* Winter storm warning for the entire area 4 p.m. Saturday to 6 p.m. Sunday | Washington braces for first significant snow | Snow total reports *

Overview

  • Through 11:30 p.m. Saturday, generally 1.5 to 3 inches of snow had accumulated.
  • Snow will pick up overnight and into Sunday morning, especially in our southern areas, with several additional inches of accumulation possible. Travel will likely be difficult Sunday morning.
  • Snow intensity may decrease some as Sunday morning wears on, but may pick up again in the afternoon before tapering off in the evening.
  • When all is said and done, 4 to 8 inches is most likely in the immediate metro area, with somewhat more south and less north.  Localized amounts to one foot are possible.
  • Unofficial storm name: “Snurlough” - thanks to recommendation from reader Phil Yabut.

Updates

11:30 p.m. -- Snow continues with a lot more to come through Sunday (final evening update)

Widespread totals of 1.5 to 3 inches have accumulated around the region as snow has fallen steadily all evening. It shows no signs of stopping and computer models all suggest it will continue into Sunday morning with several additional inches of accumulation.

The heaviest snow may focus in the predawn to early morning hours Sunday so expect hazardous travel. Snow may ease for a time Sunday morning, especially from Washington and to the north and west. But snow may pick up again Sunday afternoon for a time, before gradually tapering off Sunday evening.

We’re standing by our accumulation forecast for 4 to 8 inches in the immediate metro area, and a little less to the north and more to the south. However, per the 10:20 p.m. update below, we think there is the potential for a localized area of snow approaching a foot.

We’ll be back with a fresh forecast and updates starting at 6 a.m. Sunday and continuing all day.

We welcome you to keep the storm discussion going overnight in the comment area. Have a great night! - Jason, CWG

10:20 p.m. -- Winter weather expert: ‘someone ... will probably get a foot’

Wes Junker, Capital Weather Gang’s winter weather expert, said the high-altitude disturbance coming through on Sunday is in prime position to maximize snowfall somewhere in the region. “[T]he track would argue that someone in the area will probably get a foot,” he said in an email.

It’s impossible to say exactly where, but when a robust disturbance like this passes through, localized heavy bands of snow set up. Based on the forecast track, the most likely zone would be between the District and Fredericksburg and Southern Maryland. We’ll be watching this carefully.

Note our forecast is still for a general 4 to 8 inches for the immediate metro area and 5 to 10 inches just to the south. But Junker is pointing to the possibility of a localized jackpot exceeding these numbers.

Here are a few more nice photos:

9:35 p.m. -- Heaviest snow of storm so far inside Beltway. Forecast for 4 to 8 inches on track.

The snow this evening has generally fallen steadily and gently. That’s changing some now. A heavier band is pushing inside the Beltway which will make driving for next hour or so challenging. Between around 11 p.m. and 1 a.m., we may see the snow ease a bit as the first phase of the storm winds down.

But after around 1 a.m., the snow should start to pick up from south to north as we begin the second phase of the storm. This should last through the morning to midday hours. Then the snow may ease again between late morning and early afternoon.

During the late afternoon and early evening Sunday, there may be one final wave of snow that pushes through associated with the high altitude disturbance associated with the storm. This could add a topping to whatever falls earlier.

Here’s a simulation of the storm through its conclusion from the HRRR model:


HRRR model simulated radar through Sunday evening. (PivotalWeather.com/PivotalWeather.com)

The bottom line is that our forecast for 4 to 8 inches (maybe a bit more in our southern areas) is still on track and may be conservative. This storm still has another 18 to 24 hours to go.

8:15 p.m. -- Snow totals mounting as radar fills in. One inch in many areas.

While not heavy, the snow is slow and steady, and starting to stack up. We now have many reports of around an inch across the region with a range of around 0.5 to 1.5 inches.

Earlier, radar showed a gap in the snowfall southwest of Washington, but that has since filled in and light to moderate snow is falling pretty much everywhere. This should continue to be the case for the next few hours and, by midnight, most places should have 2 inches or so.

