Chance of showers over the weekend into next week, mainly over the mountains and Northern Sacramento Valley. Below normal high temperatures through next Thursday.
Discussion
Longwave troughing off the West Coast with embedded channel vort maxes will move across northern portions of CA today as associated cold front drops into NorCal. This will bring a threat of light showers mainly north of I-80 and over higher terrain with snow levels around 4500 to 5500 feet. Some breezy southerly wind today expected today in the Northern and Central Sacramento Valley. Below normal high temperatures forecast today with mid 50 to mid 60s for the Central Valley.
Troughing continues to deepen Sunday into Monday as colder shortwave from the GOA drops into the longwave. This will result in more widespread threat of showers with best chances in the foothills and mountains. Snow levels Sunday lower to around 2500 to 3000 feet in the Shasta mountains and 3500 to 5000 feet in the Southern Cascades and Northern Sierra. Snow levels lower into the foothills Sunday night into Monday.
Some instability depicted over Shasta and Tehama counties tomorrow afternoon for possible thunderstorms. Areas of breezy wind possible tomorrow and Monday afternoon. WPC Snow totals for the Sunday/Monday timeframe look to be around 2 to 6 inches above 4000 feet with local amounts up to 8 to 10 inches over higher terrain of the Sierra Nevada.
Longwave troughing progresses into the Great Basin Tuesday. Weak impulses down the back side of the trough will keep a slight chance of showers over the mountains, north of I-80 Tuesday into early Wednesday but any additional snow accumulations will be light. Below normal high temperatures continue Tuesday into Wednesday with areas of morning frost possible in the Central Valley.
Extended Discussion (Wednesday through Saturday)
Long wave trough forecast to finally shift east by the middle of next week as ridging moves over NorCal by the end of the week. Some showers may linger over the mountains until about Thursday.
Temperatures are forecast to finally return to about average by next weekend.