The Washington PostDemocracy Dies in Darkness

Wet snow may sweep through the Washington region Saturday

It may be the first in a wave of winter storms, but uncertainty is high.

American model simulation of snow on Saturday. (

In the past day, computer models have begun advertising the potential for a snow event on Saturday. And it may mark the start of a series of winter storms that streak across the Washington region.

The specifics of how much precipitation might fall Saturday, when it will start and stop, and who will see the most and least, still need to be worked out. Right now, the chance of at least an inch of snow is around 30 percent to 40 percent.

While uncertainty in snowfall amounts is high, the latest runs of both the European and American (GFS) models show potential for some accumulation.

The European model predicts that light rain will develop over the region early Saturday morning and then fairly quickly change to snow. It forecasts several inches before snow tapers off in the afternoon.

The American model forecast (shown at the top of this post) is pretty similar, although the precipitation is a little lighter and arrives slightly later.

The zone of appreciable snowfall for this event may be rather narrow, so small shifts in the storm track could lower the possible amount of snow. The current predicted track from the European and American models, just south of Washington, is close to ideal for maximizing cold air and moisture in our area. If everything comes together, about two to four inches might fall.

But “accumulating snowfall is far from a sure thing,” said Capital Weather Gang’s winter weather expert Wes Junker.

If the disturbance shifts north, it would draw up enough mild air for more rain to fall (the Canadian model shows this scenario). Or, if it shifts south, “we may only get fringed with light snow,” according to Junker.

The uncertainty in the track of the disturbance, and how it affects the snow potential, is shown in this group of simulations from the American modeling system. The primary model forecast from this system is shown at the top of this post, but here are 20 additional simulations from the model, with slight tweaks to the input data:

Several simulations show the potential for up to a few inches, but quite a few also show little or no snow. The average forecast is for around one inch.

Because the cold air will be in limited supply for this event, the snow is likely to be wet, and our colder areas west and north of Washington have the most accumulation potential (unless the storm track shifts south).

Whatever happens with Saturday’s event, Washington will have additional chances to see wintry precipitation in the days that follow.

“The models are also hinting that a second wave of wintry weather may come through Sunday or Sunday night,” Junker said. Like Saturday’s storm, models vary on the track of this system, which will have big implications on the snow potential.

After the possible Sunday system, models show another wintry system streaking into the area late Tuesday night into Wednesday.

“The bottom line is this looks like an active week with multiple chances of seeing wintry weather,” Junker said.