posted December 1, 2014 I'll take the 0z RGEM please http://www.americanwx.com/bb/uploads/monthly_12_2014/post-1352-0-15608900-1417408896.jpg Link to comment Share on other sites More sharing options...
mitchnick Posted December 1, 2014 Share Posted December 1, 2014 I'll take the 0z RGEM please http://www.americanwx.com/bb/uploads/monthly_12_2014/post-1352-0-15608900-1417408896.jpg 6Z run is not as good Link to comment Share on other sites More sharing options...
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