An atmospheric river sets up this week with a direct stream from near Hawaii of warmer, very moist air (a true “pineapple express”) and this is going to keep snow levels in the mountains very high, meaning rain instead of snow all the way to above 8,000 feet in elevation starting Tuesday.
In the lowlands, following some rain mainly north half into tonight, we have several days of soggy weather with 1-2 inches of lowland rain, on average, around the Sound and more at the coast through the end of the week. In the mountains, 4-8 inches of rain will fall.
It will also be breezy at times through midweek with gusts in the 20-30mph range at times, but no extreme winds are expected.
While the lowlands will be able to handle the wet weather this week, the high snow levels in the mountains means a lot of rain on top of fresh, unstable snowpack. Avalanche danger will remain very high this week and the rain combined with some melting snow will bring some rivers like the Tolt and Snoqualmie to minor to moderate flood stage by midweek. Also the Skokomish and Chehalis rivers are forecast to reach minor flood stage this week.
Farther north, flooding impacts will be more likely on the Skagit River on Friday and Saturday as runoff will take longer to impact that river system. Moderate flooding is currently projected on the Skagit to end the work week and begin the weekend.
River forecasts will continue to be modified as rain falls, so there could be some changes to forecast flood stages and times. By no means is this a repeat of December’s atmospheric river flooding, but some impacts are likely in and near the flood plains this week.
We’ll get a break in the rain over the weekend but next week’s weather looks like it could be unsettled once again, but cooler — with a return to lowland rain showers and mountain snow. Spring officially begins at 7:46 am this coming Friday.
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