snow. Posted December 4, 2013 Share Posted December 4, 2013 The annoying thing at this range is that we cannot tell how much QPF we kill on IP on the ECMWF. Clearly, 1000-500 thickness is around 546 and 850mb temps are <=0°C, but raw soundings would be nice! based on GFS soundings, I think we probably go to sleet around the time 850's drop to -1. So I think for me 2-4 hours after onset..before the heavy stuff comes in. I think there will be a snow window even for DC proper. But perhaps as little as a 1/2" depending on timing. Link to comment Share on other sites More sharing options...
HM Posted December 4, 2013 Share Posted December 4, 2013 I know Ji got some heat earlier for saying this, but around here, 31/32 won't cut it for a decent ice storm, especially if the preceding days weren't frigid. Pretty obvious point you guys are making, even with the sarcasm of Ji, and it shouldn't be criticized. Besides what you guys already said, you also have latent heat release during ZR. If you are near 32, LH will help end things a lot faster. Link to comment Share on other sites More sharing options...
snow. Posted December 4, 2013 Share Posted December 4, 2013 precip is all pretty light thru 18z at least per the hi res across the area.. ~0.1" . yes...that is what I am seeing too.... Link to comment Share on other sites More sharing options...
snow. Posted December 4, 2013 Share Posted December 4, 2013 I know Ji got some heat earlier for saying this, but around here, 31/32 won't cut it for a decent ice storm, especially if the preceding days weren't frigid. we are going to be in the upper 20s dude for a decent portion...probably even me and you Link to comment Share on other sites More sharing options...
HM Posted December 4, 2013 Share Posted December 4, 2013 based on GFS soundings, I think we probably go to sleet around the time 850's drop to -1. So I think for me 2-4 hours after onset..before the heavy stuff comes in. I think there will be a snow window even for DC proper. But perhaps as little as a 1/2" depending on timing. What I find interesting on the ECMWF and GFS is the mid-level moistening and frontogenesis that comes through in the morning. While the models do not put out much if any QPF then, we certainly are making snow aloft. Does anyone have bufkit/etc. to see if there is decent omega in the snow growth zone early Sunday? Link to comment Share on other sites More sharing options...
snow. Posted December 4, 2013 Share Posted December 4, 2013 I don't think anyone east of a line from westminster to jyo has much to worry about ice wise. Maybe a pretty glaze for a time but hardly anything bendy. jmho disagree...I wouldn't be surprised by 25-27 for an extended period of time in those locations with a nice snow/sleet base. Link to comment Share on other sites More sharing options...
Ian Posted December 4, 2013 Share Posted December 4, 2013 we are going to be in the upper 20s dude for a decent portion...probably even me and you that's optimistic. none of the models get us below 30 even prior to the precip. you assuming the air mass is not being shown correctly? Link to comment Share on other sites More sharing options...
Bob Chill Posted December 4, 2013 Share Posted December 4, 2013 disagree...I wouldn't be surprised by 25-27 for an extended period of time in those locations with a nice snow/sleet base. I hope you're right. I'm just going off of anecdotal memory. More often than not the window of zr is usually shorter than we think. In this case it could be shorter because the window of sn-ip is longer....lol Link to comment Share on other sites More sharing options...
Ji Posted December 4, 2013 Share Posted December 4, 2013 its not a bad run but not as good as 00z(less snow) Link to comment Share on other sites More sharing options...
snow. Posted December 4, 2013 Share Posted December 4, 2013 I hope you're right. I'm just going off of anecdotal memory. More often than not the window of zr is usually shorter than we think. In this case it could be shorter because the window of sn-ip is longer....lol on the GFS OKV is 24-25 degrees at 1pm Link to comment Share on other sites More sharing options...
mitchnick Posted December 4, 2013 Share Posted December 4, 2013 its not a bad run but not as good as 00z(less snow) somebody earlier said snow maps were 3-4" across DCA/BWI....was that an old map from 0Z he mistakenly mentioned? Link to comment Share on other sites More sharing options...
Bob Chill Posted December 4, 2013 Share Posted December 4, 2013 its not a bad run but not as good as 00z(less snow) It all comes down to the initial wave. I would hardly be shocked if it came in juicier. So far the euro is the lightest solution overall with the front wave. At least we get to watch travel from the se to our door rather than wait for it to magically form nearby. The best part of overrunning imo. Link to comment Share on other sites More sharing options...
snow. Posted December 4, 2013 Share Posted December 4, 2013 that's optimistic. none of the models get us below 30 even prior to the precip. you assuming the air mass is not being shown correctly? Euro doesn't but GFS has me and you at 27-28 for a portion of the day Link to comment Share on other sites More sharing options...
stormtracker Posted December 4, 2013 Author Share Posted December 4, 2013 we are going to be in the upper 20s dude for a decent portion...probably even me and you I'm not seeing that? Link to comment Share on other sites More sharing options...
snow. Posted December 4, 2013 Share Posted December 4, 2013 somebody earlier said snow maps were 3-4" across DCA/BWI....was that an old map from 0Z he mistakenly mentioned? 12map I've seen has a narrow stripe of 2" for me and you, dropping of drmatically to the east Link to comment Share on other sites More sharing options...
