Showery weather from cutoffs NorCal; new Santa Ana event SoCal

The impressive-looking subtropical moisture plume that moved over the middle third of CA yesterday brought little to no precipitation to the area–there were a couple of reports of trace amounts  to as much as 0.02 in., but that’s not even enough to wet the ground entirely. The dual upper lows responsible for the deep southerly flow that has entrained all this mid and upper-level moisture will lift NE over the northern half of the state over the next 48 hrs. A rather more impressive subtropical plume has redeveloped on the southeastern side of the smaller and more southerly low, which is poised to come ashore in NorCal later tomorrow. This ample mid-level moisture, along with increasing dynamic instability and steepening lapse rates, will probably allow for some convective development tomorow afternoon over the Bay Area and Central Valley.  A chance of showers and thundestorms will develop from west to east, and will continue until late Tuesday night when the second upper level low has moved on to the east. Shower and thunderstorm chances will be best through the entire event around the Bay Area and the northern half of the Central Valley, but the entire CA coast from Eureka south to about Santa Barbara stands the chance of some raindrops.  SoCal will almost certainly see no rainfall from this system, unless the subtropical plume is deflected more to the east that is currently expected. Halloween should see clearing skies across the state. By the weekend, a new Santa Ana event will probably develop. Although it won’t approach in magnitude the impact of last week’s offshore event, gusts over 50 mph will still be possible along with warmer temps and lower hums. Some of the fires in SoCal remain uncontained and are still threatening homes. If they are still burning by Saturday, we could once again have a serious fire situation in CA. Stay tuned… 

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