D.C. area forecast: Snow to arrive tonight; several inches likely by Thursday morning

** Winter storm warning tonight through Thursday afternoon **

** Winter weather advisory for Calvert and St. Mary’s counties **

5:15 a.m. update: Most overnight model runs (including the European and NAM) still favor a 6-9″ thumping for the immediate metro region, mostly tonight into early Thursday morning, with higher totals toward Dulles where precipitation should remain all snow longer into Thursday. One model’s early morning run (the GFS) was still a bit drier with a 4-6″ range near the city. Our latest CWG forecast (see details and map below) still looks valid.

Today’s Daily Digit

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

6
Yet another chilly day in this very chilly winter, but the feel of snow adds excitement to the air.

Express Forecast

Today: Increasing afternoon clouds. Highs: Upper 20s to near 30.

Tonight: Snow develops during the evening, heavy at times through the night. Lows: Mid-20s.

Tomorrow: Snow, possibly mixing with sleet and rain. Highs: Near 30 to mid-30s.

FORECAST IN DETAIL

While tweaks to the forecast are almost inevitable when it comes to winter weather around here, the general story still looks the same as it has, with several inches of snow likely tonight, before possibly mixing with sleet, freezing rain, and rain during the morning, especially near I-95 and points east. Beyond tomorrow, the pattern looks to remain active, with snow showers possible Friday night, and another system to watch for late Monday into Tuesday. Let’s get to the details as best we can…

Today (Wednesday): After some morning sun, it starts to feel more like snow as clouds increase during the afternoon. We’re plenty cold throughout the day with highs in the upper 20s to near 30. Winds are light from the east-northeast near 5-10 mph. Confidence: High

Tonight: Snow moves in from the south between approximately 7-11 p.m. With a cold ground and temperatures falling into the mid-20s, it should start accumulating almost immediately. The snow is heavy at times, piling up several inches (3-6″) by dawn. Confidence: Medium-High

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

Tomorrow (Thursday): Beginning around 4-5 a.m., snow may mix with or change to sleet from southeast (e.g., Southern Md.) toward the northwest (e.g., Frederick). But the progression may take several hours, and it’s unclear how far north and west of D.C. the sleet will reach. That means areas from around D.C. and I-95 to the east may see their snow accumulation curtailed by sleet, and perhaps even some freezing rain or plain rain, starting early-to-mid morning. While areas west of there may hold on to all or mostly snow. Precipitation likely continues into the afternoon, and may change back to all snow from west to east, ending by early evening. Breezes turn gusty at times from the north-northwest, with highs near 30 (northwest) to the mid-30s (southeast). Confidence: Medium

Below is our latest snow accumulation forecast map. New model runs come out between 9-11 a.m. We’ll be analyzing the data, and will update our forecast as needed.


Capital Weather Gang snowfall forecast, first issued noon, Tuesday, 2/11.

 

Snow Potential Index

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

9+ (↑) Four inches or more a good bet for most tonight into Thursday. Plus a dusting or so possible Friday night.

Tomorrow night: Clearing skies likely move in during the evening and winds diminish overnight. Lows in the 20s are chilly, though not nearly as cold as we’ve seen earlier this winter. Confidence: Medium-High

A LOOK AHEAD

A milder breeze from the west-southwest helps Friday highs to near 40 to the low 40s under partly sunny skies. Another system may come through with snow or rain showers sometime Friday evening into Saturday morning, and could potentially refresh our snow cover with a dusting or so, as overnight lows drop back to the mid-20s to near 30. Confidence: Low-Medium

The rest of the holiday weekend should be mostly quiet weather-wise, save for a few possible flurries on Sunday, with Saturday through Sunday highs in the 30s to near 40, and nighttime lows in the 20s. We do need to watch the progress of yet another system that could spread precipitation our way as soon as late Monday. We should be on the warmer, mostly rain side of this system, but could see it start as a period of mixed precipitation. Confidence: Medium

(Forecast prepared overnight)

Dan Stillman is a meteorologist and editor for the Capital Weather Gang. He earned an M.S. in Meteorology from Texas A&M University, and a B.S. in Atmospheric, Oceanic and Space Sciences from the University of Michigan.
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