Colder-than-average weather today continues to lay the groundwork for the arrival of some wintry weather this weekend, and again toward the middle and end of next week, forcasters say.
None of it seems likely to amount to much, although it may be an annoyance. And there remains considerable confusion and uncertainty among the long-range models as they try to sort out what's in store for next week.
But for the moment, the forecasters out at Sterling are calling for more cold temperatures today and tomorrow - 5 to 10 degrees below the long-term averages for BWI. That means a high today only around 40 degrees. The average for this date at BWI-Marshall is 49. Nightime lows will drop into the 20s.
The cold is the result of Canadian high pressure, which has arrived with clear skies and lots of radiational cooling at night. The high will hang around through most of Saturday, and temps will stick in the upper 30s.
But by Saturday night, the high will be moving off the east coast, making way for somewhat warmer, wetter air in the return flow in the clockwise circulation around the back side of the high.
Then the first storm moves in from the Great Lakes. We'll see clouds first, then the first shot at some snow after sunset, if the forecast holds up. Overnight lows on Saturday/Sunday will drop below freezing at BWI. Southern Maryland is more likely to see rain. But in the higher elevations it will be snow, forecasters say in this morning's discussion from Sterling.
"However, there is a chance for light snowfall accumulations to occur further east of the mountains, including the Baltimore Washington metro area," they said. They're rating the chance for snow here at 50 percent Saturday night and 20 percent Sunday.
Sunday looks cloudy at first, with highs hanging in the upper 30s. Then colder air will move in with gusty winds. Skies will begin to clear and temperatures will drop Sunday night into the low 20s. If you're going to the stadium, dress for winter.
Monday's highs will hold in the mid-30s, more than 10 degrees below the average for the date.
Looking ahead into next week, the forecasters see model projections all over the place. Here's AccuWeather.com's blogger Henry Margusity's foggy crystal ball. Most of the models seem to be predicting two storms - one in the Tuesday/Wednesday time frame, the second late in the week. The folks at Sterling say "Storm A" is most likely going to bring Baltimore some rain.
"However, with the first wave, if precipitation moves into the [forecast area] late Monday night into Tuesday morning, then a wintry mix of snow, sleet and freezing rain may be possible at the onset before the bulk of the precipitation would turn to rain," their morning discussion says. The chance for precip is set at 60 percent.
As for "Storm B," they're saying, "If this wave tracks south of the area, some wintry precipitation may be possible. ... Needless to say, details will need to be resolved/fine tuned with time as we move closer to the middle of next week."
The big picture seems to be that while there is nothing especially notable about any of this, December does seem to be shaping up as a relatively cold and wet start for this winter's weather. And that is pretty much what the seasonal forecasters said during the fall: wintry December, giving way to a milder January, then shifting back to more wintry experience sometime in February.