I sure hope you had a chance to enjoy Tuesday and Wednesday with the afternoon temperatures in the low 70s. You won’t see 70 degrees for a while. Hopefully we get one in October before winter arrives.
A large, upper-level trough of low pressure will slide down the B.C. Coast and set up shop over the Pacific Northwest. Surges of moist, cold air will be dropping into the trough from the north. As I said here the other day, it is difficult to get a ton of rain out of this pattern but instability showers could set up somewhere.
The Cascades will get several inches of snow, mainly in the higher ski areas and Cascade passes. However, road surfaces are rather warm, so sticking snow on the passes would take continuous snowfall, and this pattern is more of a showery situation.
I will warn those who live outside the central metro area, especially, to be prepared for a good frost Sunday and Monday night. Even here at city levels, it can drop into the mid to upper 30s if we get totally clear nights.
Keep checking the latest weather forecast and conditions as we get into the weekend, and either cover up sensitive plants such as tomatoes or harvest them. They will freeze. Some of this cold air will be coming not only from Alaska and Canada but from the far Yukon territory.
Fortunately, as is often the case, the coldest air slides into Montana, where they are forecasting two or three feet of snow in their mountains with valley temperatures dropping into the 20s for possible snow there, as well.
This is not an historic event but surely not too common for late September. I believe we’ll struggle to reach 60 degrees over the weekend with highs in the upper 50s. It may be a good time to prepare your dwelling and yard for winter.
We will chat on Sunday, hopefully with sunny conditions and not too much wind.