As shown below, the western U.S. has been slightly drier than normal during the past two weeks, but we generally don't get much during this period anyway.
But let's look at the latest precipitation forecasts from the UW WRF model. Each is for a 24 hour period.
Except for the coast, most of the region is dry through 5 AM Wednesday.
But then, we get hit by the first system, with moderate precipitation west of the Cascades crest, particularly over the windward slopes (24-h total ending 5 AM Thursday)
Even more during the next 24 hr (ending 5 AM Friday), with eastern WA getting a piece of it.
Looking at a different model (the National Weather Service GFS), the 6 day total shows light to moderate precipitation over the NW, with heavier amounts in BC. Rain seems to be avoiding California, ending abruptly at the northern and eastern borders. I will let you speculate about the water-repellant nature of that state.
The reason for our descent into moisture? The amplification of the upper level wave pattern with a trough over us, but ridging to our east and west (see below).
The eastern part of the country will be toast as a result. The 6-10 day temperature anomaly forecast by the Climate Prediction Center shows cooler than normal over the West, but above-normal temps over the East.
Announcement: Climate Surprise Talk
During the evening of September 28, I will be giving a talk in Seattle at UW's Kane Hall on Climate Surprise: Unexpected Impacts of Global Warming on the Pacific Northwest. This will be a new talk, based on the latest research, that will describe some regional "climate surprises" that may well occur in our region during the next century. This talk is sponsored by CarbonWa and the Audubon Society To find out more or to secure tickets, please go here.
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