The past few weeks have been generally warmer than normal, but that will soon change, replaced by at least one cool week, with temperatures dropping below normal through mid-month.
Here’s a look at some of the forecast. In Seattle, temperatures will reach the upper 80s today and Friday before dropping to the mid-70s Sunday through next weekend.
Temperatures in Pasco, in the Columbia Basin, will rise to near 100 degrees Fahrenheit, before dropping to the upper 80s next week.
What’s going on?
The higher level chart (at 500 hPa…about 18,000 ft) shows the change.
Last night, there was a large high pressure ridge (high pressure ridge) over northwestern Canada and part of this feature extended south across the West Coast (red indicates higher than normal altitude/pressure, blue indicates lower than normal pressure).
By Tuesday, the picture was very different: Canada’s great ridge was gone, replaced by a trough of low pressure, with a trough stretching across the Northwest. The ridge brought sinking, warm air, the trough the opposite.
There could even be some light rain, with enough accumulation through Wednesday morning to dampen western WA and southern BC
Cooling with some light drizzle in some places will be enough to significantly reduce the wildfire threat, as shown by the NW Coordination Center’s ERC (red is threat, blue is less risk)
