D.C. area forecast: More snow on the way, likely enough for Monday delays

* Winter Storm Warning for immediate DC area and south, with Winter Weather Advisory for northern counties into Baltimore, from this evening through early afternoon Monday *

9:05 a.m. update: Overnight models are mostly unchanged. The European model, which had shown the least precipitation out of the major models, has nudged north with the storm and slightly increased amounts in our area. With that in mind, we’re unlikely to be lowering our snowfall forecast in our mid-afternoon update today. Depending on this morning’s model data, which arrives over the next few hours, we may at least consider raising the lower end of our forecast ranges, but at this point don’t anticipate dramatic changes.

From 6 a.m. …

Today’s Daily Digit

A somewhat subjective rating of the day’s weather, on a scale of 1 to 10.

6
As much as 20+ degrees colder than yesterday. But 40s aren’t terrible and precip should wait til late

Express Forecast

Today: Partly to mostly cloudy. Wintry mix late. Highs: Mid-40s.

Tonight: Wintry mix changes to snow. Lows: Mid-to-upper 20s.

Tomorrow: Snow tapers during the morning. Highs: Low-to-mid 30s.

FORECAST IN DETAIL

I’d say it’s hard to believe yet another winter storm is on the way after yesterday’s taste of spring. But really, it seems just about right the way this winter has gone. Snow lovers will rejoice as a wintry mix turns to snow this evening. A few inches are possible by Monday morning, most likely complicating the commute, giving some kids reason to cheer, and some adults reason to curse! An interesting twist to the forecast emerges Tuesday as another storm could impact the area, or it could miss us out to sea. Never a dull moment, huh?


Radar & lightning: Latest regional radar shows movement of precipitation and lightning strikes over past two hours. Refresh page to update. Click here or on image to enlarge. Or see radar bigger on our Weather Wall.

Today (Sunday): Early breaks of sun get fewer and farther between through the morning, with mostly cloudy skies by afternoon. A breeze from the north around 10 mph and the increasing clouds hold temperatures around 20-25 degrees below yesterday’s warmth with highs in the mid-40s. The leading edge of precipitation from our approaching winter storm likely arrives around 3-6 p.m. from southwest to northeast, probably in the form of a mix of rain and snow, with no accumulation expected through sunset. Confidence: Medium-High

Tonight: Our wintry mix transitions to all snow during the evening from northwest to southeast, possibly mixing with sleet during the changeover. The snow should have trouble accumulating at first, especially on roads, with early evening temperatures still in the upper 30s to near 40. Light accumulation, especially on untreated roads in the colder suburbs, becomes a threat after around 8 p.m. as temperatures drop into the mid-30s. The snow should start sticking everywhere after 11 p.m. or so, even on many treated roads inside the Beltway, as the snow falls moderately at times and lows drop to the mid-to-upper 20s. Confidence: Medium

Below is our latest thinking for snow totals. We will tweak this map *if needed* later today after reviewing overnight and morning model data.

CWG snowfall forecast, first issued Saturday at 2:55 p.m.

CWG snowfall forecast, first issued Saturday at 2:55 p.m.

Tomorrow (St. Patrick’s Day): It’s not an official holiday, but might some of us get another bonus day off? The snow should begin to let up after around 5 a.m. By that point, though, there’s probably enough on the ground to mess up the commute and cause some delays and cancellations. Lighter snow through around 9 a.m. may still add some accumulation. After 9 a.m. or so, enough of that warm March sun should make it through mostly cloudy skies to steadily improve road conditions, even as temperatures struggle toward highs in the low-to-mid 30s with winds near 10 mph from the northeast. Occasional light snow showers may linger through around noon, but with little or no additional accumulation expected. Confidence: Medium

Snow Potential Index

A daily assessment of the potential for at least ~1″ of snow in the next week, on a 0-10 scale. More info

8 (↑) All signs point to a ‘white’ wake-up Monday morning, and likely enough stuff for some delays at least.

Tomorrow night: Skies are partly to mostly cloudy and our low temperatures drop back into the 20s. Confidence: Medium-High

A LOOK AHEAD

Tuesday is a major question mark as some models bring a second significant storm up the coast, while others show a glancing blow or a miss out to sea. The former could mean mostly rain Tuesday into Tuesday night, but we might see some mixed precipitation especially north and west of D.C. Highs should reach the upper 30s to mid-40s with Tuesday night lows in the low-to-mid 30s. Confidence: Low

Our unsettled weather continues into Wednesday.  Moist winds from the southeast and a small disturbance keep the threat for some rain showers and generally damp conditions in the forecast. They also keep our temperatures in check, likely stuck in the 40s to near 50 for highs. Confidence: Low-Medium

Dan Stillman contributed to this forecast.

(Forecast prepared overnight)

Also on Capital Weather Gang

Sunday night snow: Holding firm with 1-4" forecast for immediate area