A potential storm system will stall over the Central Coast Tuesday night, spreading across the area later Wednesday. Several inches of rain are likely with flooding concerns including recent burn areas. A couple feet of high elevation mountain snow is also expected, along with moderate to strong south winds. Much quieter weather expected over the weekend into early Monday.
A low pressure system, currently parking itself off the Oregon coast will move little through Thursday, this will create a steady and nearly persistent stream of moist southwest flow (known as an atmospheric river) focused over San Luis Obispo and Santa Barbara counties starting Tuesday night and lasting through at least Thursday with 2 to 3 days of nearly constant rain. Sitting on the fringes of the plume, Ventura County will see several hours of rain during that time. All areas will see moderate rain Thursday with lingering showers into Friday as the system swings through California. Things should taper off by Friday afternoon or night.
With such a long period of steady rain, San Luis Obispo and Santa Barbara counties are in store for a copious amount of rain. Expecting 3 to 6 inches of rain, with 8 to 10 inches likely in the foothills especially near the Santa Lucia range. For Ventura County, 1.5 to 3.5 inches are expected, and 2 to 5 inches in the foothills and mountains. With these types of amounts, expect peak rain rates between 0.25 and 0.75 inches per hour. San Luis Obispo County and other favored southwest facing foothills could see three hour rates between 1.00 and 2.00 inches. All of this will result in roadway and creek flooding, especially over coastal San Luis Obispo County where a flash flood watch is in place from 3AM Wednesday through 10PM Thursday. Thunderstorms are possible on Thursday for the tail end of the storm. Showers expected to continue into Friday.
Snow levels will generally be between 5000 to 6000 foot range, except closer to 4500 feet tonight and Thursday night into Friday. Mountains above 6000 feet should expect 1-3' of snow, depending on how long they are in the moisture plume. Winter Storm Warning in place for Santa Barbara & Ventura counties mountains 3AM Wednesday trough 3AM Friday.
Gusty winds have prompted warnings and advisories for San Luis Obispo county and Santa Barbara coast and valleys until 4PM Thursday.
Temperatures will stay chilly with highs in the upper 50s to low 60s.
The weekend looks quiet and cool, except for a few light showers possible north of Santa Barbara. projections are showing a low pressure system possibly moving through Monday or Tuesday, with widespread and mostly light rain. Impacts look minimal at this point, but something to keep an eye on.