Winter storm arriving Tuesday
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. Precipitation amounts are expected to be small but it will be a wild day of weather. Temperatures will dip with highs in the 50ss. Lows into the 30s. Winter weather advisory in place for all mountain areas from 6AM Tuesday through noon Wednesday. Dry weather is expected Thursday through the weekend with a warming trend.
The upper-level trough will continue to sink south into California tonight through Tuesday morning. A slight chance of rain showers will develop across San Luis Obispo and northern Santa Barbara Counties by Tuesday morning then become more likely and spread southward in the afternoon and evening. The bulk of the precipitation is expected late Tuesday into early Wednesday. The air mass is originating from Canada so this will be a cold system with low snow levels. At precipitation onset snow levels will start out around 3500-4000 feet, then crash down to 2000 feet or locally lower by early Wednesday morning. Since this system is taking a mainly continental track, there is very limited moisture to work with. As for our area, have continued with previous thinking of a range of a tenth to quarter inch across the board. Locally higher amounts up to a half inch are possible in places that see thunderstorm activity. Due to a rain shadow effect from northwest flow aloft, southern Santa Barbara County and southern Ventura County will likely receive the least amounts, less than a tenth of an inch. Snowfall totals of around 1 to 3 inches are likely over 3000 feet. With snow levels so low, icy conditions and light snow accumulations are a concern for the major mountain roads. Some of these roads include a large portion of Interstate 5 corridor from the Grapevine to Castaic, Highways 14 and 138 in Antelope Valley and Soledad Canyon, Highway 33 in Ventura County mountains, Highway 154 north of San Marcos Pass, Highway 166 through Cuyama Valley, and several highways across interior San Luis Obispo county. Winter Weather Advisories will be in effect from 6am Tuesday through noon Wednesday. Additionally, light accumulations are also possible for the Antelope and Cuyama Valley foothills, and even a dusting to an inch for the valley floors. Winter Weather Advisories for these valleys starting 4pm Tuesday also through noon Wednesday. Also, a slight chance of thunderstorms will be possible Tuesday night with ample vorticity advection and cold unstable air aloft. Other items of note for the storm will be gusty winds and cold temperatures.
Wind Advisories have been issued for Ventura coasts and valleys from 8am to 6pm Tuesday. Breezy winds are also likely for the Central Coast but likely below advisory level. Wind advisory for Santa Barbara South Coast and mountains from 6 Monday night until 6 Wednesday morning.
Wednesday, more importantly will be the cold overnight lows. Interior areas will see temperatures in the low 20s and closer to the coast 30s will be common by early Thursday morning. Frost headlines may be needed for some areas. By Wednesday night precipitation will cease across the area and Thursday will be dry and sunny. Temperatures will rebound a little but still remain cool with highs in the low 60s.
The trough will pass to the east and surface high pressure will develop across the Great Basin. This will bring a return to breezy northeast winds and warm things up as we head into the weekend.
