More troubling, the snow should quickly change to sleet and freezing rain. As the ground will be frozen solid due to the recent cold, any icy precipitation will likely stick immediately to untreated surfaces. Driving may become hazardous.

The good news is that, as precipitation falls, temperatures will warm from southeast to northwest — eventually above freezing. But they may not warm fast enough to prevent the region from being glazed over for a time.

AD

Models differ in their forecasts for how fast temperatures rise and also in the amount of precipitation.

AD

Confidence in exactly how this event will unfold remains low, and the National Weather Service says the winter storm threat is just slight — for the moment.

The most ominous forecasts hang on to freezing temperatures longest — through midday Saturday — and unload the most precipitation. However, some models predict temperatures may rise above freezing rather quickly and forecast lighter precipitation, reducing the amount of iciness.

At the moment, the Canadian and GFS models present the more threatening ice scenario while the European model forecasts more modest icing before a changeover to plain rain.

The Canadian model

The Canadian model has snow streaking into the region before dawn, with perhaps an inch or so falling. Temperatures hold in the mid-20s.

Then precipitation turns to ice, before tapering off as rain midday as temperatures cross over the freezing mark. Temperatures warm well above freezing from southeast to northwest during the afternoon.

The GFS model

The GFS brings in the precipitation a little later than the Canadian — between 7 and 10 a.m. Saturday, which allows temperatures at high altitudes to warm a bit.

So it forecasts any snow to be brief and inconsequential, except in D.C.’s northern suburbs, before turning to sleet and freezing rain.

Temperatures are forecast to steadily warm Saturday morning from the mid-20s to just above freezing, when the precipitation tapers off as plain rain. A break in the rain is expected during the afternoon as temperatures warm above 40.

The European model

AD

AD

This model has the most benign forecast. It predicts a bit of snow, sleet, and freezing rain to develop between 1 and 4 a.m. Saturday morning — enough to lay down an icy coating in most areas.

However, by 7 a.m., it predicts that temperatures rise above freezing east of Interstate 95. By 10 a.m., freezing temperatures retreat into our far western suburbs.

By midday, temperatures across the entire region are well above freezing.

For most of the area, this model predicts that the heaviest precipitation falls as rain after temperatures have risen above freezing.

In short, it would suggest just a few hours of icy travel in the early morning hours Saturday before rapidly improving conditions by the mid-and-late morning.

AD

Concluding thoughts

It is going to be difficult to escape at least a period of frozen precipitation late Friday night into Saturday morning. But big question marks remain about the intensity and duration of frozen precipitation.

AD

The worst case scenario is a heavy slug of frozen precipitation and temperatures lingering around freezing through midday. The best case scenario is just a brief period of frozen precipitation very early in the day before plain rain takes over.

“It’s too soon to say which scenario is most likely,” said Wes Junker, our winter weather expert.

Although there will be no mechanism for holding in the cold air during the day Saturday, sometimes freezing temperatures are slower to retreat than models predict. So there is some chance iciness lasts a bit longer than we have presented — perhaps into the afternoon — especially in our colder suburbs.

As this winter weather event is still four to five days away, a lot can still change — especially with respect to the event’s specifics.