


Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
804 FXUS66 KSTO 122016 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 116 PM PDT Mon May 12 2025 For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing. .Discussion... .Synopsis... A weather system will bring chances for light showers, mountain snow showers and isolated thunderstorms through Tuesday. Drier weather will follow with seasonable temperatures and occasionally breezy winds. Isolated showers and thunderstorms possible over the Sierra and southern Cascades Saturday. Gusty northerly winds and low relative humidity may bring elevated fire weather conditions across the Sacramento Valley late weekend into early next week. && .Key Messages... * Today-Tuesday: -Light showers and mountain snow showers continue as a weather system moves through -50-80% probability of rain > 0.25" mainly across northern Sacramento Valley, northern Sierra north of Hwy 50, and adjacent foothills -15-35% probability of isolated thunderstorms today and Tuesday, highest chances across north/central Sacramento Valley, foothills and mountains. Thunderstorm chances on Tuesday will be over the Sierra foothills and mountains. -10-50% probability of 2" snow along the Sierra above 5500 feet, 70-90% probability in the southern Cascades/Lassen Peak * Mid to Late Week: -Dry weather, seasonable temperatures and occasionally breezy winds -Light showers and isolated thunderstorms (10-20% probability) across the Sierra Saturday afternoon and evening. * Sunday - Monday: -Elevated fire weather conditions as gusty northerly winds and low relative humidity overlap in the Sacramento Valley -Probability of gusts 40 mph or higher: 30-50% along and west of I-5 in the Sacramento Valley. Strongest winds on Sunday. .Changes from previous forecast... -Showers and thunderstorm chances possible over the Sierra and southern Cascades Saturday afternoon and evening. && .AVIATION... VFR conditions across all TAF sites next 24 hours. Gusty southerly wind gusts 25-30 kts in the lower elevations, and 30-40 kts gusts over the Sierra out of the southwest until 06z Tuesday. There is a 10-35% chance of isolated thunderstorms across the northern Sacramento Valley, foothills, and mountains until 06z Tuesday and again 18z Tuesday-03z Wednesday over the foothills and Sierra/Southern Cascades, with periods of MVFR conditions. Gusty and erratic winds near thunderstorms. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$