Weekend snow forecast still uncertain

The next shoe to drop will be the development of another coastal low, the latest in a series this autumn that are typical of our weather during an El Nino winter. The Pacific Ocean phenomenon sends the sub-tropical jet stream across the lower portion of the continent, grabbing plenty of moisture from the Pacific, then the Gulf of Mexico and the Atlantic and packing it into storm systems that skirt the Gulf Coast, and then come marching up the East Coast.

(New Orleans is having a record-wet December - 22 inches! BWI has already topped 4 inches for the month, and nearly 52 for the year. The 1.41 inches of rain that fell on Dec. 9 set a new record for the date, breaking the old mark of 1.08 inches, set in 1991.)

When those storms reach the mid-Atlantic during an arctic outbreak, the resulting precipitation can mean snow. And sometimes it means lots of snow.

But as we're told every winter, everything depends on how cold the air in place is, and where the storm's center actually goes. And at this point, forecasters and their models remain somewhat uncertain about the storm track. The map above shows where the highest Sunday snow probabilities are, for now, in the forecast model ensemble.

Forecasters are beginning to lean toward a path that moves the storm's center off the coast sooner, rather than later. Here's some of today's discussion from Sterling. Brackets are my translations of weather-ese:

And from an earlier NWS discussion: "The cold air that will be reinforced for the latter half of this week will be ample throughout the column for snow across much of the area, and a mix closer to the bay, Southern Maryland and adjacent areas overnight Saturday and into early Sunday. This activity will be forced off the mid-Atlantic coast into the late morning, early afternoon hours."

We'll just have to wait and see how far inland the snow reaches. Officially, Sterling is rating our snow chances at 30 percent. The forecast low for Sunday morning at BWI is 26 degrees. The Sunday high is 37.

AccuWeather.com offers two possible scenarios for the weekend. Both bring us some snow, but one (map above) brings a more "substantial" storm, smack-dab on the I-95 corridor. But their snow blogger, Henry Margusity, seems to have some doubts about the impact of this storm. He does drop a hint about a Christmas storm, however.

Here's Mr. Foot's offering on the weekend snow.