Bad news for people in Seattle who were hoping for a White Christmas. The latest information shows that it's likely to be warmer than usual during the holiday.
Normally, there's less than a 10% chance of having a White Christmas in Seattle. This year, the chances seem even lower because the weather patterns indicate that it might not get cold enough for significant snow.
To have snow around Christmas, we need strong and cold high pressure in Canada, east of the Cascades. If this cold air can move east of the Cascade passes and down the Fraser River valley in British Columbia, we also need some moisture from the Pacific.
The early forecasts suggest that temperatures in Canada and east of the Cascades will be warmer than usual this Christmas. Long-term weather models predict temperatures near or somewhat above average for the region. Normally, high temperatures are in the mid-40s, and morning lows are in the 30s.
However, early data indicates that daytime highs around the holiday might be closer to 50 degrees, with morning lows in the upper 30s or lower 40s.
Not only is it unlikely to have very cold Canadian air during the holidays, but the Pacific waters are also warmer than usual. Being close to warmer water means that the overall temperature is likely to be a bit warmer than average.
It's important to note that long-term outlooks are not definite forecasts, and things could change. If you're hoping for a White Christmas, you might have to go to the mountains to see snow this holiday season.
Looking back, the snowiest Christmas Day in Sea-Tac (where Seattle's weather records are kept) was in 1909, with 1.8 inches of snow.
Here's a list of the snowfall on Christmas Day in Sea-Tac:
1909: 1.8 inches
1915: 0.4 inches
1944: 0.2 inches
1965: 1.0 inches
1990: 0.8 inches
2007: 0.9 inches
2008: 0.4 inches
2017: 1.6 inches
