Ice phase of storm begins as snow tapers (LIVE UPDATES)

December 8, 2013

** For Sunday morning to Monday morning: Winter Storm Warning west of the District | Winter Weather Advisory for District and points east **


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.

Overview: This afternoon, snow gradually transitions from snow to sleet and freezing rain from south to north, but additional accumulation is possible – with totals generally 0.5-2″ in the immediate metro region, but progressively heavier amounts north and west of the Beltway. 3-6″ is likely from western Montgomery county to Leesburg, with isolated 6″+ totals possible to the north and west. Significant icing is possible overnight, especially west of I-95.

Related: Storm timeline, amounts, SchoolCast, other impacts and FAQs | Live game updates | The Grid: Tweets, Instagrams from today’s snow | Maryland pavement temperatures | Snowfall reports

5:45 p.m. Update: This is the last update in this post. For continuing live updates on the storm, please follow this link: Winter storm warnings extended east; lull in heavier activity until late evening (LIVE UPDATES)

5:22 p.m. Update: It’s dark and icy out there, and despite a break in the precipitation now moving in from the west, freezing rain is expected to pick up quite a bit later this evening and overnight. The National Weather Service has upped its ice forecast to upward of 0.25″ from D.C. and I-95 toward points west. Count on delays and cancellations tomorrow in the yellow and pink areas of the map below. We’ll have our updated SchoolCast shortly.

5:09 p.m. Update: D.C.-Baltimore area airports are doing their best to keep operating despite the accumulating ice. Here are recent updates from Reagan National (in a ground stop until 5:30pm at last report), Dulles and BWI

 

 

 

4:48 p.m. Update: WPVI in Philadelphia is reporting 1 dead in an accident on the Pennsylvania Turnpike that may have involved up to 50 vehicles. See story here.

4:30 p.m. Update: In the update below we show a model graphic depicting quite a bit freezing rain between 10 p.m. and 4 a.m. It’s also worth noting that both models and radar suggest we’ll see a decent lull in precipitation from around 6-9 p.m., though many roads will remain quite slick and hazardous without the benefit of daylight. 4:07 p.m. update: Frequent question: How long is this supposed to last? Most of the night. Freezing rain and sleet should transition to mostly just freezing rain as the evening wears on. Then, between 1 a.m. and 7 a.m., freezing rain may change to plain rain from east to west. Though the intensity of the precipitation may wax and wane, the NAM model still simulates quite a bit overnight. (And radar shows a big wave of precipitation entering Tennessee that will stream northeastward)


The NAM model simulates between 0.5-0.75″ of precipitation between 10 p.m. Sunday and 4 a.m. Monday. At 4 a.m. Monday, the freezing line is simulated just west of I-95 (StormVistaWxModels.com)

Bottom line it’s going to back slick into the pre-dawn hours, at least. Transportation officials in the District warned motorists, even those driving SUVs, to slow down, especially on the District’s bridges. “Ice is the great equalizer for us all. It doesn’t matter if you have a 4×4,” said Reggie Sanders, communications director for the District’s Department of Transportation. “If you’re going to slide, you’re going to slide on four wheels. We want people to slow down.” The Post’s Ann Marimow contributed to this report. 3:55 p.m. update: With darkness approaching, slushy spots will gradually start to turn quite icy – even though temperatures should hold more or less steady.


3:44 p.m. update: The National Weather Service has crowd-sourced snowfall reports from spotters on the map below. The bulls-eye – where 4 to 8 inches were common – focused in Frederick, northern Carroll and northern Baltimore counties as well as around Winchester. (Note: Although not shown on the map, both Reagan and Dulles airports reported an inch of snow) See the text list: Snowfall reports 3:20 p.m. update: Radar shows moderate band of freezing rain and sleet moving into the D.C. area. At 3 p.m. both Reagan National and Dulles Airports reported freezing rain, with temperatures of 31 and 28, respectively. 3:07 p.m. update:


2:56 p.m. update: Cause for concern: Maryland road pavement temperatures are sub-freezing throughout the entire region – generally in the 20s. This underscores the risk for icy travel into this evening. 2:35 p.m. update: Since the snow phase of this storm is basically over, now is a good time to remind everyone what we expect in terms of ice. Here’s our ice accumulation map:

Temperature Map

Temperatures: Latest D.C. area temperature map. See interactive map on our Weather Wall.

 

 

Right now, we have a mix of sleet and some freezing rain in the area and temperatures should hold more or less steady into the early evening, at least. Around the region, most of us are between 25 and 30 degrees F. As the amount of daylight decreases and frozen precipitation continues, untreated roads are likely to freeze and become hazardous.

2:20 p.m. update: With snow having changed to sleet in many areas now, the bulk of the snow part of this storm over. Check out these impressive snowfall pictures (and totals) north and northwest of the District:

2:05 p.m. update: Via Cindy Boren on her blog The Early Lead: Snow games steal the show in NFL 1:55 p.m. update: We’re seeing a rapid transition from snow to sleet from southeast to northwest across the region now, as a pocket of warm air above 5,000 feet is partially melting falling snowflakes, which are then refreezing before hitting the ground (as sleet, aka ice pellets). If you’re getting sleet now, most of your snow accumulation is likely over.

In Calvert County, CWG’s Wes Junker reports: “I’m now sleet and freezing rain at 28.5 degrees.”


1:43 p.m. update: The National Weather Service has again increased its snowfall accumulation forecast. The revised map looks good – although it may still be conservative in a few areas in northern Maryland and northwest Va, which have already received 4-8 inches of snow (although – as noted below – we think the heavy stuff is about to wind down). Howard Bernstein at WUSA-TV9 has also increased his snowfall projection.

1:33 p.m. update: CWG’s Jeff Halverson posted a useful comment below, worth putting up here: “This current heavy batch of precip may ease up a bit toward mid-afternoon. The rapid, intense arrival of snow was generated by an upper-level wave that is moving through the region. Once we get on the back side of the wave, the dynamic uplift should wane for a while. But all the other elements for sleet and ice through the evening remain in place – including the cold wedge and increasingly warming air around 5,000 ft.”

1:25 p.m. update: As of 1 p.m., both Reagan National and Dulles airports had picked up 1″.

1:20 p.m. update: Totals are continuing to mount north and northwest of the Beltway with 3″ reported in Germantown and Damascus, 6″ in Mt. Airy, 5″ in Martinsburg. But in Fairfax County and to the south and east, 1″ or less has fallen.

 

 

 

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Dan Stillman · December 8, 2013