Ian Posted December 4, 2013 Share Posted December 4, 2013 Euro doesn't but GFS has me and you at 27 during the day hmm yeah I guess it does. eh. dews are low.. but it's still tough to get a daytime below freezing this early even with precip. Link to comment Share on other sites More sharing options...
mitchnick Posted December 4, 2013 Share Posted December 4, 2013 12map I've seen has a narrow stripe of 2" for me and you, dropping of drmatically to the east thanks; I just checked Wunderground map and we'd definitely be in the 2"+ category Link to comment Share on other sites More sharing options...
snow. Posted December 4, 2013 Share Posted December 4, 2013 I'm not seeing that? DCA - 12z GFS...obviously it is kind of silly to parse these things at this range, but it is even colder to the west...I haven't seen any model that keeps IAD/JYO at 30+ the whole event...in fact much colder Link to comment Share on other sites More sharing options...
gymengineer Posted December 4, 2013 Share Posted December 4, 2013 I hope you're right. I'm just going off of anecdotal memory. More often than not the window of zr is usually shorter than we think. In this case it could be shorter because the window of sn-ip is longer....lol That's been the case the past three winters, but not in our slightly more distant past. The late January '09 mess held on more or less as expected with a nice glaze. Super Tuesday '08 was the same story with the late evening upgrade to Ice Storm Warnings when it became clear we weren't spiking to 50 degrees overnight. Of course, if you go further back to 1/99 and Jan through Feb 94 you have multiple more examples of prolonged periods of ZR-- but those were the ice storm winters. Link to comment Share on other sites More sharing options...
snow. Posted December 4, 2013 Share Posted December 4, 2013 hmm yeah I guess it does. eh. dews are low.. but it's still tough to get a daytime below freezing this early even with precip. gfs_t2m_b_washdc_35.png It is but the euro has 2 runs in a row now shown an immovable wedge all morning with temps dropping throughout teh morning... Link to comment Share on other sites More sharing options...
kurtstack Posted December 4, 2013 Share Posted December 4, 2013 It all comes down to the initial wave. I would hardly be shocked if it came in juicier. So far the euro is the lightest solution overall with the front wave. At least we get to watch travel from the se to our door rather than wait for it to magically form nearby. The best part of overrunning imo. My guess is the Euro may be modeling the dry air mass better, and adjusting precip amounts due to virga. I'm sure the radar will look fantastic for a while before we ever see a flake/ice pellet/raindrop. Link to comment Share on other sites More sharing options...
Bob Chill Posted December 4, 2013 Share Posted December 4, 2013 in other news... the euro brings another wave from the gulf d8-10 but our cold airmass retreats like the Federals at Bull Run Link to comment Share on other sites More sharing options...
HM Posted December 4, 2013 Share Posted December 4, 2013 Matt brings up a good point, too, about the snow/sleet foundation, which may hold the in-situ CAD wedge longer. Once you lose the sun, you could see a decent period of glazing potential on untreated pavements 4-9pm NW suburbs. Link to comment Share on other sites More sharing options...
H2O Posted December 4, 2013 Share Posted December 4, 2013 It is but the euro has 2 runs in a row now shown an immovable wedge all morning with temps dropping throughout teh morning... I assume that this is due to a more northerly wind direction for longer times before an easterly component? Link to comment Share on other sites More sharing options...
Bob Chill Posted December 4, 2013 Share Posted December 4, 2013 That's been the case the past three winters, but not in our slightly more distant past. The late January '09 mess held on more or less as expected with a nice glaze. Super Tuesday '08 was the same story with the late evening upgrade to Ice Storm Warnings when it became clear we weren't spiking to 50 degrees overnight. Of course, if you go further back to 1/99 and Jan through Feb 94 you have multiple more examples of prolonged periods of ZR-- but those were the ice storm winters. Yes, I'm tainted. Those previous better scenarios feel like the long lost good ole days now. Regardless, the models are converging on a very interesting and fun solution. I have nothing to complain about. The strength and depth of the CAD won't be resolved until saturday...or even nowcast time. Link to comment Share on other sites More sharing options...
clskinsfan Posted December 4, 2013 Share Posted December 4, 2013 Am I seeing dew points in the -15's for Sunday morning? Or am I miss reading that? Link to comment Share on other sites More sharing options...
Ian Posted December 4, 2013 Share Posted December 4, 2013 It is but the euro has 2 runs in a row now shown an immovable wedge all morning with temps dropping throughout teh morning... I'd guess there will be some cooling as the precip arrives though I wouldn't go with the coldest guidance for now. Winds end up with a marine component by 12z on the Euro so hard to be totally confident it stays super cold. I don't see the cooling during the day on the Euro maps I have. I'm mostly focused on DC and the immediate surrounds. Definitely easier to stay cold further west of course. Link to comment Share on other sites More sharing options...
snow. Posted December 4, 2013 Share Posted December 4, 2013 Matt brings up a good point, too, about the snow/sleet foundation, which may hold the in-situ CAD wedge longer. Once you lose the sun, you could see a decent period of glazing potential on untreated pavements 4-9pm NW suburbs. I am not as worried about ground temps as others (perhaps foolishly). - We are in the 30s by 10pm Friday.....It is december and the sun is useless Link to comment Share on other sites More sharing options...
snow. Posted December 4, 2013 Share Posted December 4, 2013 I assume that this is due to a more northerly wind direction for longer times before an easterly component? I think so...as soon as we go easterly we change over...like that second Link to comment Share on other sites More sharing options...
DCAlexandria Posted December 4, 2013 Share Posted December 4, 2013 We are approaching peak low sun angle Link to comment Share on other sites More sharing options...
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