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A moisture-laden storm system is surging northeast and has spread a layer of clouds over the region. The clouds have slowed the rise in temperatures with highs struggling to reach 50. Cold rain moves in tonight, perhaps even briefly mixing with sleet and snow particularly west and northwest of the District, before sunshine and a rebound in temperatures Friday.

Through Tonight: Clouds lower and thicken this evening with rain developing between 8 p.m. and midnight from southwest to northeast.  I can’t entirely rule out a little snow and/or sleet mixing in with the rain (best chance west and northwest of the beltway).  No snow accumulation is expected.  It’s cold overnight, with lows 36-40 (suburbs-city).  Total rainfall ranges from half an inch to the northwest to around one inch near the Bay and into southern Maryland.

Tomorrow (Friday): Rain ends around the morning commute with gradual clearing during the late morning hours.  Sunshine emerges during the afternoon, elevating temperatures to near 60.  Winds are from the northwest at 10-15 mph.

See Kathryn Prociv’s forecast through the weekend. And if you haven’t already, join us on Facebook and follow us on Twitter . For related traffic news, check out Dr. Gridlock.

Pollen: The cold weather has reduced tree pollen a bit. Tree counts are 14 grains per cubic meter which is LOW-MODERATE after yesterday’s counts around 30 (moderate).

Snow in Southwest Virginia:  A surprise shot of snow has developed around Roanoke, Blacksburg and Radford as the storm moving up from the south interacts with the lingering cold air mass over the region.  Winter weather advisories for 1 to 2 inches of snow are in effect through 8 p.m. (after which mostly rain is expected), with heavier amounts possible at high elevations.

In west central Virginia, Wintergreen ski resort reports it has an “astounding amount of terrain” to open this Saturday, the final day of its 2012-13 season.