Dreams of White Christmas not so far-fetched now as snow chance pops into forecast
SEATTLE -- There is generally a 7 percent chance of a White Christmas in Seattle in any given year (defined as 1" of snow on the ground.)
But for snow fans, 2017's holiday now has a chance to beat the odds because there is growing evidence of at least the potential for some light snow around Christmas Eve and/or Christmas Day in the lowlands. But before I continue typing and you go wax up the sleds, the uncertainty remains very high and confidence remains very low.
A weak to moderate weather system will move inland somewhere along the northern half of the West Coast, and depending on the track, may interact with the cold air in place for some lowland snow.
But forecast models have been incredibly inconsistent will all facets of the system. Timing of precipitation arrival ranges anywhere from Sunday morning to Monday morning; amount of moisture ranges from not much to a moderate amount, which depends on the track, which has ranged from staying off shore to the Oregon-Washington border to Northern California. The track will also influence if any warm air is pulled up ahead of the system (keeping it rain) or behind the system (changing initial snow to rain) or if the storm just stays south and we stay snow throughout.
That previous paragraph was to highlight just how uncertain the forecast remains, and thus our confidence in giving much for details is quite low.
The National Weather Service is suggesting that while any spot could see snow in some of the scenarios that could pan out, the best bets are from Seattle north to (and beyond) the Canadian border, the Olympic Peninsula, the North Coast and the Cascade foothills. It's too early to speculate on potential snowfall totals but of the forecast models that have been tossing out snow forecasts, none have shown major amounts. And just to reiterate -- plain rain or even a totally dry day are still viable scenarios.
Whatever falls should taper off later Monday night or maybe Tuesday morning.
First White Christmas in 9 Years?
IF we do manage to get 1" of snow on Christmas Day at Sea-Tac Airport, it would qualfiy as the first White Christmas in Seattle since 2008.
Weather data shows only 5 Christmases in Seattle have had 1+ inch of snow on the ground since 1894 -- 4 inches in 1965 and 2008 and 1 inch in 1909, 1924 and 1990.
Although snowfall data is missing from 1996 through 2007. The most snow to fall on Christmas Day was 1.8 inches in 1909 and 1.0 inches fell in 1965. Six other Christmases have less than 1" of snow fall with 9 other dates measuring a Trace. However, that is just for Sea-Tac Airport; many outlying areas have had more frequent Christmas snowfalls.