A rather strong upper-level low for the time of year has been dropping south along the Oregon coast today. By tomorrow, it will come to rest in northwestern California where it will sit and spin into Thursday. The water vapor satellite picture below easily shows this low on the Oregon coast and also shows how that low has really dried of much of California and westernmost Arionza.
The low will cause noticeably cooler-than-normal temperatures in California the next two days, especially at the coast and coastal valleys along with the Central Valley as temperatures run 5 to 10 degrees below normal. The low is also likely to cause scattered showers and thunderstorms in parts of Oregon and Washington.
As the low sits in place into Thursday, it will actually snap up the upper-level disturbance from Fabio in the Eastern Pacific. While Fabio itself will not be a factor, the upper-level feature at the very least will carry mid- and upper-level moisture northeast with it, bringing it into southern California late Wednesday into Thursday morning and anytime Thursday in central California. While mostly clouds are likely, it is not impossible that there could be a shower or thundershower in spots with the upper-level feature.
On this move through, the 500 mb high that retreated east will move back to the west Friday through the weekend. This is likely to turn the flow into the southeast bringing monsoon moisture back to the west, entering California by the weekend. This is likely to renew the thunderstorm threat for at least the mountains and deserts again.
With approximately 1.6 million acres burned so far this is about 600,000 acres less than last year
Within the three-state area of Washington, Oregon and Idaho, there are 21 large fire incidents ongoing.
The water level on this massive reservoir had never been lower than what was reached on July 9.
It has been pretty hot of late in the interior Northwest but even hotter weather looks likely by Sunday and Monday.
It does not usually rain this time of year; when it does, this is usually how it happens.
This is the beginnings of the summer monsoon pattern that typically starts around the first week in July.