B-Paq Posted February 12, 2014 Share Posted February 12, 2014 rap_ref_neng_15.png Hope you guys are right about the RAP having a slight warm bias - move that 32 line south by about 5 miles and I'd get in on that ridiculous band Link to comment Share on other sites More sharing options...
Ian Posted February 12, 2014 Share Posted February 12, 2014 Didnt see this posted yet http://www.spc.noaa.gov/products/md/md0091.html MESOSCALE DISCUSSION 0091 NWS STORM PREDICTION CENTER NORMAN OK 1242 PM CST WED FEB 12 2014 AREAS AFFECTED...VA...SE WV CONCERNING...HEAVY SNOW VALID 121842Z - 130045Z SUMMARY...MODERATE TO HEAVY SNOW IS EXPECTED TO DEVELOP THIS AFTERNOON FROM SERN WV EWD ACROSS MUCH OF VA. SNOWFALL RATES OF 1 INCH PER HOUR WILL BECOME COMMON WITH LOCALLY HIGHER RATES. DISCUSSION...LATEST WATER VAPOR IMAGERY SHOWS AN UPPER-LEVEL TROUGH IN THE MS VALLEY WITH A LEAD SHORTWAVE TROUGH EXTENDING FROM THE SRN APPALACHIAN MTNS SEWD ACROSS SC. WIDESPREAD PRECIPITATION IS LOCATED JUST AHEAD OF THIS FEATURE IN A BROAD ZONE OF WARM ADVECTION FROM ERN GA NEWD INTO THE CAROLINAS. MODEL FORECASTS SUGGEST LARGE-SCALE ASCENT ALONG THIS ZONE WILL MOVE NWD OVER THE NEXT FEW HOURS BECOME INCREASINGLY ENHANCED ACROSS NRN NC AND VA LATE THIS AFTERNOON. THIS WILL AID THE DEVELOPMENT OF MODERATE TO HEAVY SNOWFALL ACROSS VA AND SERN WV LATE THIS AFTERNOON. THE 18Z SOUNDING FROM GREENSBORO NC SHOULD BE REPRESENTATIVE OF THE AIRMASS IN VA...SHOWING THE PRIMARY ZONE FOR DENDRITIC GROWTH BETWEEN 700 AND 500 MB. AS MOISTENING CONTINUES TO OCCUR BELOW 850 MB...AN ISOTHERMAL LAYER SHOULD BE FAVORABLE FOR HEAVY SNOW WITH RATES OF 1 INCH PER HOUR COMMON. LOCALLY HIGHER RATES COULD OCCUR WITHIN THE MORE ORGANIZED BANDING. ..BROYLES.. 02/12/2014 ATTN...WFO...AKQ...LWX...RNK...RLX... obs thread is where this stuff should be Link to comment Share on other sites More sharing options...
EastCoast NPZ Posted February 12, 2014 Share Posted February 12, 2014 We may get rates over 5''/hour for short periods tonight. Back in 1987 thundersnow led to reports of 6'' of snow in TEN minutes locally. Do you have any links to verify? That sounds pretty impossible. Link to comment Share on other sites More sharing options...
WeSuck Posted February 12, 2014 Share Posted February 12, 2014 We may get rates over 5''/hour for short periods tonight. Back in 1987 thundersnow led to reports of 6'' of snow in TEN minutes locally. That is just sick. I bet visibilities would be negative during that! Link to comment Share on other sites More sharing options...
Solo2 Posted February 12, 2014 Share Posted February 12, 2014 We may get rates over 5''/hour for short periods tonight. Back in 1987 thundersnow led to reports of 6'' of snow in TEN minutes locally. I don't know about that, but we did get something like 12" 5 hours in FDK during one of the 09-10 storms.... Link to comment Share on other sites More sharing options...
Bob Chill Posted February 12, 2014 Share Posted February 12, 2014 I want HM or Coastal to stop back by and tell me that my expectations of +TSSN somewhere in our area is not just a weenie wishcast. Link to comment Share on other sites More sharing options...
