From the ABC 7 Weather team

Washington Snow: Another Close Call (Update)

March 24, 2013 - 02:15 PM
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Snow? You've heard this before




UPDATE (9:30PM - Alex Liggitt): So I'm sitting here watching Twister on ABC Family channel wondering where spring is. Light snow continues to fall across the D.C. area, which some have called white rain. Heard that from @capecodweather on twitter, pretty funny but true.


Snow in Charlottesville earlier Sunday from Melissa Paige

Surface temperatures in the D.C. area have continued to stay above freezing besides Winchester at the 9 o'clock hour which sits at 32. I've seen some reports of snow sticking to grass, decks and elevated things such as cars but not really to the roads yet which is good. This will change heading late tonight going into the morning hours, particularly in the far western suburbs along and west of the Blue Ridge. The first batch of precipitation is exiting the region, while the next batch will enter early tomorrow morning.

The Winter Weather Advisory has been expanded east to Montgomery and Howard Counties in MD now which is in effect from 4am to Noon Monday. The thought is there will be moderate to heavy snowfall at times in some localized areas tomorrow morning which will impact the morning commute. In any heavy bands, some slushy or slick spots may form on the area roadways, so be sure to get up early, check for closings and delays, and give yourself some extra time to get to work.

Some local models bring in this more moderate to heavy snow in the early morning hours just before sunrise which would be a terrible way to start the morning in D.C. given the commute. Snow will continue through lunchtime before tapering to scattered snow showers through the afternoon hours. Temperatures in D.C. should remain above freezing, so it will be tough for accumulations unless there is a heavier band that sets up overhead. Just west of D.C., there will be cooler air available, so accumulations will be possible, though they are expected to be light (1-3") and lead to those mentioned slushy slick spots. Higher totals (4"+) will be possible in the higher elevations of the mountains and Shenandoah Valley. Be sure to watch Steve Rudin tonight at 11pm and catch Adam Caskey early tomorrow morning at 4:30am on ABC 7 News.


UPDATE (4:30PM - Adam Caskey):  CHART road temperatures are generally in the upper 40s throughout the metro area, and most of Maryland (we don't have data for Virginia), so even once it begins snowing in the metro area, it'll melt on contact with the roads.  Heavy enough snow can overcome the warm roads and cool the road surfaces enough for snow to accumulate, but that will most likely be far west of the I- 95 corridor - similar to last Monday morning.  This is why most accumulations should be minor and mostly on grassy surfaces in the metro area.  That is, unless temperatures take an unexpected drop.  The farther west you are from I-95, the more likely your roads and side streets are of having a coating of snow by tonight and Monday morning. Road temperatures:


Road temperatures as of 4:30pm Sunday

Here's a snapshot of Live Super Doppler Radar, which can always be found here. Keep in mind that not everything you see on the radar right now is hitting the ground as the air is still saturating along the leading edge of the precipitation.

Live Super Doppler 7 radar at 4:45pm Sunday

I know.  Oh boy I've heard this talk of snow already too many times this winter and now it's spring so STOP IT!  But even though today the temperature is in the 50s and roads temperatures under the strong March sun are in the 60s, there is a risk (right now 50% chance) of enough slushy wet snow by Monday morning to be causing problems for the Monday morning commute for the western and northern suburbs.  The storm that is just forming  in the western Great Plains 


By Sunday will move to the east and very likely (70% chance) follow a path of previous storms this winter, that is move to near Ohio and then reform just off the North Carolina and Virginia Coast Sunday night and Monday.  The ground is warm and the lower air is warm with a strong March sun most of the precipitation in the metro area is likely (70% chance) to be rain.  But once again by late Sunday night and Monday, as the storm reforms, that rain-snow line is likely to be right along the I-95 corridor.  Here is a look at the rain-snow probability line from a high resolution simulation of the storm from SUNY Stony Brook 


As in previous storms high spots (500 feet and higher) are likely (70% chance) to see some heavy wet snow into the Monday morning commute.  The storm again poses a threat, depending on the exact track as the storm begins to reform, of bringing heavy snow to the northeast and New England.  The latest snowfall accumulation for our area from NWS. 







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