* Winter storm warning for the entire area 4 p.m. Saturday to 6 p.m. Sunday *

4:30 p.m.: NEW forecast posted

Follow the link below for our latest forecast and storm coverage, which will be updated every hour or two this evening:

PM Update: Snow increases this evening and continues well into Sunday. Heavy amounts possible, especially south of Washington

2:15 p.m.: Snow amount forecast increased. ‘Significant’ winter storm expected.

As the first flakes begin in a few spots, the snow forecasts are still growing. We’re bumping our predicted snow totals up another inch or so across the board. We now anticipate four to eight inches in much of the immediate area and five to 10 inches just to the south. The National Weather Service calls for six to eight inches in the District and eight to 12 inches in our southern areas and has expanded the winter storm warning to the Mason Dixon line.


1:45 p.m. forecast update. (Capital Weather Gang)

With the latest data continuing to pour in, and much of it looking rather snowy, it seems prudent to increase this to a Category 3 or “significant winter storm” on our 1 to 5 winter storm impact scale. This means widespread challenging travel conditions are likely tonight through Sunday night. And, because snow is likely to linger into Sunday night, we expect delays and cancellations on Monday morning.


As mentioned in our previous update (below), we expect snow to begin late this afternoon to early this evening from west to east . Patchy light snow and flurries are possible this afternoon, which should not accumulate, before the steadier snow moves in.

Short-term models suggest a localized band of moderate to heavy snow could develop in the region this evening with lighter snow surrounding it. Around one to two inches could fall between 6 p.m. and midnight (locally higher amounts are possible). Then, another wave of moderate to heavy snow could move in overnight, especially in our southern areas.

Our next update will come as the main area of snow is moving in later this afternoon, and we’ll post additional updates through the evening.

11:25 a.m. — Recent information suggests a boom is possible

While there are not yet major changes to the impact expected from this storm, it seems the situation continues to trend snowier.

Before getting to that, start time seems perhaps somewhat delayed compared with initial expectations. We should still see snow move in, generally from west to east, in the hours around sunset. We may be talking accumulating snow by around 3 p.m. west, and perhaps as late as 7 p.m. east. Occasional errant flakes are possible prior.

There is some indication that it won’t take long for snow to pick up in intensity once it begins, with some heavier banding potentially forming. Even without that, snow intensity picks up into the night. Conditions are likely to deteriorate fairly quickly after snow begins, given the cold temperatures in place. Do plan on having preparations complete prior to sunset if at all possible.

Recent modeling has continued a trend toward higher snow amounts, and we would lean toward the higher end of the totals presented on our snowfall map. We may update our projections one more time early this afternoon. This has the potential to be a long-duration event, with a risk for some lighter accumulating snow perhaps lasting into Sunday night.

We are continuing to monitor and will update again as we have more.

8 a.m. — Immediate metro area upgraded to winter storm warning

Early this morning, the National Weather Service upgraded the District, Fairfax, Prince George’s, Loudoun and southern Montgomery County to a winter storm warning (from a winter weather advisory). The warning takes effect at 4 p.m. Saturday, when snow should be beginning, until 1 p.m. on Sunday. In this zone, the National Weather Service increased its snowfall prediction from three to five inches to three to six inches, which is consistent with our forecast.


Areas under a winter storm warning and winter weather advisory. (National Weather Service)

Areas to the north of the winter storm warning are under a winter weather advisory from 4 p.m. Saturday to 7 a.m. Sunday and should receive two to five inches or so of snow.

TODAY’S DAILY DIGIT

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

5/10: If you’re a snow-lover like I am, any day with accumulation is a 10. Maybe for some, it’s a zero? Let’s go with the average.

EXPRESS FORECAST

Today: Thickening clouds. Snow developing in the afternoon. Highs: Near 30 to mid-30s (before snow).

Tonight: Snow, may taper somewhat after midnight. Lows: 22-28.

Tomorrow: Morning snow, ending with time. Highs: Near 30 to mid-30s.

View the current weather at The Washington Post headquarters.

FORECAST IN DETAIL

It’s been a while since we’ve seen a sizable snowstorm in the middle of winter. We have to go back to the Blizzard of 2016, in fact. While this isn’t going to rival that in any way, it’s coming at a prime time to take advantage of cold air and, if you like snow, maximize enjoyment. It’ll stay tranquil through the morning today, but snow should increasingly fill the air as we head toward sunset.

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Today (Saturday): It’s a mostly cloudy start, but perhaps just enough to let the light in. (I’ll check the comments to see how the sunrise was.) Clouds thicken through the morning, and snow may start to break out up in the air. The air is dry, so it will take a while for it to saturate, but flakes begin to reach the ground as soon as early afternoon in west and southwest parts of the area, then progress eastward from there. By sunset, most or all of the region should be seeing snow, with perhaps about an inch on the ground in spots south and west, and more like a dusting to a half-inch or so elsewhere. High temperatures in the low to mid 30s fall below freezing as snow begins. Confidence: Medium

Tonight: We’ll continue to see snow during the evening, and it should generally pick up in intensity deeper into the night. It may ease at times as well, but it seems like the heaviest snow of the storm may come in the overnight period. Several inches are likely to pile up through the night, and untreated roads will become snow-covered and slick. Temperatures are mostly in the mid-to-upper 20s. Winds are light. Confidence: Medium

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Tomorrow (Sunday): Shovels and plows seem likely to be busy in the morning. Accumulating snow could continue for a while, with amounts settling into the three-to-six-inch range for much of the local area -- more south and less north. The storm should be tending to wane as we get into midday if not prior, but it could be a slow process to totally shut off. Even once the accumulation stops, some snow should stay in the air during the afternoon as well. Highs are near or below freezing most spots, with a range from near 30 to the mid-30s overall. Confidence: Medium

Tomorrow night: Winds are gustier, and a few snowflakes could linger into the evening. Otherwise, it’s calming down as the storm pulls away. Lows range from the upper teens north and west to the mid- or upper 20s in the city and southeast. Confidence: Medium

A LOOK AHEAD

The storm is out of here by Monday. Some of the upper-level disturbance lingers, though, which may mean a few snow showers, and skies are likely cloudy. We’ll warm up enough to get some melting underway, with highs headed toward 40 or so. Confidence: Medium

Pleasant weather is back for Tuesday. Sunny skies and calm winds team up with temperatures rising to the mid-40s, which should keep the dripping going. Confidence: Medium

SNOW POTENTIAL INDEX

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

9/10 (): This should be our biggest January snow event since 2016. Flakes begin flying late day.

Capital Weather Gang’s Jason Samenow, Dan Stillman, Wes Junker, and Matt Rogers contributed to this post.