Bob Chill Posted February 14, 2016 Share Posted February 14, 2016 Taking a second look at the rgem areas in west central VA ice up pretty good. RGEM punches the above freezing temps mostly into dc/md. Even just SW of DC has plenty of ice. Not sure I've seen temps progress like the rgem is showing often if ever Link to comment Share on other sites More sharing options...
RevWarReenactor Posted February 14, 2016 Share Posted February 14, 2016 I think that is right. Plus its hard to stay freezing rain with a deluge and marginal temps because freezing releases latent heat. Yeah, saw this last year. Pouring Rain and 31 degrees,it wasn't freezing rain. Link to comment Share on other sites More sharing options...
ers-wxman1 Posted February 14, 2016 Share Posted February 14, 2016 Last time I was in one of those maps, it was in the 40% chance of 4" or more and received .4" of snow. Yes but that was a very marginal situation to begin with. Air is plenty cold this go around. Link to comment Share on other sites More sharing options...
Windman18 Posted February 14, 2016 Share Posted February 14, 2016 FWIW, Hrrr has light snow in dc by midnight tonight. Link to comment Share on other sites More sharing options...
mitchnick Posted February 14, 2016 Share Posted February 14, 2016 Yes but that was a very marginal situation to begin with. Air is plenty cold this go around. Well then it was a poor forecast and we shouldn't trust that product if that's what we can get <24 hours out. Link to comment Share on other sites More sharing options...
snowfan Posted February 14, 2016 Share Posted February 14, 2016 The snowfan snow map. I'd probably change the 5-9 spot in the mountains to 4-8 based on latest guidance, but don't feel like editing. Link to comment Share on other sites More sharing options...
ers-wxman1 Posted February 14, 2016 Share Posted February 14, 2016 Ideal ice accretion occurs with temps below 30 and light precip over longer periods of time. Steady drizzle or light rain is best for icing. Heavier precip runs off. Link to comment Share on other sites More sharing options...
clueless Posted February 14, 2016 Share Posted February 14, 2016 Heck of a temperature gradient on the 4km NAM between DC and Leesburg. temp54.gif That defies the meaning of gradient. Link to comment Share on other sites More sharing options...
BaltimoreWxGuy Posted February 14, 2016 Share Posted February 14, 2016 Very light precip at DC by 7AM on GFS Link to comment Share on other sites More sharing options...
ers-wxman1 Posted February 14, 2016 Share Posted February 14, 2016 Well then it was a poor forecast and we shouldn't trust that product if that's what we can get <24 hours out. Not sure why I even bother to post Link to comment Share on other sites More sharing options...
BaltimoreWxGuy Posted February 14, 2016 Share Posted February 14, 2016 FWIW, Hrrr has light snow in dc by midnight tonight. Its virga, no accumulated precip has fallen thru end of HRRR run Link to comment Share on other sites More sharing options...
MacintoshPro Posted February 14, 2016 Share Posted February 14, 2016 Does anything other than the NAM support 4" in DC? 4" in DC is a pipe dream right now. I think 1-3" is reasonable.. 4" a "boom"... its seems weird. They don't even have 4" in SW VA where models have consistently put out those totals. Link to comment Share on other sites More sharing options...
ers-wxman1 Posted February 14, 2016 Share Posted February 14, 2016 Well then it was a poor forecast and we shouldn't trust that product if that's what we can get <24 hours out. A 10% probability of receiving 4" or more is not very high. Have to understand what the product is telling you. Link to comment Share on other sites More sharing options...
WxMan1 Posted February 14, 2016 Share Posted February 14, 2016 The latest NAM run sort of fits the conceptual model for these type of events. Having grown up and forecasted in the mid Atlantic for several years, we've seen this many times. Last year's 5-6" on a south wind was about as good of a front end thump as one could ask for around here (with the sfc high well offshore) -- a benchmark of sorts for WAA-only events. I like the idea of 2-4" with the front end as we scour out the arctic airmass in place (over/under for me is 2"), followed by light sleet/fz drizzle as we await the next WAA surge. Surface temps stay below freezing meanwhile because of the in-situ CAD -- i.e. those low dewpoints and wetbulbs helping out with the diabstic cooling early and with a snowpack and weak surface advection by Monday evening, where is the surface warming gonna come from (at least before the next WAA surge on Tue)? Very rarely in this type of a pattern we go from snow to sleet to mod fz rain or rain. We typically dry slot first (fz drizzle), then await the next wave several hours later. Link to comment Share on other sites More sharing options...
