April showers; dry end to the month?

The synoptic situation will become increasingly active over the next few days over CA and the western United States. This past weekend’s system brought some wetting rains to much of the state and some scattered thunderstorms to a few select locations, but the overall hydrological contribution to the watersheds and reservoirs was minimal to nonexistent. A somewhat stronger system will impact the entire state during the Thursday-Saturday period. The surface low associated with the system will drag a cold front over much of CA late on Thursday and usher in cold air aloft on Friday for some numerous showers and scattered thunderstorms. Coastal areas north of Santa Cruz could see up to a half inch of rainfall, and isolated locations may receive locally heavy downpours under thunderstorms as far south as San Diego County. This system will also bring up to a foot of new snow to the Sierras–something that is desperately needed there this spring. Given the magnitude of the cold air aloft (-2 to -3 C at 850 mb in NorCal), some strong to severe thunderstorm activity is likely in the Central Valley on Friday. After the Friday activity winds down (though it may linger into Sat. in SoCal), another weak system will move into NorCal later in the weekend, possibly producing some light rain totals of 0.25 in. or less. Next week will probably see a return to warmer and drier weather, so we need all the rain we can get in the next few days. It’s going to be a long, dry summer…