* Winter weather advisory Sunday night for northern Fauquier and western Loudoun counties in Virginia and northern Montgomery and western Howard counties in Maryland | Winter storm warning for northern Md. (and to the north and west) | Snowfall totals from National Weather Service *

Key points

  • Precipitation should taper off between midnight and 1 a.m. Watch out for slick spots overnight as temperatures drop into the upper 20s and low 30s.
  • For most of the area, the snowfall was either a bust or at the low-end of our forecasts. Amounts generally ranged from a trace in the immediate area to 1 to 4 inches in Frederick County.
  • Sunshine returns Monday, but it’s cold and breezy, with highs 35 to 40.

Updates

10:50 p.m. - This event will soon conclude and, for snowfall, it was basically a bust

Radar shows the back edge of the precipitation in Frederick and Loudoun counties and it will gradually push east and exit the region over the next couple of hours. It’s not out of the question that some areas seeing rain now see some snow and sleet mix back in before the precipitation ends but no accumulation is expected.

After the precipitation exits, temperatures will slowly drop a few degrees into the upper 20s (north and west of the Beltway) and low 30s (around town) which mean wet and slushy spots could turn a little ice, especially in our normally colder locations.

Snowfall totals are still preliminary, but here’s a rather unimpressive sampling:

  • Reagan National and Dulles: Trace
  • BWI: 0.2 inches
  • Purcellville: 0.4 inches
  • Columbia: 0.6 inches
  • Damascus: 0.8 inches
  • Thurmont: 3.5 inches

Sunshine is back for Monday but it’s breezy and cold, with highs only 35 to 40.

This is our last update for this event. Have a great night.

9:15 p.m. - Mixed precipitation and snow causing slick conditions in our north and northwest areas

While it’s just a cold rainy night in the immediate metro area, it has become snowy and, in spots, icy in our far north and northwest suburbs. The rain-snow line continues to straddle western Loudoun and southern Frederick County, which is seeing a wintry mix of snow, sleet and freezing rain. But some pockets of mixed precipitation are also showing up in central Loudoun and northern Montgomery counties.

Accumulating snow continues falling in northern Maryland, including around Frederick.

We’re now into the final leg of this storm and the rain-snow line may try to work east in the next few hours before precipitation shuts off. This may allow some mix and snow to slip back into the immediate area but it will be brief and probably won’t amount to much if anything.

The zones to look out for slick spots on roads and sidewalks are mostly north and west of the yellow line on this map where temperatures are around and below freezing:


Temperatures around 9:15 p.m. on Sunday night. (Weather Underground)

7:20 p.m. - A cold rain in the immediate area, but a pasty snow in parts of northern Maryland

A cold rain is falling in much of the immediate area but wet snow, heavy at times, is coming down in northern Maryland.

The snow is coating roads around Frederick and Interstate 81 near Winchester is reportedly covered in two to three inches of snow. Hagerstown also has about two to three inches of snow.

Several inches could now pile up in Carroll and Frederick counties in northern Maryland before the snow tapers off around midnight.

The divide between rain, sleet, and snow seems to run through western Loudoun and southern Frederick County. This line may try to gradually push east in the next few hours which would allow parts of central and western Loudoun County and northern Montgomery County, which had changed to sleet and rain, to see a transition back to more snow and sleet.

5:25 p.m. - Winter storm warnings and winter weather advisories scaled back


(National Weather Service)

As snowfall and mixed precipitation have generally been less than expected, the National Weather Service changed the winter storm warning to a winter weather advisory in western Loudoun, northern Montgomery and western Howard counties. In these areas, total snowfall is now projected to be 1 to 3 inches. Some slick spots from snow and wintry mix are still possible here.

The Weather Service discontinued winter weather advisories in eastern Loudoun, southern Montgomery, and eastern Howard counties, where snow has changed to sleet and rain - and temperatures are mostly above freezing. Roads in this area are expected to remain wet.

A winter storm warning remains in effect for Frederick counties and the others in northern Maryland adjacent to the Mason Dixon line. Here snowfall totals of at least a few inches are still anticipated.

