White Christmas Odds Improve For Puget Sound: Snow Forecast

SEATTLE — The first day of winter, and the shortest day of the year, arrives Tuesday, and the first measurable lowland snow of the season may not be far behind, according to the latest forecasts. Many in Puget Sound got a small preview of what lies ahead Monday morning, and temperatures failed to escape the mid-30s even by the afternoon.

The next three days should run slightly "warmer," with afternoon temperatures from the low-to-high 40s before things take a colder turn just in time for the Christmas weekend. Forecasters with the National Weather Service's Seattle office flagged a growing potential for snow in a briefing Monday morning, placing early odds at 86 percent for the greater Seattle area to have at least a little on the ground by Christmas Day.

Expanding on the snow forecast Monday afternoon, NWS Seattle posted detailed probabilities for Seattle, Bellingham, Olympia, Aberdeen and Port Angeles, showing the Emerald City all but certain to pick up more than an inch of snow between Christmas Eve and next Monday, along with very promising odds that 72-hour snow totals could even top four inches.

Forecasters said no single day in the stretch stood out as the snowiest, but any precipitation over the holiday weekend is likely to fall as snow.

While specifics on accumulation are difficult to predict this many days in advance, the Seattle Weather Blog notes that at least one model calls for two or more inches of snow by Christmas morning.

The promising snow outlook is thanks to a colder weather pattern expected to set up shop across the Pacific Northwest late in the week, plunging temperatures 10 to 15 degrees below normal over the long holiday weekend. Afternoon highs for the day after Christmas are forecast right at the freezing mark around Seattle, with overnight temperatures in the high 20s.

"Plenty of uncertainty remains regarding how fast cold air is expected to filter into the region at this time, however the forecast trends will bear watching over the next several days," the National Weather Service wrote Monday. "With cooler temperatures, snow levels will be lower, and this could open the door for more wintry precipitation for the lowlands. "

Here is the five-day weather outlook for the Seattle area:

• Tuesday: 44°/42° (PM rain)
• Wednesday: 48°/39° (Rain)
• Thursday: 43°/37° (Rain, PM rain/snow)
• Christmas Eve: 41°/33° (Rain/snow)
• Christmas Day: 37°/28° (Snow)

In the near term, Puget Sound can expect more rain through mid-week, with afternoon highs in the mid-40s. Wind gusts could add to the chill Tuesday night into Wednesday, with peak gusts between 20 and 30 mph around Seattle and Tacoma.

More details on the timing, probability and amount of snow to expect over the holiday weekend will be shared in the coming days.