From my SLO Weathercaster:
An impressive (549-dm) upper-level low pressure system iforecast to move over the Central Coast tonight. This system is currently producing a few scattered rain showers this morning, however, convective showers will become heavier by tonight.

This system will draw cold air from the upper levels of the atmosphere and create an unstable atmosphere with the a possibility of thunderstorms this afternoon through tonight.
These thunderstorms can create gusty winds, hail and periods of heavy rainfall. Total rainfall amounts are expected to range between a quarter and three quarters of an inch.
However, if your location is near a thunderstorm, higher amounts of precipitation could develop.

Today’s maximum temperatures will range from the high 50s to the low 60s. Snow levels are expected to drop to near 4,500 feet in the Sierra Nevada and Tehachapi Mountains with up to nine inches of new snow above 5,000 feet.