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Posted at 05:00 AM ET, 12/07/2011

Forecast: 1-3” of rain through evening; may end as low-impact wet snow tonight

updated at 8:30 a.m.

Winter Weather Advisory northern suburbs (NWS calling for 1-2” there; see map )
Flood Watch this afternoon through late tonight

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

 
Rain, with the heaviest possibly during the a.m. and p.m. commutes. Plus no sun. Together = no fun.
 
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EXPRESS FORECAST

Today: Cloudy with rain, heavy at times. Temps falling through the 50s. | Tonight: Rain changing to snow, breezy. Accumulations light, if any. Low-to-mid 30s. | Tomorrow: Mostly sunny. Mid-40s. | A Look Ahead | Get Express Forecast by E-mail

FORECAST IN DETAIL

Remember our minor snow event back on Oct. 29? We’ve got a similar situation tonight with colder air moving in from the west/northwest as precipitation prepares to exit to the east/northeast. There’s potentially enough of an overlap to produce a light snow accumulation late tonight, mainly on grass and especially the further north and west you go from the District. Before then, this rather juicy storm systems produces sometimes heavy rain today, and afterwards we’re in for a stretch of sunny but cold days Thursday through the weekend.

Snow Potential Index: 5 (↑) - Parts of the metro area could see a light accumulation late Wed night, mainly on grass and especially north & west of town.
 
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
 

Today (Wednesday): Rain today is heavy at times with many spots getting 1-3” through evening. The rain is probably heaviest in the early-to-mid morning and then again late afternoon into evening (doesn’t look good for either the morning or evening commutes). In between, I think we’ll see lighter showers or maybe even a break at some point. Temperatures fall through the 50s, dropping to near 50 later in the day as breezes from the northwest bring in colder air. Confidence: Medium-High

Tonight: As evening temperatures drop into and through the 40s, rain is fairly heavy before likely changing to snow from west to east across the area between approximately 8 p.m. and 1 a.m. The snow may fall as or mix with sleet for a time during the changeover. The snow exits to the east/northeast between approximately 1 a.m. and 4 a.m. Lows fall to the low-to-mid 30s and evening/overnight winds blowing at 15-25 mph from the northwest with higher gusts. Confidence: Low-Medium


Snow potential for Wednesday night. Most accumulation limited to grassy areas (except high elevations N & W).
Accumulation? Downtown and to the south and east, overnight temperatures falling into the mid-30s mean we’ll probably see no accumulation or maybe up to a coating on grass in those areas. North and west, low-to-mid 30s could be cold enough for a coating to 1” mainly on grass, but with whitening of the ground possible the further north and west you go (e.g., toward Frederick and Loudoun counties). See adjacent map for more detail. Confidence: Low-Medium

Accumulation confidence: There’s still time for changes in the storm track and in how fast and strong colder air moves in tonight. So, the accumulation forecast could go up or down a bit (not that there’s a ton of room to go down). Even if colder air moves in faster and stronger than anticipated, though, odds are very low this turns into a major storm since the precipitation will be on its way out.

For related traffic news, check out Dr. Gridlock. Keep reading for the forecast through the weekend...

Tomorrow (Thursday): The rain, the snow - it’s all outta here before sunrise. While roads may still be wet, I don’t expect anything white on the pavement for the morning commute. There may be a few early-morning slick spots, mainly north and west, where temperatures get down to freezing or just below. As high pressure builds in, mostly sunny skies dry us out, but don’t do much for temperatures which only manage highs in the mid-40s. Lingering morning breezes diminish in the afternoon. Confidence: Medium-High

Tomorrow night: Calm winds and partly cloudy skies make fore an uneventful Thursday night as far as the weather goes. Lows bottom from the mid-20s (suburbs) to low 30s (downtown). We’re still waiting for Reagan National Airport’s first freeze of the season. This could be it, or we may fall just short. Confidence: Medium-High

A LOOK AHEAD

Friday through Sunday brings yet another stretch of calm weather coinciding with a weekend. Skies should be partly to mostly sunny, but December does finally catch up with us in the form of fairly cold temps. Highs stall in the mid-40s to near 50 Friday, low-to-mid 40s Saturday, and 40s on Sunday. Nighttime lows cool from the upper 20s to mid-30s (suburbs to city) Friday night, to the low 20s to near 30 (suburbs to city) Saturday night. Confidence: Medium-High

By  |  05:00 AM ET, 12/07/2011

Categories:  Forecasts

 
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