Deck Pic Posted February 12, 2014 Share Posted February 12, 2014 This is what I posted to the public - Final Call for DC Proper - 8"-10"Evolution: - Snow starts between 7-9pm, becomes heavy late evening and overnight- Snow may mix with sleet at times toward dawn and perhaps change over around dawn- Quasi - Lull mid-morning to mid-afternoon with light mixed precip, maybe even a little rain/freezing rain- Snow redeveloping late afternoon, moderate at times, and tapering off to light snow/flurries after 9pm Link to comment Share on other sites More sharing options...
mdsnowlover Posted February 12, 2014 Share Posted February 12, 2014 That is just sick. I bet visibilities would be negative during that! that would be white out conditions. seen it twice in my 65 years, both times I got 2 ft of snow Link to comment Share on other sites More sharing options...
WxMan1 Posted February 12, 2014 Share Posted February 12, 2014 I still like CWG 5-10 for the city and less for me....more like 3-6 or 4-6. I'm not sure of the rationale for lowering Annapolis as I don't see the surface temps being a big problem. The warm layer will be aloft. Wes, very true. We talked about this over the weekend at work, when this system was into the medium range via those runs of the EC/CMC/UK; I think we'd more likely see a cutoff in accums more so because of mid level dry slotting (above the -10C isotherm) than the BL or even an elevated warm layer (900-800 mb thermals). Often times they go hand-in-hand, i.e. we don't get the additional diabatic cooling from precipitation rates within the dry slot, thus the drizzle/freezing drizzle or light sleet. Either way, I see NO reason why forecasters cannot be bullish on the front end snowfall, given the antecedent thermal conditions, unless we get convective disruption early on in the process (offshore) that would lower our QPF through 12Z. I still like the CWG's forecast from yesterday too, as well as yesterday afternoon's LWX map for areas along/east of I-95, while the latest forecast snowfall for areas west of I-95. In other words, yes, I like the idea of boosting amounts w-nw, but not at the expense of lowering totals east toward the Bay. Low level thermals will not be a problem through 12-15Z. Link to comment Share on other sites More sharing options...
RickinBaltimore Posted February 12, 2014 Share Posted February 12, 2014 Thanks to all the experts for analysing this as always. Hopefully we get a good show! Link to comment Share on other sites More sharing options...
smokeybandit Posted February 12, 2014 Share Posted February 12, 2014 My forecast downgraded to 3-5" Link to comment Share on other sites More sharing options...
WxUSAF Posted February 12, 2014 Share Posted February 12, 2014 Bob…I looked at 12z NAM profiles and didn't see a layer that looked unstable around us. But CSI bands wouldn't show up on that and with the rockin' frontogenesis over us, we will likely see that. Link to comment Share on other sites More sharing options...
MN Transplant Posted February 12, 2014 Share Posted February 12, 2014 NAM running. Start time in the Beltway ~7pm. Link to comment Share on other sites More sharing options...
Subtropics Posted February 12, 2014 Share Posted February 12, 2014 Do you have any links to verify? That sounds pretty impossible. Ask Jebman. He has spoken about it to me a few times. Would have to do some digging to find sources. Link to comment Share on other sites More sharing options...
Deck Pic Posted February 12, 2014 Share Posted February 12, 2014 This is LWX's forecast as of 45 minutes ago..stop worrying about point and clicks https://www.facebook.com/photo.php?fbid=619519248114895&set=a.209993759067448.49515.209863609080463&type=1&theater Link to comment Share on other sites More sharing options...
WEATHER53 Posted February 12, 2014 Share Posted February 12, 2014 Feel like I can post my hourlies thru 3am then sleep some. The animation continues the backlash for hours, that's pretty rare for here. Final piece is how much mixing and that wil be revealed by a "m outh of Bay" track verus between Norfolk and Va Beach. Link to comment Share on other sites More sharing options...
Bob Chill Posted February 12, 2014 Share Posted February 12, 2014 You can see a much broader expanse of the western heavy precip and less convection type precip over obx. This run is going to smoke us. Link to comment Share on other sites More sharing options...
