Significant snow has fallen all the way down to sea level in most of WA and OR today. Temperatures are dropping in NorCal and showers are beginning to develop along the coast. Extremely cold air aloft will conintue to filter southward as the upper low drops down just inland from the CA coast. This airmass will be quite unstable over CA, but as there is very little moisture available to be condensed in the moist convection process, showers will likely be scattered at best away from the Eureka/Mendocino coastline. These showers will certainly fall as snow above 500-1000 feet if they develop, even during the daytime hours, and any morning or overnight precipitation will be in the form of snow all the way down to sea level in NorCal. A few snowflakes are possible even in San Francisco on Thursday night! SoCal could actually see a few more showers than the Bay Area as there will be some overwater trajectory of the westerly flow rounding the base of the trough. Some snow showers are possible down to 1000 feet near Los Angeles, which could actually impact some suburbs with a dusting of up to an inch. Beyond these rather meager (but still exciting) snow chances are the record-breaking cold temperatures expected Thurs/Fri/Sat nights. Lows in sheltered places in the Bay Area will drop to 20 or below, possibly as low as 15 in the coldest valleys. Temperatures well below 30 degrees are expected even near the coast north of Mendocino. It is possible that one observing station in the Bay Area could see temps approach the single digits, and could have subzero windchills in the next few days. Where could this possibly happen, you ask? On the top of Mt. Hamilton, of course. As of 7 PM on Wednesday, the air temp is 27 degrees, dropping quickly, and the windchill is 15 degrees. That’ll be an interesting one to watch.
Long term: looks very dry, for the most part. A chance exists that a cut off low could develop under or undercut the powerful block that currently exists. Stay tuned, but does not look at all promising for SoCal rain. You will see some more Santa Anas, though…
