Tuesday night will remain windy with heavy rain and snow in the passes overnight, but the rain is expected to quickly end Wednesday morning starting a week of calmer and drier weather. A much colder weather pattern is expected to arrive late next week.
It’s a textbook atmospheric river scenario over the next 24 hours across Washington and Oregon as a fetch of very moist air from north of Hawaii funnels into the region. This moisture is being wrung out by our terrain and nearly nonstop rain will fall through Tuesday.
The wettest first half of January on record was 6.91″ for Seattle in 1956. Coming into this morning we were at 5.12″, but with the unofficial and running total, we are already in the top five wettest starts to January!
As rain continues to fall throughout Tuesday another 1-3″ will fall in the lowlands and more than 4″ in the Olympics and near Mount Rainier. This will spike our rivers higher, including the Snoqualmie and Skokomish which are predicted to reach moderate flood stage by Wednesday. Other rivers will reach minor flood stage. This river flooding is similar to or slightly worse than what we experienced weekend before last. Urban flooding will be a problem where storm drains clog up and the danger is especially pronounced at night when drivers can unknowingly drive into high water.
In the mountains it has been and will continue to be very interesting! Low level offshore wind has kept the passes cold enough for snow and so far, we’ve had nearly 20″ at Snoqualmie and nearly a foot at Stevens. Stevens is still seeing snow Tuesday evening, but snow levels are rising. Snoqualmie is warming up as well.
We are in a relative lull in the rain and wind for the next couple hours, but after about 9 p.m., winds will start to ramp up at the coast and by around 11 p.m., it will get windy around the Sound. Most locations will have wind gusts over 30 mph and there is increasing chance for wind gusts to commonly hit 40 mph, particularly near water and on hilltops. Winds could be even stronger north/west of Everett and at the coast. There aren’t any wind warnings or advisories by the National Weather Service, but we could still have spotty power outages this evening and overnight with wind gusts of that magnitude.
Wind and rain will diminish rather quickly on Wednesday morning and it looks like we could have some sun by Wednesday afternoon. Thursday will be dry with a mix of clouds and sun after some morning fog. Some light rain will be around Friday ahead of a pretty dry weekend. I am putting in a slight chance for rain on the holiday Monday but it could be rather dry then too.
Long-range outlooks point to a colder weather pattern setting up near and after Inauguration Day. While this doesn’t guarantee a shot at lowland snow, having the overall colder-air regime in place helps those chances toward late January into early next month.
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