Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
249 FXUS66 KSTO 030943 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 243 AM PDT Fri May 3 2024 .SYNOPSIS... DRY AND WARM WEATHER TODAY WITH LOCALLY BREEZY NORTHERLY WINDS. ACTIVE WEATHER RETURNS THIS WEEKEND AS A WEATHER SYSTEM DROPS DOWN BRINGING SHOWERS, MOUNTAIN SNOW, ISOLATED THUNDERSTORMS, GUSTY WINDS AND MUCH COOLER TEMPERATURES. && CURRENT GOES-WEST SATELLITE IMAGERY SHOWS GENERALLY CLEAR SKIES ACROSS MUCH OF INTERIOR NORTHERN CALIFORNIA THIS MORNING WITH THE EXCEPTION OF A FEW LOW LEVEL CLOUDS OVER PARTS OF THE MOUNTAINS. TEMPERATURES ARE CURRENTLY IN THE 50S IN THE VALLEY AND FOOTHILLS, AND 30S TO 40S IN THE MOUNTAINS, VALID AT 245 AM PDT. DRY AND WARM WEATHER WILL PREVAIL TODAY, WITH JUST SOME LOCALLY BREEZY NORTHERLY FLOW. ACTIVE WEATHER WILL RETURN TO THE REGION VERY LATE TONIGHT, AS A WEATHER SYSTEM DROPS DOWN FROM THE GULF OF ALASKA BRINGING SHOWERS, MOUNTAIN SNOW, ISOLATED THUNDERSTORMS, GUSTY SOUTHWEST WINDS AND MUCH COOLER TEMPERATURES ON SATURDAY. PRECIPITATION FIRST LOOKS TO ARRIVE TO FAR NORTHWESTERN CALIFORNIA LATE FRIDAY NIGHT, AND SPREADS INLAND SATURDAY. LATEST GUIDANCE FROM WPC SHOWS STORM TOTAL QPF AMOUNTS OF 0.50" TO 1.25" IN THE VALLEY, AND 1" TO 2.25" IN THE FOOTHILLS AND MOUNTAINS. LOCALLY HEAVIER AMOUNTS WOULD BE POSSIBLE WITH ANY THUNDERSTORMS THAT DEVELOP, AND THERE IS A 15-25% PROBABILITY OF THUNDERSTORM DEVELOPMENT ON SATURDAY, WITH BEST CHANCES NORTH OF INTERSTATE 80. PRECIPITATION LOOKS TO TAPER OFF SUNDAY MORNING. A WINTER WEATHER ADVISORY REMAINS IN EFFECT TO ADDRESS THE SNOWFALL IN THE MOUNTAINS FROM SATURDAY INTO EARLY SUNDAY. THE NATIONAL BLEND OF MODELS (NBM) SHOWS A 55-85% PROBABILITY OF 8 INCHES OF SNOW, MAINLY ABOVE 6000 FEET. SNOW LEVELS WILL INITIALLY BE AROUND 6000-8000 FEET, AND WILL LOWER TO AROUND 3500-4500 FEET THROUGH THE DAY SATURDAY, AND THEN DOWN TO 3000-4000 FEET SUNDAY MORNING. PEOPLE SHOULD PLAN AHEAD FOR THE LATE-SEASON WINTER WEATHER, AND CHECK THE FORECAST AND ROAD CONDITIONS BEFORE TRAVELING IN THE MOUNTAINS THIS WEEKEND AS SNOW COVERED ROADS, CHAIN CONTROLS AND TRAVEL DELAYS WILL ALL BE POSSIBLE. GUSTY WINDS WILL ALSO DEVELOP FRIDAY NIGHT THROUGH SATURDAY AS THE STORM APPROACHES AND MOVES THROUGH THE AREA. THE NBM SUGGESTS A 55-85% PROBABILITY OF WIND GUSTS OF 40 MPH OR GREATER, MAINLY IN THE NORTHERN/CENTRAL SACRAMENTO VALLEY AND NORTHEAST FOOTHILLS, AND A 75-95% PROBABILITY IN THE MOUNTAINS. MUCH COOLER TEMPERATURES ARE ALSO EXPECTED AS THIS STORM SYSTEM MOVES IN. HIGHS ON SATURDAY WILL BE ABOUT 15 TO 20 DEGREES BELOW CLIMATOLOGICAL NORMAL FOR THIS TIME OF YEAR, WHICH IS ALSO HIGHLIGHTED IN THE EXTREME FORECAST INDEX (EFI). DRIER CONDITIONS AND SLIGHTLY WARMER TEMPERATURES RETURN LATER SUNDAY AND MONDAY BUT STILL REMAIN BELOW NORMAL. && .EXTENDED DISCUSSION (Tuesday THROUGH Friday)... Dry weather with breezy to windy conditions expected through the extended forecast period as EPAC upper ridge builds inland. Warming trend next week with high temperatures forecast near 10 degrees above normal by Friday. Periods of gusty northerly wind expected across much of interior NorCal Tuesday into Friday. && .AVIATION... VFR conditions over interior NorCal til 06z Sat then areas of MVFR/IFR becoming widespread aft 18z Sat with lcl LIFR over mtns in precip. In Central Vly, sfc wind mainly at or below 12 kts then Sly 15-30 kts with lcl gusts to 40 kts aft 07z Sat. Over higher mtns, SWly sfc wind gusts 40-50 kts possible aft 09z Sat. && .STO WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 11 AM Saturday to 8 AM PDT Sunday for West Slope Northern Sierra Nevada-Western Plumas County/Lassen Park. && $$