Winter Storm on Track, School Forecast

Storm Update

11 PM UPDATE: The temperatures are much lower than initially forecasted, and it seems as if we will get very little, if any rain. In addition, the storm is picking up intensity, and thundersnow is verypossible tomorrow morning.  This is supported by the latest forecast models.  I'm upping the storm totals to 8-16 inches, with 3-6 possible tonight alone.   

The winter storm is starting to make its way into the area, and while it may start out as a bit of drizzle, precipitation will quickly switch over to snow overnight. I'm sticking with my initial forecast of 6-12 inches, with more possible northwest and less southeast.  While the temperatures now are too warm for snow, in the lower 40s, the dew points are in the low twenties, so once precipitation starts, evaporative cooling in the atmosphere will allow snow to fall, relatively quickly after the onset of precipitation. 

School Prediction

At this point, it is almost a foregone conclusion that school will be closed tomorrow (Wednesday), as it will be snowing throughout the day, and at least 2-4 inches will have already fallen overnight.  I wouldn't be surprised if MCPS and other area school systems announced closings sometime tonight.  Since latest guidance suggests that the snow will taper off late Wednesday night, school will also probably closed Thursday, if everything goes according to plan.  Friday is more iffy, but a delay or even closing is not out of the realm of possibility. 

I'll post another update tomorrow morning as the snow starts to ramp up (hopefully).

Major Snowstorm to Impact Area Wednesday

A major and potentially crippling snowstorm seems all but certain to impact Washington D.C. on Wednesday. While temperatures will not be ideal, the heavy precipitation will cool the atmosphere enough for some significant snowfall in the area, the likes of which have not been seen for over two years.

Precipitation Details

The models are pretty much in consensus in forecasting 1.25-2" of precipitation to fall in the area.  IF accompanied with the 10:1 or 15:1 ratios that are often in January and February, we could be talking about one of the largest snowstorms in DC history.  However, due to temperatures that will hover around freezing the whole event, we will rather see ratios of around 7:1 or 8:1, and it is not out of the question that rain could mix in on Wednesday, which could drive down totals to the 3-6" range. However, this looks unlikely at the moment.  Still, this will be a very wet snow that could stick to the power lines and, combined with moderate winds, cause some power outages.

Timing

The first effects of the storm will be felt Tuesday evening, starting as light rain.  As it gets colder and temperatures fall overnight, it will start mixing and eventually switch over to all snow.  The snow will get heavier throughout the night, and will continue during the day Wednesday, until it tapers off Wednesday night.  It is also possible that some rain could mix in during the day Wednesday, but this seems unlikely, especially north and west of the District.

Impact

I would predict around 6-12 inches of snow throughout Montgomery Country, with 12 or more inches being more likely out west near Poolesville, with 6 or so inches more likely near Silver Spring. Along with this, schools have a very high chance of closing Wednesday, a good chance of closing Thursday, and may be delayed Friday.

UPDATE: Latest guidance suggests the possibility that the temperatures do not fall enough and that this is mostly rain, with a couple of inches of snow on the front and back end of the storm.  While unlikely, it is important to remember that this remains a possible scenario.

I'll post another blog update tomorrow afternoon, and minor updates on Twitter, where you can follow me @samdman95