10:34pm Update from Meteorologist Dave Hovde:
The new forecast range for rainfall is getting more refined. Models all day have suggested the higher-end looks less likely. We were using a wide range from light to 1", now it looks like the high side should be .50".
The latest modeling also looks to back up the timing a bit to later afternoon arrival of rain for most.
The system looks to spin right over the area with more activity outside of the Central Coast, also looks more cold than wet. This is disappointing coming off the driest Jan.-Feb 2-month period on record. That period erased early-season surplus rainfall and now the region is in a shortage for the 2021-22 rain season.
This week the Central Coast has already seen some record highs fall including one in Santa Maria yesterday which had stood since 1910. Now, we are forecasting highs that will fall into the 50s by Saturday with rain and snow potential during the transition.
March 1st is the meteorological first day of spring but the system on the way Thursday PM into Saturday is definitely a winter-style system.
The large ridge of high pressure over The West is collapsing, and the trough on the way is cold and will also spin up a low-pressure center over the Central Coast later Thursday into early Friday which will be the peak of the storm.
The first thing you are likely to notice is a surge of low clouds and fog overnight into Thursday morning. Commuters may want to note that. Otherwise much of Thursday will just be a surge of clouds behind W-SW winds 15-20mph.
Rainfall with isolated thunderstorms is possible into early Friday afternoon before the first impulse wanes.
However, a second shot of cold air and upper air energy rolls on Saturday. While additional rainfall should be light Saturday the cold air is very cold and highs look to be in the 50s.
With the air being THIS cold snow levels drop from 5500 down to 4000ft and at high elevations not only is snow likely but there is heavy snow potential, up to 10" with the best chance of the highest snowfall in the Los Angeles County mountains but perhaps 4-6" at the high peaks of Santa Barbara County mountains. Winds will also be up to 35mph so a winter storm watch is also in effect. Snow levels do drop to 2,000ft. by Friday night in some areas.
Additionally, waves will grow as some energy from the North Pacific moves to the Central Coast.
Winds out of the SW on Thursday will help fuel the system but NW Friday into Saturday will help deliver the cold air destabilizing the system.
Sunday into next week looks quiet and temps start a rebound.
The latest mid-range modeling looks quiet into the 3rd week of March.
Earlier this week I reported on the season rain shortages, this system looks to be significant but not a drought buster especially considering the quiet weather anticipated after this storm departs.