3:40 p.m. - Rain-snow line setting up north of the District. Mostly a non-event from the Beltway south.

After seeing a rain-snow mix in parts of the District and nearby areas for a time this afternoon, precipitation has mostly changed to rain and sleet and it seems like the snow line has set up just to the north.

While we can’t rule out some snow mixing in at times, it seems like this is a mostly sleet and rain event moving forward for the Beltway region and points south, with minimal impact.

Even where it’s snowing to the north, most of the accumulation is on grassy areas. This, however, could change in the next hour or two as daylight wanes and temperatures settle near freezing. In Loudoun, northern Montgomery, western Howard and Frederick counties, some slick spots are possible on untreated surfaces through early evening.

Generally, the areas where we might see some slick spots develop are north and west of the yellow line on this map showing temperatures:


Temperatures at 3:40 p.m. on Sunday. (Weather Underground)

But these same areas which see snow over next few hours are projected to change to sleet and then rain later this evening (from south to north between 5 and 10 p.m.) as temperatures warm a bit several thousand feet into the atmosphere. The exception to this may be in northern Maryland near the Pennsylvania border where it may stay cold enough for snow or a snow/sleet mix.

Across the board, based on how this event is evolving, we think snowfall totals will probably end up on the lower side of earlier projections.

1:45 p.m. - Precipitation becoming steadier. Rainy around Beltway, but wet snow to west and northwest

Radar and reports indicate mostly a cold rain around the Beltway but we’re seeing some of the patchy light rain change to snow in our colder areas as the air cools a bit. In general, the coverage and intensity of the precipitation has increased and that should continue through the afternoon.

Most of the snow falling, so far, is melting on contact with temperatures well above freezing (35 to 40) in the immediate areas.

However, out toward Interstate 81 and northern Maryland, temperatures drop to 32 and 35, and snow is beginning to accumulate, especially on grassy areas.

It looks like for the next few hours the rain-snow line should set up right around the Beltway, with more snow north and west and rain south and east. Inside the Beltway, precipitation types may mix and alternate. As the precipitation intensifies, the air will cool a few more degrees, which should allow some slushy accumulation - mainly on the grassy areas in our immediate north and west suburbs but some slick spots will become possible as you head further west toward Interstate 81 and Interstate 70.

12:10 p.m. — Light snow and rain for now, steadier midafternoon into evening

Occasional light snow (north) and rain (south) will continue to move through the area, with a steadier wintry mix that is likely midafternoon into evening. Current temperatures, as shown below, tell the story of why we don’t expect much impact on the roads across most of the immediate D.C. metro area. They’re in the upper 30s to low 40s right now, and even with a possible burst of heavier precipitation late afternoon into evening, will probably only dip to the mid-30s. Whereas our farther northern and northwestern zones could drop a little closer to freezing, thus the bigger concern there for slick spots.


Temperatures as of about noon on Sunday. (Weather Underground)

10:40 a.m. — Slight changes to accumulation map, otherwise forecast on track

After a review of the latest model data, we’ve tweaked our forecast map one last time:

  • Slightly lowered the low end of what was one to two inches across Northwest Washington and the immediate north and west suburbs to coating to two inches because, when the heaviest burst of precipitation comes through this evening, it could be more rain or sleet than snow in this zone. We continue to expect most accumulation in this zone to be on grass.
  • Slightly lowered the low end of what was two to four inches across the northern parts of Loudoun, Montgomery and Howard counties to one to four inches for the same reason as above. The wider range also reflects the likelihood of the rain/snow line setting up in this zone late afternoon into early evening, which means snow amounts could increase quickly from south to north over a relatively short distance, with the higher terrain in the northern part of this zone having the best chance of higher amounts.
  • We also increased the bust percentage in our far north three- to six-inch and four- to seven-inch zones due to the chance of more sleet mixing in with the snow there.

See below for our updated map. Otherwise, our detailed forecast below seems on track. The main takeaway from all this still looks like little to no snow/sleet accumulation on roads for most of the immediate metro area, but some slick spots possible as you head north and west of the Beltway late this afternoon and evening, and more significant snow and sleet accumulation well north and northwest of the District such as in Frederick and Carroll counties in Maryland.


