Pacific storm moves through over the weekend with rain in the lower elevations, gusty wind, and mountain snow impacting travel. Isolated thunderstorms possible Sunday. Drier weather expected for most of next week.

Thunderstorms possible. Most likely timeframe: tonight – Sunday. Impacts: lightning. Small hail. Brief heavy rain. Gusty winds. A map on the right shows an area of thunderstorm chances for the Sacramento Valley & Northern San Joaquin Valley up into the Sierra foothills and an area along the California coast from the Oregon border through Marin County.

Discussion

Current forecast remains on track. Precipitation will start to spread into the interior valley this afternoon and mountains late this afternoon and early evening. Snow levels expected around 5500-6500 feet this evening, ahead of front, lowering to 3500 to 4000 feet Sunday. Moderate to Heavy snow is forecast tonight for the west slopes of the Sierra with 1 to 3 feet on new snow over the higher elevations.

Snow forecast. Map on the left shows snow amounts for mountain locations across interior northern California. Snow amounts generally range from 1 to 3 feet above 5000 feet, 3 to 15 inches above 4000 feet. Impacts: major. Travel delays and possible road closures. Chain controls. Reduced visibility due to gusty winds and blowing snow. Snow levels: 5000 – 6500 ft Saturday night, lowering to 3500 – 4500 ft Sunday. Timing: Saturday evening - Sunday, February 4-5, 2023.

As the cold front moves into the region instability will increase with the models favoring the southern half of the CWA for best potential for any thunderstorms.

Breezy to locally windy conditions are likely this evening into the early morning hours as the front moves through. The front will have passed by Sunday morning so there may be a break in the rain for the valley to start the day with showers likely continuing over the western slopes.

Wind forecast. A map on the left shows the wind gust forecast with gusts up to 25 to 40 mph over the Central Valley and foothills and up to 40 to 60 mph over the mountains. Impacts: moderate. Secure outdoor items. Local downed tree branches. Difficult driving conditions at times. Timing: Saturday night – Sunday morning. Hide Caption

Cold core upper low will move over the area on Sunday. This will help to increase instability for showers and thunderstorms during the day. Currently profiles suggest small hail and heavy rain with any thunderstorms and continues to favor the southern half of the CWA.

Rain Forecast. Map on the left shows precipitation amounts for interior northern California. Amounts range from 0.25 to 1 inches in the Valley and from 0.50 to 2.5 inches across foothills and mountains. Impacts: Minor. Longer than normal travel time and ponding of water on roadways. Thunderstorms. Snow levels: 5500–6500 ft Saturday evening, lowering to 3500–4500 ft Sunday. Timing: Late this afternoon - Sunday, February 4-5, 2023.

As the low moves southeast of the area Sunday evening activity will die off. Storm total precipitation is generally below an inch for the Central Valley, and 1 to 3 inches for the foothills and mountains.

Drier weather returns early next week with some locally breezy north to east wind Monday and Monday night, chilly nights, and near normal high temperatures.

EXTENDED DISCUSSION (Wednesday THROUGH Saturday)

High pressure will be over the region during the extended period. Dry with warmer than seasonal normal daytime temperatures and cool nights expected.

Breezy conditions may occur on Wednesday and Wednesday night behind a weak shortwave passing by to the north of the region.

Fog potential should be low on Wednesday but increase in the valley by Friday. Currently the deterministic models favor keeping the area dry into the first part of next weekend with a closed low to the west of the coast. Clusters however want to bring a trough over the region for next Saturday. Light chances for precipitation for now with a lot of uncertainty still that far out.