Rain and snow look to return to NorCal over the weekend with the best chances on Sunday

March 11, 2020 – Dry and warm to end the week. Cooler weather with rain and snow chances during the weekend.

Discussion

Clear skies cover most of the region early this morning, with partly to mostly cloudy skies and a few light showers from about the Stockton area southward as moisture continues to pivot around the low centered just off the central California coast. Current temperatures are considerably milder compared to 24 hours ago across the Central Valley, and cooler over the mountains. Readings generally range from the mid to upper 20s in the colder mountain valleys to the mid 50s to lower 60s across the Central Valley.

The deep closed low is forecast to wobble near the central California coast today before heading into SoCal on Thursday, and kicking out to the east on Friday. We`ll continue to see some light precipitation, wrapping around the low, across the southern end of the forecast area this morning, then scattered showers will develop this afternoon across the northern Sierra (mainly to the south of Lake Tahoe).

Short-wave ridging builds over the area on Thursday and Friday resulting in dry and mild weather across the entire forecast area.

Latest operational runs of the GFS/ECMWF continue to trend close to the ensemble average indicating the next deep upper low will drop southward along coast over the weekend. This system will begin to spread precipitation chances southward late Friday night and Saturday and will have the potential to bring significant snowfall accumulation to the mountains above 2500-3500 ft.

Extended discussion (Sunday through Wednesday)

Cold upper low slowly slides down the West Coast over the weekend bringing a threat of widespread precipitation to interior NorCal. Significant snow expected in the mountains of Western Plumas county and the Northern Sierra Nevada. Snow levels lower into the upper foothills by Sunday morning. Will need to monitor forecast instabilities and thus thunderstorm potential as 5H temps progged around in the -30 to -34 Deg C Sunday.

Low continues to influence our weather early next week as it slowly digs off the CA coast with multiple vorticity maxima rotating around it. This will keep unsettled weather in the forecast with below normal daytime temperatures. Drier weather expected Wednesday with daytime temps warming to near to slightly above normal.