CAPITAL WEATHER GANG/THE WASHINGTON POST (CWG/CWG)

Original forecast from 6 a.m.

TODAY’S DAILY DIGIT

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

2/10: The morning’s not too bad, but the afternoon and evening’s sloppy mess is best enjoyed through the windows.

EXPRESS FORECAST

Today: Wintry mix midday and afternoon. Highs: Mid-30s to near 40.

Tonight: Evening wintry mix, tapering overnight. Lows: Upper 20s to low 30s.

Tomorrow: Partly sunny, a bit breezy. Highs: Upper 30s to low 40s.

View the current weather at The Washington Post headquarters.

FORECAST IN DETAIL

Someone forgot to tell Mama Nature about that “meteorological spring” thing. Today brings a tricky winter storm that features conditions ranging from accumulating snow and sleet to cold rain over a relatively short distance from north to south across the area. The end result, we believe, is not much wintry impact on the roads in the immediate metro area, but an increasing chance of slick spots heading north and west of the Beltway. After the storm, winter digs in with temperatures well below normal through midweek.

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Today (Sunday): Patchy light snow or rain could develop later this morning but with little consequence as temperatures hover in the mid-30s to near 40. Steadier snow or sleet becomes likely during the afternoon, with some rain mixed in from Washington toward the south and east. Inside the Beltway and to the south and east, temperatures in the mid-30s should limit any impact to roads, with a light accumulation possible mainly on grass. Our closer-in north and west suburbs including Fairfax, Montgomery, Howard, and eastern Loudoun counties could see a thicker coating on grass, but still with little to no road impact expected.

Farther north and northwest, we could see around one to three inches of snow in Frederick, Carroll, and northern Loudoun counties with slick spots possible by late afternoon as readings fall into the low 30s. Confidence: Low-Medium

Tonight: Most of the immediate area and points south and east should flip to a cold rain as we get into the evening. But snow or sleet should continue from the northern parts of Loudoun, Montgomery, and Howard counties toward points north and west including Frederick and Carroll counties, with potential for an additional one to three inches, and slick spots possible with temperatures in the low 30s. Precipitation should taper everywhere after midnight with overnight lows in the upper 20s to low 30s. Confidence: Low-Medium

Follow us on Facebook, Twitter, and Instagram for the latest updates. For related traffic news, check out Gridlock. Keep reading for the forecast through midweek.

Tomorrow (Monday): With no hard freeze overnight, we don’t expect widespread icy conditions for the Monday morning commute. But some slick spots and school delays are possible, mainly north and west of the District. Otherwise, we’ll see winds kick up from the northwest, with some gusts near 25 mph. Temperatures are held in check despite skies becoming partly sunny, with highs in the upper 30s to low 40s. Confidence: Medium-High

Tomorrow night: We’re headed for a much colder night, with calming winds and partly cloudy skies. Overnight lows drop into the upper teens and low 20s. Confidence: Medium-High

A LOOK AHEAD

Looking out the window, Tuesday might seem like a fairly nice day. In some respects, it will be, with mostly sunny skies and light winds. It’s just that our temperatures run well below normal, only topping out in the mid- to upper 30s. You can’t win 'em all. Overnight, it’s back to brrrrrr territory, as lows drop all the way back into the teens under mostly clear skies. Thank heavens for whoever invented heated seats. Confidence: Medium-High

We’ve reached the peak of this early-March cold snap by Wednesday. Many spots may struggle to reach freezing, with highs only in the upper 20s to low 30s. Even on a partly to mostly sunny day in March. Yowza! Winds from the northwest could turn a bit gusty as well, making it feel more like the teens and 20s. Just what we needed. Confidence: Medium-High

SNOW POTENTIAL INDEX

A daily assessment of the potential for at least one inch of snow in the next week, on a zero to 10 scale.

5/10 (): Decent chance of an inch or so of snow in parts of the are Sunday late afternoon into evening, even if it’s more on grass than anything else.ng tDuring the evenin