The weather pattern along the West coast from Washington state to California is very dull. In general, there is a ridge of high pressure at 500 mb in control.
This high is providing warm temperatures away from the immediate beaches but not excessively hot weather as we had in portions of Southern California late last week and over the weekend. Temperatures will be averaging above normal.
There is a broad and relatively weak, closed low well west of the southern Oregon/northern California coast. While this spins well offshore the next couple of days, it will eventually head east by Friday and the weekend. Models are in agreement on this. What they are not in agreement on is how far south the low will go. The main effect on the weather would be on how much cooler air occurs, especially in central and Southern California. Precipitation is not going to be much, though there could be a mainly afternoon shower or thundershower in a few spots over Oregon, northern California and northern Nevada. Monsoon moisture is not going to be a player.
A rare, very cold storm dropping south from Oregon sets the stage for snow in places that don’t get much snow and plenty of travel problems.
The amount of water in the snowpack in the Sierra is far below normal for even this time of year.
Flooding will be a given, most widespread in the northern half of the state.
This storm will endanger life and property both on the seas and over land in a large area.
A huge storm is expected it impact much of the Bering Sea beginning Friday night