February 27, 2020 – Dry with above normal daytime temperatures through Friday. Cooler and breezy this weekend with a threat of showers, mainly in the foothills and mountains. Dry and warmer early next week with breezy north to east wind.
Discussion
Strong upper ridging continues over the area today with well above normal max temperatures. Highs today forecast near record levels again, with KSAC (Record 76) and KSCK (Record 77) likely to set new records. Some locally gusty northeasterly wind possible this morning through favorably oriented canyons and over ridges of the eastern foothills and mountains.
Ridge progresses Friday as Pacific frontal system approaches the PacNW. Lower latitude closed low currently near 25N 136W also progresses under increasing westerly flow. Associated mid to high level cloudiness spreads into the CWA from the SW Friday. High temperatures remain above normal tomorrow, with near record to record levels at some of our southern locations.
Frontal system tracks into the PacNW Friday night into early Saturday, then secondary short wave trough digs offshore near 130W Saturday. Increased dynamic/orographic forcing over the Shasta mountains by the afternoon could result in some scattered light showers. Significant cooling expected Saturday with locally breezy conditions. High temperatures are forecast 10 to 15 degrees lower than Friday.
Associated upper low then progged to dig south through the CWA Saturday night and Sunday. CAA continues over the area Sunday with breezy conditions. Potential for some showers over Interior NorCal Sunday, but with PWs generally around half an inch or less, best chances will be over the foothills and mountains. Snow levels lower into the foothills Sunday, but little to no accumulations expected at those elevations. Bulk of snow will fall over the higher elevations of Western Plumas mountains and Sierra Nevada. 2 to 5 inches of snow is possible at pass levels Sunday with locally up to about 8 inches over the higher elevations of the Sierra Nevada, south of Highway 50. Storm total QPF for the Central Valley only looks to be a few hundredths attm.
Extended Discussion (Monday through Thursday)
Dry and mild conditions are expected next week as the trough exits the region and the Eastern Pacific ridge rebuilds. Periods of gusty north to east winds are expected through mid-week. Regarding temperatures, highs in the Valley will be in the upper 60s to mid 70s, with mountain locations in the low 40s to low 60s. These temperatures are forecast to be 5 to 10 degrees above average for early March.