Arctic air is spilling into the eastern United States and colder-than-normal weather should stick around for the next two weeks, at least. This cold pattern is setting up to mostly be a dry pattern, with the possible exception of Friday night into Saturday.
Some snowflakes could fly at times between Friday night and Saturday night, and perhaps late Tuesday. But, depending on how storms track, some locations may totally miss out on snow over the next week, despite the cold.
The prospects for snow Friday night and Saturday have always been fuzzy and remain so. A wave of low pressure forecast to develop off the coast may be too weak and too far away from land to throw back much moisture into our region.
However, a few weather models, the UKMet, the NAM and the Canadian, forecast a stronger coastal wave and show the potential for some accumulating snow Friday night into Saturday, especially in our eastern areas.
Others models aren’t so bullish on snow chances. The American GFS model keeps the storm far enough offshore that we wouldn’t see much more than some non-accumulating snow or light rain in our eastern areas. That said, a few simulations of that same model, with input data slightly tweaked, do predict some more significant snow over the D.C. area, especially along and east of Interstate 95 Friday night into Saturday.
The European model, which is most accurate on average, keeps any meaningful precipitation well to Washington’s east.
We’re somewhat skeptical of the forecasts presenting accumulating snowfall in the region, but can’t completely rule out some sneaky snow from this system, especially in our eastern areas.
The most difficult winter weather forecasts are those when our region lies right along the edge of a storm, and this is one of those cases. So we’ll need to carefully monitor model forecasts over the next two days.
If we don’t muster any snow from the coastal wave Friday night into Saturday, the opportunities for accumulating snow become slim.
By Saturday night, a reinforcing shot of cold air is arriving, and a little impulse riding along the jet stream could produce some snow flurries or snow showers, but any accumulating snow is likely to be limited to the mountains.
The other chance of snow we’re watching is from a disturbance forecast to zip through the region next Tuesday into Wednesday. Models show it also being moisture-starved, so it may again be difficult to manage any snow accumulation. Those itching for snow can hold out hope that the disturbance ends up being a little stronger than modeled and that it perhaps draws in some Atlantic moisture — but that seems to be a long shot.
Wes Junker, Capital Weather Gang’s winter weather expert, explained that the problem for snow lovers is that, beyond Saturday, all of the weather systems passing through the region are riding along the northern branch of the jet stream, flowing out of Canada into the eastern United States, and can’t tap into any significant moisture sources.
“It’s a poor pattern for any significant snow,” Junker said. “There’s mainly just a chance of snow flurries with the impulses and cold fronts coming through.”
For more significant snow potential, Junker said, it would require the southern branch of the jet stream to come alive and transport weather disturbances across the southern part of the nation, where they could draw moisture from the Gulf of Mexico and then the Atlantic.
While the pattern beyond Saturday is not good for heavy snow opportunities, it does support a sustained period of cold weather through Dec. 20 at least. But we do not anticipate record-challenging cold. “It’s a cold pattern, but not a brutally cold pattern,” Junker said. “There aren’t big high-pressure areas behind the series of cold fronts to bring us the real Arctic air.”
Model forecasts for the next two weeks call for highs mostly in the upper 30s to low 40s, while average highs are in the upper 40s.
Despite the less-than-stellar pattern for heavy snowfall, the longer it stays cold, the more opportunities we’ll have for one of these passing disturbances coming in from the northwest to give us at least a little bit. These so-called clippers can once in a great while put down a few inches. So we’ll continue to monitor.