Winter Wx Outook: 1 in. + 1 in. = Two Snows In One...Maybe

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WINTER WEATHER OUTLOOK

Although the snow just missed us to the south last time (although, I might add, the National Weather Service was forecasting 2-4 inches when I was forecasting one or less...just putting that out there), we have not one, but two chances for up to an inch to finish off this week--which for us, means we'll probably get at least a snowflake or two...probably.

TONIGHT INTO TOMORROW MORNING:

Summary: The first system coming through will develop late tonight into early tomorrow morning, with a potential for minor to perhaps moderate impacts on the morning commute, especially on untreated or unplowed secondary thoroughfares. Whatever falls will be a dry snow, though so it'll be easy to get off the roads by the afternoon.

Timing: Snow could begin around or after midnight tonight. Light to moderate snow is most likely to fall in the 1-7AM period, and then anything left will definitely taper off by 10AM.

Accumulations: Although the National Weather Service officially forecasts 1-2 inches for our area, I expect an inch or less of dry powder due to us being on the fringes of the event (with more towards our south-southwest, very similar to the previous [non] event). I have moderate confidence (40%) that we'll see an inch (and only 5-10% we'll see more) and around 50%-60% that we'll get at least a trace . There is no real chance of a mix or freezing rain due to the very cold temperatures.

Impacts: Due to the period of very cold weather we've been having, snow should fairly readily accumulate on roads and other surfaces. However, given the fact that the snow will be very dry and powdery, it should be easy to clear, and treated main arteries shouldn't have much problem staying open. However, it could be a little slippery on back roads, especially in the 7-10AM period as any snow ends, but by noon, they should be fine as well. Some amount of visibility depletion might be expected in the 7-10AM timeframe due to any remaining snowfall and the light, powerdery snow, although winds will be light.

Action Plan: Stay tuned to local media and monitor conditions and closings in the morning to ensure it is safe to commute before 10AM, especially if you must travel a significant distance over back roads. If you live closer to DC, I don't expect too much to worry about, but be sure to take a visual and use caution before and while driving.

FRIDAY EVENING

Summary: A storm system called an Alberta Clipper (named for its region of orgin and fast speed) will swing through late afternoon into the evening hours this Friday. While snowfall rates could be moderate at times, places that get snow won't see it last for more than 4-5 hours, ensuring totals will be an inch or below across the region, and impacts light, although that depends on exactly when the storm hits in relation to rush hour.

Timing: Currently, based off model data, I expect snow to begin sometime around 4-5PM, although the variability in this number will determine whether this is a white and fluffy introduction to the weekend or a traffic ensnaring annoyance. Snow should, however, pull out by 10PM.

Accumulations: Although little official data is available from the NWS, I expect to again see less than an inch for Alexandria and the vicinity, with little chance for more and certainly a chance for less. Current confidence in seeing that is around 30 to maybe 40%, and although my general feeling is that we'll probably see at least something. No real chance of ice/sleet/freezing rain/craziness like that though.

Impacts: As mentioned earlier, it all depends on when it falls. If it does start around 4-5PM, it could make the evening rush a little slippery, but not a major hazard. If it starts an hour earlier, it could really slow things down, and an hour later, and its just a fun curiosity.

Action Plan: I'll have an update tomorrow or early Friday, depending on conditions, so staying tuned for that would be your best bet. Otherwise, think about starting your evening commute a little earlier, but I wouldn't start buying portable generators and emergency rations just yet.

In other news, we could see "pockets of freezing rain" Monday but I'm pretty skeptical we'll be in one of them. If this does develop into something more than a hypothetical, I'll be sure to let you all know. Thanks, and enjoy the snow...assuming, of course, we don't strike out both our next chances at bat.

UPDATE: Tomorrow evening or Friday morning depending on conditions

C. A. M. Gerlach