When we arrive within about 72 hours of a weather event, powerful high-resolution tools will be available, and these can be very important given the complex topography of our area. Let me tell you what these tools are telling us.
The Super Rainshadow
The atmospheric river has now made landfall west of Washington, and rain has spread eastward across the region. A heavy rain streak is expected on the latest radar image, with essentially dry conditions over much of Kitsap County east of the Olympics (see below).
The latest super-high resolution forecast for rainfall over the next 72 hours (below), shows a distinct rain streak, with less than 0.5 inches northeast of the Olympics, while up to 10 inches found on the mountains. And east of Washington having super rain action, there will be almost no rain around Yakima.
And if you like the sound of wind in the trees, there’s a lot going on tonight and tomorrow morning, with an extreme north-south pressure difference forecast at 11 a.m. Friday. Southeast winds are forecast to pick up 20-30 mph everywhere and over 40 mph along the coast, over Puget Sound and through NW Washington.
Trees will lose branches and some trees may fall during this early blow, so be careful out there.
Finally, the cold/snow situation is becoming more apparent. The fact that we will get much colder, with much lower than normal temperatures pretty much guaranteed from Sunday onwards.
This is an unusual (out of the ordinary) forecast for the 24 hours ending at 10 a.m. Tuesday.
Much of British Columbia and Montana will have MORE THAN THREE DEGREE below normal. Much of Washington and Oregon will be 10 degrees below normal and beyond.
I’ll take the sweater out of the closet. And cities will have to do what they can to protect the homeless. Yesterday I saw one individual on the Burke Gilman trail shirtless, with several others sleeping on benches or in the woods near the trail.
And then there’s snow. The mountains will be buried in a blanket of white snow – several feet – as shown by the total number of predictions until 4 p.m. Monday from a relatively low resolution forecast (12 km grid distance). .
Looks like the western lowlands are going to have some debris, but I need more work around to get this resolved…and I’ll get to that tomorrow.
But there are two areas at greatest threat. Then on Sunday and Monday, cold air will push out of the Fraser Valley into NW Washington, increasing the chance of snowfall from Bellingham into the San Juans. Some snow will fall northeast of the Olympics as the Fraser current is forced to rise. And a Puget Sound converging region could form around Seattle creating a band of snow over the Midrange (suggested in the image above).
More tomorrow and this Saturday.
