Mountain snow and Valley rain showers will continue through early Saturday as a weak system impacts the region. A renewed chance for showers returns late Sunday into Monday. Dry weather will return for the middle part of next week before a late week system takes aim on northern California.
Discussion
Radars are back in precipitation mode across northern California this early Saturday morning as a quick-moving system impacts the region. Minor rain and snow amounts have been observed thus far, but do anticipate the peak of the event to occur between now and sunrise. That said, overall precipitation amounts will likely remain on the light side for many communities; locations south of I-80 in the Valley will likely see little or no rainfall. In the mountains, snow levels through mid-day Saturday will range from around 4000 ft in the southern Cascades to around 5000 to 5500 ft in the central Sierra. This is where the main impacts will be as accumulating snows on roadways may cause reduced visibilities and travel delays. Consequently, a Winter Weather Advisory is in effect for Western Plumas County/Lassen Park area at/above 4000 ft through 10 AM PST Saturday, and for the Western Slope of the Sierra Nevada at/above 5500 ft through 12 PM PST Saturday. Total accumulations in the advisory area will be 3 to 7 inches on average with localized amounts near 10 inches. As always, motorists are encouraged to check with CalTrans for the latest road conditions.
High resolution models indicate that the precipitation will end from north to south by mid-morning to early afternoon today. Any lingering afternoon rain/snow showers would likely be confined to the higher elevations. Most populated areas in the Valley can expect a rather tranquil day with a mix of clouds/sunshine and highs within a few degrees from where they should be for this time of year. Normal February 13th highs are 61 deg F for Downtown Sacramento and 59 deg F for Redding.
Upper level ridge will develop over the region for the second half of the weekend, promoting mostly dry conditions. Can’t rule out some patchy radiational morning fog in portions of the southern Sacramento Valley and northern San Joaquin Valley if we get sufficient clearing, but as the nighttime hours continue to decrease as we dive deeper into February, the climatological likelihood for fog similarly decreases.
By the late afternoon/evening hours on Sunday, a shortwave trough will approach far northwestern California and bring with it renewed precipitation chances. Even for Shasta County, much of Sunday should remain dry as the onset of precipitation appears to hold off until the late afternoon or evening timeframe. Light precipitation will gradually spread from north to south overnight and into the day on Monday (Washington’s Birthday holiday).
Valley impacts will remain minimal as rain amounts are expected to remain light while the mountains have the chance to see some travel impacts associated with accumulating snowfall. Early projections indicate snow totals will be on par or perhaps slightly lower than the system that is presently impacting the region. The system will exit the area overnight Monday and into early Tuesday with dry and mild temperatures returning.
Extended discussion (Wednesday through Saturday)
Dry weather with above normal temperatures continue Wednesday under EPAC upper level ridging. Ensemble solutions suggest Pacific frontal system will spread light to moderate precipitation over interior NorCal Thursday with lingering showers, mainly over the mountains, Friday.
Another colder short wave trough progged into the CWA Saturday with continued unsettled weather. Snow levels start out around 3500 to 4500 feet Thursday morning, rising to around 4500 to 6000 feet Friday, then lower to 2500 to 4000 feet Saturday.