Gusty north to east winds today. Pacific storms will bring periods of rain, mountain snow, and gusty wind through the week into next weekend. Potential for more flooding and impacts for mountain travelers.
Discussion
Precip winding down over southern portions of the CWA attm as upper troughing digs southward into SoCal and upstream upper ridging begins to build inland. 48 hour QPEs showing rainfall amounts in the Central Valley from around 1 to 5 inches, with 3 to 10 inches in the foothills, and some mountain locations seeing around a foot of rain.
As a result, urban and small stream flooding has occurred with significant rises on mainstream rivers and tributaries. Levee failure has also been reported on the Cosumnes River near Wilton.
In addition to the precip, strong winds were observed earlier tonight in the Southern Sac/Northern San Joaquin Valleys with gusts to 61 mph at KSMF, 64 mph at KSAC, and 54 mph at KSCK.
Snow levels have lowered to around 5500 ft in the Sierra Nevada however precip is winding down. Few lingering snow showers possible over the Sierra Nevada this morning, otherwise drier weather expected for the first day of 2023 over interior NorCal.
Some breezy northerly wind forecast as upper ridging builds inland and surface high builds into OR, but speeds expected to remain generally below advisory criteria. Highs today will be near to slightly below normal.
Break in the wet weather will be short lived as models spread more precip with the next Pacific storm into the area Monday through Monday night.
Light to moderate QPF expected with snow levels around 2000 to 3000 feet. Weak wave moves through Tuesday keeping a threat of some light showers in the forecast.
Another AR forecast to impact NorCal midweek with IVT values up to around 750 kg/ms. More moderate to heavy precipitation possible with potential for more flooding.
Early QPF for the midweek storm looks to be around 1 to 4 inches possible in the Central Valley with 3 to 8 inches or more of liquid precip in the foothills and mountains.
Snow levels start out around 4-5k ft early Wednesday rising to around 5-6k ft by early Thursday with mountain travel impacts expected.
Extended Discussion (Thursday through Sunday)
Wet pattern for NorCal forecast to continue for the end of the week and next weekend as strong westerly flow continues beneath a quasi-stationary low over the Gulf of Alaska. The tail end of another moderate to strong atmospheric river is likely to be moving through on Thursday. This system may bring renewed potential for flooding (it’s still too early to forecast the details and magnitude of any potential).
Snow levels will likely be lower than the current system, so winter travel impacts are looking to be much more significant and prolonged. Ensembles indicate a brief break Friday with another series of wet systems lurking for next weekend into the following week.