Road conditions continue to get worse so please take it slow if you have to be out. Better yet, stay in.

6:50 p.m. -- Road conditions deteriorating as snow intensity picks up

For the past several hours snow had been mostly light but now it is falling at faster clip. Road conditions are worsening as a result.

Radar shows a moderate band of snow passing over the Beltway at the moment. The snow does ease somewhat to the southwest and the its intensity may lessen for a time later this evening. But then it should pick back up as the night wears on.

So far, most areas have seen a heavy coating. Here are a couple images showing some local roads and the snow building up:

5:30 p.m. -- Snow is here and it’s sticking

The storm arrived on time late this afternoon, and from everything we’re seeing from our readers, the snow is sticking to grass and even the roads all over the metro. As of 5:30 p.m., roads are wet but not slippery, but the shoulders are coated.

So far the intensity has been spotty, varying between flurries and what we’d call “moderate snow showers,” but there’s a swath of heavier snow moving north into the immediate metro now that will probably bring the road temperatures down enough to allow it to stick. If you’re out tonight, take care to drive slow.

Detailed forecast

Snow which began late this afternoon will increase this evening and conditions will gradually go downhill. The first phase of the storm, through around midnight, will put down about one to inches.

The second phase of the storm will take shape overnight into Sunday morning, when the developing low pressure system will be close enough to generate moderate to heavy snow overnight into Sunday morning, when the bulk of the accumulation should occur - adding several inches on top of this evening’s snow.

The storm will start to push out to sea by Sunday afternoon, but a continuing unstable atmosphere around the region may allow snow of varying intensity to continue into the evening.

Through Tonight: Light snow overspreads the area into the early evening hours. Accumulations should be mostly light into the early evening. Snowfall is likely to pick up in intensity as the evening wears on. For those with evening plans, expect around one to two inches by midnight but some locally higher amounts cannot be ruled out. Untreated roads and surfaces will really start to get slippery.

Snowfall rates will pick up in the overnight hours, especially in our southern areas, with an additional 1 to 3 inches likely to fall between midnight and 6 a.m. on Sunday morning. Lows will hover in the mid-to-upper 20s, with winds light out of the northeast at 5-10 mph.

View the current weather at The Washington Post.


4:00pm forecast update (CWG/CWG)

Tomorrow (Sunday): Travel is likely to be hazardous as light to moderate snow continues on Sunday morning. Pockets of some heavy snowfall‚ especially south and east of DC, are possible. Snowfall rates should slowly start to taper off during the afternoon, though it’s likely that we continue to see patchy areas of snow persist into the evening.

Expect up to a few inches of additional snow accumulation through mid-afternoon, with only a dusting to an inch expected into the evening (although we may need to fine tune these amounts). Highs will range from the low to mid-30s with winds from the northeast at 10 mph.

Spotty snow showers eventually shut off completely before midnight Sunday, leaving us with an overcast and cold overnight period. Aided somewhat by the new snow cover, lows will fall into the low-to-mid 20s with winds out of the north at 5-10 mph.

See Ian Livingston’s forecast through next week. And if you haven’t already, join us on Facebook and follow us on Twitter and Instagram. For related traffic news, check out Gridlock.


Snow began in the late afternoon Saturday on Wisconsin Ave., in Georgetown. (Mark Livingstone/Mark Livingstone)

Why the boom potential? Forecast snow totals have steadily increased over the past 24 hours, as has the possibility that some locations may end up in the “boom” range of our snowfall totals map displayed above. The reason has to do with a meteorological phenomenon called frontogenesis.

Later tonight, as the coastal low starts to develop, conditions within our lower atmosphere will align in such a way as to maximize the precipitation rate in what we often refer to as snow bands. It’s always very hard to predict where these bands of intense snowfall will set up, but it’s clear that they are going to set up somewhere, and exactly where that happens could be make a huge difference in snowfall amounts over a short distance.

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