BaltimoreWxGuy Posted February 14, 2016 Share Posted February 14, 2016 SOuth DC near .1 precip by 1PM..so south suberbs around 1" at 1PM Link to comment Share on other sites More sharing options...
BTRWx Posted February 14, 2016 Share Posted February 14, 2016 http://www.wpc.ncep.noaa.gov/wwd/day2_psnow_gt_04.gif http://www.wpc.ncep.noaa.gov/wwd/day2_pice_gt_25.gif That's disappointing. Link to comment Share on other sites More sharing options...
BaltimoreWxGuy Posted February 14, 2016 Share Posted February 14, 2016 By 7PM 2" for pretty much everyone, even out west. Link to comment Share on other sites More sharing options...
ers-wxman1 Posted February 14, 2016 Share Posted February 14, 2016 That's disappointing. Yep...low probs Link to comment Share on other sites More sharing options...
BaltimoreWxGuy Posted February 14, 2016 Share Posted February 14, 2016 32F degree line straddles I95 at 7PM Link to comment Share on other sites More sharing options...
MacintoshPro Posted February 14, 2016 Share Posted February 14, 2016 GFS looks like 1-3" with the heavier precipitation south. Keeps surface temps below freezing until 03z Tuesday. Link to comment Share on other sites More sharing options...
Windman18 Posted February 14, 2016 Share Posted February 14, 2016 Its virga, no accumulated precip has fallen thru end of HRRR run Mostly, but the 0.01 precip line did just cross the va/md border and barely into dc. Link to comment Share on other sites More sharing options...
ers-wxman1 Posted February 14, 2016 Share Posted February 14, 2016 The latest NAM run sort of fits the conceptual model for these type of events. Having grown up and forecasted in the mid Atlantic for several years, we've seen this many times. Last year's 5-6" on a south wind was about as good of a front end thump as one could ask for around here (with the sfc high well offshore) -- a benchmark of sorts for WAA-only events. I like the idea of 2-4" with the front end as we scour out the arctic airmass in place (over/under for me is 2"), followed by light sleet/fz drizzle as we await the next WAA surge. Surface temps stay below freezing meanwhile because of the in-situ CAD -- i.e. those low dewpoints and wetbulbs helping out with the diabstic cooling early and with a snowpack and weak surface advection by Monday evening, where is the surface warming gonna come from (at least before the next WAA surge on Tue)? Very rarely in this type of a pattern we go from snow to sleet to mod fz rain or rain. We typically dry slot first (fz drizzle), then await the next wave several hours later. This is well written. Likely scenario Link to comment Share on other sites More sharing options...
BaltimoreWxGuy Posted February 14, 2016 Share Posted February 14, 2016 34-36 degrees for the cities by 1AM...pretty similar to last couple GFS runs Link to comment Share on other sites More sharing options...
Ian Posted February 14, 2016 Share Posted February 14, 2016 gfs blows.. but not sure what we're looking for anymore. Link to comment Share on other sites More sharing options...
BaltimoreWxGuy Posted February 14, 2016 Share Posted February 14, 2016 Mid to upper 40s by 7AM as the heavier rain begins to come in Link to comment Share on other sites More sharing options...
Bob Chill Posted February 14, 2016 Share Posted February 14, 2016 gfs blows.. but not sure what we're looking for anymore. I'm looking for 2" of snow. Gfs looks good Link to comment Share on other sites More sharing options...
WinterWxLuvr Posted February 14, 2016 Share Posted February 14, 2016 The second wave that had been mentioned is about to catch the first one on the gfs. Link to comment Share on other sites More sharing options...
DDweatherman Posted February 14, 2016 Share Posted February 14, 2016 Just don't see precip starting at 1am in DC possibly as indicated by short range guidance, but then take 15 hours to get to .2 QPF. Interesting now cast coming up in that regard Link to comment Share on other sites More sharing options...
Wonderdog Posted February 14, 2016 Share Posted February 14, 2016 Does anything other than the NAM support 4" in DC? 4" in DC is a pipe dream right now. True, unless something changes. NAM seems to be always overdone on precip. Link to comment Share on other sites More sharing options...
BTRWx Posted February 14, 2016 Share Posted February 14, 2016 Does anything other than the NAM support 4" in DC? 4" in DC is a pipe dream right now. Does this count? *Max Potential Map* Link to comment Share on other sites More sharing options...
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