wpostServer: http://css.washingtonpost.com/wpost

The Post Most: Local

Posted at 05:00 AM ET, 11/04/2012

D.C. area forecast: Staying cool ahead of potential midweek storm; could it really snow?

Originally posted at 5 a.m., updated at 3 p.m.

Freeze Warning 4-8 a.m. Monday for Fauquier, Loudoun, Frederick, Montgomery, and Howard counties. Protect tender vegetation.

EXPRESS FORECAST

Today: Partly sunny to mostly cloudy, cool. Low 50s. | Tonight: Partly cloudy. 30s. | Tomorrow: Partly to mostly sunny. Near 50 to low 50s. | A Look Ahead | Get Express Forecast by E-mail

TODAY'S DAILY DIGIT

A somewhat subjective rating of the day’s weather, on a scale of 0 to 10


Same partly to mostly cloudy chill as Saturday gets same score, but minus 1 for earlier sunset. Get the Digit on Twitter | Discuss on Facebook

SNOW POTENTIAL INDEX

A daily assessment of the potential for *accumulating* snow for the next week on a 0-10 scale. More info


SPI: 2 - Midweek coastal storm brings out the SPI. Not ideal setup for accumulating snow, but enough potential to watch closely. Get the SPI on Twitter | Discuss on Facebook

FORECAST IN DETAIL


It feels a lot more like early December out there than early November as we remain well on the cool side of normal for this time of year. Even when the sun comes out - some spots today, more spots tomorrow - an influx of cold air from the north still keeps temperatures from making much headway. Well, at least it’s dry for now. Come midweek, a coastal storm system brings a chance of rain and, yes, the potential for our first snowflakes of the season.

Today (Sunday): Not a whole lot changes today compared to recent days. A weak system slides by to our south, which should be enough to keep a fair number of clouds around. Overall we’ll call it partly sunny to mostly cloudy, with more clouds the further south you are and more sun the further north. We’re still on the cool side with highs topping out in the low 50s, about 10 degrees below normal. Confidence: Medium-High

Tonight: With the time change, sunset arrives abruptly at 5:04 p.m. in D.C. this evening. As we go through the evening, partly cloudy skies set the scene for another rather cool night across the area. Many spots may see frost toward morning as overnight lows fall to the low-to-mid 30s in the suburbs and mid-to-upper 30s downtown. Confidence: High

Keep reading for the latest on the midweek storm potential...

Tomorrow (Monday): High pressure heads for our area during the day tomorrow and should turn our skies partly to mostly sunny. Unfortunately, that high pressure has Canadian roots, so even with the sun we don’t see improvement in the temperature department, with highs near 50 to the low 50s. Confidence: Medium-High

Tomorrow night: The forecast calls for mostly clear and calm conditions into the overnight, and if we add those up, it comes out to cold. Expect overnight lows within a few degrees of freezing - as high as the mid-30s downtown and as low as the upper 20s in the burbs. Confidence: Medium-High

A LOOK AHEAD

A high-pressure center near us Monday night retreats northeast over New England on Tuesday, and clockwise flow around it keeps cold air trapped on our side of the Appalachians. We should see some Election Day sun, but a developing coastal storm to our south could send clouds into the mix as well. The entrenched cool air and any clouds combine to limit highs to the upper 40s to low 50s. Confidence:Medium-High

Tuesday night, clouds increase and thicken. If that coastal storm comes up fast enough from the south, we could even see rain (20-30% chance), or a rain/snow mix north and west of D.C. (20% chance), overnight or toward morning. Lows reach the low-to-mid 30s. Confidence: Low-Medium

Wednesday into early Thursday is when we’re most likely to see precipitation from a storm tracking north along or near the coastline. But there are a few possible scenarios, all of which are in play for now: 1) Low pressure hugs the coast or even tracks a bit inland, giving us a good dose of rain and gusty winds; 2) The track is slightly off the coast and just right to pull in enough cold air for a mix of rain and snow. Even in this case, the storm would need to be fairly strong to produce accumulating snow in metro D.C., but it’s not out of the question; 3) The low tracks further off the coast, grazing us with a little rain or nothing at all. In any of the cases, Wednesday looks cold with highs only in the upper 30s to low 40s. Confidence: Low

By  |  05:00 AM ET, 11/04/2012

Categories:  Forecasts

 
Read what others are saying
     

    © 2011 The Washington Post Company