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Posted at 05:00 AM ET, 03/26/2011

Forecast: Cool day sets the stage for some snow

Light accumulation possible

Today's Daily Digit
 
A somewhat subjective rating of the
day's weather, on a scale of 0 to 10.

 
Still chilly 40s, but it's the weekend and at least we see a little sunshine.
 
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EXPRESS FORECAST

Today: Partly sunny. Mid-to-upper 40s. | Tonight: Mostly cloudy, light snow late. Mid-20s to near 30. | Tomorrow: Morning snow showers, clearing late. Mid-30s to near 40. | A Look Ahead | Get Express Forecast by E-mail

FORECAST IN DETAIL

With the chance of snow tonight, a look back at past accumulations (.1”+) on March 27 or later shows how rare such is this late in the season at D.C. Though it last occurred in 2007, and before then in 1990 (both April 7), there have been seven instances since 1948. Of those, only twice has D.C. topped 1” -- on consecutive days to close March 1964. Besides a snow threat, the cold tomorrow is a pretty big deal, especially if we stay in the 30s. The last time D.C. has done that on the 27th or later? 1970 (3/30). And it has only happened 26 times in the past 140 years. Ahh, spring… where did you go?

Snow Potential Index: 5 (→) - Odds still good we see some snow falling early Sunday. But we're living on the edge.
 
The SPI is a daily assessment of the potential for accumulating snow for the next week on a 0-10 scale. Get the 'SPI' on Twitter
 

Temperatures: Latest D.C. area temperature map powered by iMapWeather (base map by Google). Click and hold on map to pan. Double-click to zoom. Refresh page to update. See larger map on our Weather Wall.

Today (Saturday): Putting aside the fact that we’re running about 10-15 degrees below normal, this won’t be a terrible day to be outdoors -- National Marathon or Cherry Blossom Festival anyone? -- and it’s probably the pick of the weekend for many. We’ll see periods of clouds, but overall it’s a partly sunny day. Morning temperatures climbing through the 30s and above top out in the mid-and-upper 40s. Those clouds may noticeably increase around or prior to sunset as the approaching storm begins to make itself known locally. Confidence: High

Tonight: Clouds thicken up during the evening, but we stay dry through at least midnight. After midnight (say, 2 a.m. to 5 a.m.), light snow should move in from the west and south. We’re on the northern edge of this system, so most of the snow is light, but some moderate bursts are also possible. Temperatures dip into the mid-20s to near 30 as precipitation gets going, and whatever falls would accumulate, at least a bit. Some slick spots are possible, particularly on untreated sidestreets. Confidence: Medium

How long does the snow last into Sunday? Keep reading to find out...

Tomorrow (Sunday): Depending on the track of the storm, snow showers may persist into the morning or taper off around sunrise -- later for places well south/southeast of the city. As the powerful late-March sun rises, accumulation becomes trickier, especially on roadways which should mostly be major-trouble free. By afternoon, we’re probably drying out, and there could even be a ray or two of sunshine before sunset. “Highs” reach the way-too-chilly-for-spring middle 30s to near 40. Total accumulation between a coating or less (especially north) to about 1” or a little more (especially southwest) is possible. Confidence: Medium

Tomorrow night: Light winds, dry air, clearing skies and perhaps a little snow on the ground help make this quite a cold night for the time of year. Some of the outer suburbs seem pretty likely to make a run toward 20 degrees, while downtown D.C. may stay closer to 30. If you’re out, dress warmly and watch for some re-freeze in any locations that remain wet from earlier precipitation (or snow melt). Confidence: Medium

A LOOK AHEAD

We start the week with better weather than the weekend features. On Monday, cool air remains, but skies should be partly-to-mostly sunny. Temperatures rise into the mid-and-upper 40s. After another cold night with most spots near or below freezing, Tuesday also dawns bright and the sunshine persists through the day. Temperatures warm a bit more as well, as highs reach the upper 40s and lower 50s. Confidence: Medium

By  |  05:00 AM ET, 03/26/2011

Categories:  Forecasts

 
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