Scuddz Posted February 12, 2014 Share Posted February 12, 2014 Bob…I looked at 12z NAM profiles and didn't see a layer that looked unstable around us. But CSI bands wouldn't show up on that and with the rockin' frontogenesis over us, we will likely see that. There's gotta be CSI all over the place with rates being forecast. I wouldn't be surprised at a rumble or two. Link to comment Share on other sites More sharing options...
MN Transplant Posted February 12, 2014 Share Posted February 12, 2014 NAM is a touch faster. Heavy snow here just after midnight. Almost 1" QPF by 09z. Link to comment Share on other sites More sharing options...
Deck Pic Posted February 12, 2014 Share Posted February 12, 2014 Nammed Link to comment Share on other sites More sharing options...
chris87 Posted February 12, 2014 Share Posted February 12, 2014 You can see a much broader expanse of the western heavy precip and less convection type precip over obx. This run is going to smoke us. hours and hours of really good rates Link to comment Share on other sites More sharing options...
snowfan Posted February 12, 2014 Share Posted February 12, 2014 Crush job on the NAM. Foot totals reach DC by H17. Link to comment Share on other sites More sharing options...
MN Transplant Posted February 12, 2014 Share Posted February 12, 2014 Foot of snow in the DC metro by 6am. A beautiful run. Link to comment Share on other sites More sharing options...
Bob Chill Posted February 12, 2014 Share Posted February 12, 2014 This is sick. You can see what's going on down by rdu already. NAM has an exceptional track and column. We are in the crosshairs for a perfect evolution at all levels. Man. I'm trippin. Link to comment Share on other sites More sharing options...
stormtracker Posted February 12, 2014 Author Share Posted February 12, 2014 OMG. I don't even..... Link to comment Share on other sites More sharing options...
DCWeatherGuy Posted February 12, 2014 Share Posted February 12, 2014 This is what I posted to the public - Final Call for DC Proper - 8"-10" Evolution: - Snow starts between 7-9pm, becomes heavy late evening and overnight - Snow may mix with sleet at times toward dawn and perhaps change over around dawn - Quasi - Lull mid-morning to mid-afternoon with light mixed precip, maybe even a little rain/freezing rain - Snow redeveloping late afternoon, moderate at times, and tapering off to light snow/flurries after 9pm FWIW (extremely little, i know), I agree with every single bit of this. 8-10 seems like the sweep spot for DC. 6-8, followed by lull, followed by 2-3. The lull will be a nice chance to get outside with the kids and do some sledding. I've got a 3 and 4.5 year old who have never been on a sled ride. Looking forward to changing that. Link to comment Share on other sites More sharing options...
HM Posted February 12, 2014 Share Posted February 12, 2014 I want HM or Coastal to stop back by and tell me that my expectations of +TSSN somewhere in our area is not just a weenie wishcast. It is not a weenie wishcast. It is very legit. The "secondary circulation" on this frontogen machine is going to steamroll you guys tonight. I could see DC seeing double digit totals easily. There's gotta be CSI all over the place with rates being forecast. I wouldn't be surprised at a rumble or two. Deep-layer CSI forecasts from NAM look supportive of your statement but I haven't done an official check of stability through cross-sections (to rule out CI etc). Given the timing of this maturing cyclone, the synoptic setup and frontogen, I'm going to assume it's all CSI all night. I'm really happy for you guys in DC! Link to comment Share on other sites More sharing options...
olafminesaw Posted February 12, 2014 Share Posted February 12, 2014 Unfortunately the NAM has several hours of ice according to the instant weathermaps map, but I'm certainly not complaining. Link to comment Share on other sites More sharing options...
WEATHER53 Posted February 12, 2014 Share Posted February 12, 2014 The stuff about 6" in 10 minutes is wrong. What did happen is we got an inch in 10 minutes which would have been 6" per hour extrapolated. Manyt areas did report 2-3" in an hour with some suspect reports of 4. Link to comment Share on other sites More sharing options...
mappy Posted February 12, 2014 Share Posted February 12, 2014 18-20" showing up just west of DC Link to comment Share on other sites More sharing options...
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