Forecast Update from Chief Meteorologist Dave Hovde: The forecast is looking even colder than earlier today which requires a winter weather advisory to be added for the interior and mountains of SLO county. Snow and icy road conditions are expected. Total snow accumulations of a dusting to one inch on the valley floor and 1 to 2 inches in the foothills. Snow levels will start around 2500 feet Tuesday afternoon but drop down to 1500ft (1000 is possible).
You wouldn't know a cold system is on the doorstep looking out your window today. Morning clouds cleared and Monday ended up being a nice day but conditions will change quickly overnight.
A very cold storm system will move through the area Tuesday into Wednesday, bringing a chance of rain and low-elevation snow showers and gusty winds along with a slight chance of thunderstorms with small hail Tuesday night. Behind the system, it will be quite cold Wednesday night as well.
The first opportunities for showers will begin after midnight as the system arrives for the Central Coast. The low-pressure system will linger thru Tuesday and early Wednesday morning before dropping out of the area. On and off scattered showers are likely thru all of Tuesday into early Wednesday morning. Isolated thunderstorms are possible with the cold unstable system which could produce areas of hail.
Rain accumulations look to be somewhat light locally, under .50 and most will likely stay under.25"
Winds will pick up on Tuesday for most of the Central Coast at 15-25mph out of the northwest. For the Santa Barbara Southcoast and higher terrain there is a wind advisory already in place for NW winds 15-25mph gusting to 35mph. The advisory begins at 6pm Monday and expires 6am Wednesday morning.
There is also a winter weather advisory for the Santa Barbara County mountains as low levels drop from 3500ft to 4000ft on Tuesday morning all the way down to 2,000ft by Tuesday night and Wednesday morning. 1-3" of accumulation is likely and some spots in Southern California could see up to 5". The winter weather advisory begins 6am Tuesday and lasts thru noon Wednesday.
After the system departs, a lot of cold air will be left behind. Lows in the interior valleys will be near freezing tonight, in the mid to upper 2-s Tuesday night and lower 20s on Wednesday night into Thursday. The next time interior low will be warmer than freezing will be Sunday night into next Monday. Inland highs will be in the low to mid-50s Tuesday and Wednesday. 60s for Thursday to Saturday and back into the 70s Sunday.
Freezing lows are possible in the coastal valleys Tuesday night into Wednesday but more likely Wednesday night into Thursday. Highs near the coast will be in the 50s the next few days before working back to the 70s by the weekend.
There is some model disagreement over how quickly temps warm after the low kicks out of the region later in the week.