Friday, February 1, 2008

Almost cold enough...but not quite

There is another chance of snow for the lowlands (including the city of Seattle) for Saturday. A low pressure will be moving southeast out of the Pacific and likely moving south of us Saturday night (see top panel in Figure). This is generally a good setup for snow for the lowlands because it allows moisture to come in from the Pacific and cold air to filter in from the interior over western WA. HOWEVER, the temperatures are not looking quite cold enough for snow down to sea level, and most of the moisture may stay south of the area, leaving only a marginal chance of lowland snow at best.

The bottom panel shows the probabilites for freezing temperatures and the probability for precipitation Saturday night using a combination of the forecast models. Using that and other information, here is the forecast:

Saturday...Mostly cloudy with showers likely. High temperatures around 41. Chance of precipitation 70%. Snow levels around 500 feet. Chance of snow at sea level less than 20%.

Saturday night...Mostly cloudy with scattered showers. Lows around 34. Showers may mix with snow at times, especially on the higher hill tops. Chance of snow at sea level 20%.