New guidance suggests snow threat growing
The evening models are beginning to come out. Every 30 minutes or so I'll post a short update covering the new computer guidance and any valid side commentary I come across as they roll.
1:05 a.m.: The Euro has also come in colder with a decent snow hit across the region as the upper-level energy passes. Verbatim it would be a at least a moderate snowstorm around here. Pretty much all guidance from tonight suggests a pretty good dump of snow across the area late Wednesday into Wednesday night. It would appear some western suburbs may stay all snow, and that rain ahead of the system to the east may be less than thought. This is not a forecast, and temperature issues remain, but snow lovers with insomnia should sleep well...
11:45 p.m.: The story tonight has been a good one thus far for area snow lovers. Both American models are pumping out the opportunity for a few inches (or more) of snow late Wednesday into Wednesday night as the upper-level energy associated with the upcoming storm passes by. In addition to support from the RGEM noted earlier, the Canadian GGEM also shows a similar scenario. Temperatures remain a concern. However, the odds for snow of note seem to be rising as numerous models converge on that type of solution.
We'll check back in again for those staying up for the Euro (comes in at 1 a.m.) plus perhaps another tidbit or two before then.
Keep reading for more on the snowy NAM and GFS runs.
11:10 p.m.: Check out this GFS snow map based on tonight's run.
Big cities..rain to snow, with heaviest thump in nw burbs ( dc to PHL) DC to BWI, biggest snow of year.. harrisburg, allentown also ie.
10:55 p.m.: The GFS is out through the storm and it is at least a bit cooler than its previous run aloft if not quite as cool as the NAM. At hour 42, 48, and 54, you can see a similar passage of an area of rain rapidly changing to snow across the region. Looks like a big snow hit here at first glance though maybe less of one than the NAM.
10:30 p.m.: The RGEM (from Canada) is showing snow across much of the area -- especially the western half -- at 48 hours on tonight's run with a fairly strong low close to the Virginia coast. The 0z GFS will be running shortly.
10:00 p.m.: Wes Junker commented that on the NAM, any precipitation falling after 7 p.m. Wednesday would easily be all snow in D.C. with the transition happening somewhere between 4 p.m. and 7 p.m. Here's the NAM's simulated radar at 7 p.m. CWG commenter bdeco makes a statement worth repeating about the NAM's tendency to overdo precipitation amounts. Not that we know this is the case here, but it is worth considering. The Global Forecast System (GFS) starts to run around 10:30 p.m.
9:45 p.m.: Jim Cantore is excited about the NAM it seems...
The highest storm total for THIS SEASON SO FAR in DC is 1.4" @ Dulles and 1.5" @ National. New NAM CRUSHES these totals with pending storm.
9:30 p.m.: The NAM looks pretty exciting for area snow lovers at first glance. Warm air's reach is minimal yet again (like the 18z run) and the model spits out plenty of precipitation (Hour 48 | Hour 54) with cold temperatures above the surface. Verbatim, the area picks up quite a bit of precipitation mainly in the form of snow. AccuWeather's Henry Marguisity states the NAM is consistent with snow passing through D.C. and Baltimore, he even throws out some high numbers. This snow map from the NAM backs him up.
9:00 p.m.: First up, the 0z North American Mesoscale Model (NAM). It's out to hour 12 as of now, and the storm should be entering into our area around hour 30 or 36 (Wednesday morning) for those tracking along.
While we wait to see what it shows, here's a quick glimpse of the newest Short Range Ensemble Forecast (SREF) maps: Precipitation mean over .5" across the area, a low in similar position to recent models, and a decent mid level (500mb) track. Sometimes the SREF leads the way for the new NAM. If so tonight, I would not expect major changes from prior runs. We shall see...