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.
A rather intense, cold, wet trough moves through California Friday into Saturday morning.
I have been faced this week with a classic dilema that all meteorologist face from time to time
A large portion of the West should have a good look at the lunar eclipse later Monday night.
this winter will go down as least snowy in over a decade
A storm west of the northern California/Oregon border will bring some more spring rain and thunderstorms with mountain snow into Wednesday.
A series of storms continue their onslaught on about an every other day time frame through the end of next week.