Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
759 FXUS66 KSTO 162048 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 148 PM PDT Mon Sep 16 2024 .Synopsis... Cooler unsettled weather thru mid-week with periods of showers and isolated thunderstorms. Dry and warmer weather returns late in the week into next weekend. && .Discussion... Our weather system continues its trek through Central CA into Nevada with radar showing scattered showers along and east of the Sierra with light snow showers over the higher peaks of the Sierra south of HWY. 50. Showers and isolated thunderstorm will wrap around and send showers into our area from the northern Sierra moving southwestward but remaining mainly over the mountainous areas north of I-80. NBM shows a 10-20% chance of thunderstorm development with highest chances across the Southern Cascades and adjacent foothills. With each pass of showers this evening, active weather should trend eastward and eventually tapering off and exiting our area by late tonight into early morning Tuesday. 0.01" to 0.30" is forecasted over the Sierra and Southern Cascades with a 5-25% chance of seeing amounts over a quarter of inch. Once things taper off Tuesday morning, we will see a brief break in active weather ahead of another weather system moving in late Tuesday through Wednesday. The weather system is tracking further south than Sunday`s active weather, making the Sierra and adjacent foothills the favored location for showers and thunderstorms. The Sierra and adjacent foothills are slated to see around 0.25-0.60" of rain, highest from I-80 southward. Elsewhere, amounts are under a tenth, highlighting the chances for pop-up showers over the Central Valley but not any organized and long duration rainfall. NBM shows a 70-90% chance of rain amounts greater than 0.25" over the Sierra with 50-70% across the adjacent foothills. Heaviest rainfall is expected Wednesday morning, along the crest of the Sierra. Snow levels remain above pass level so is not expected to accumulate on the roadways. With the rounds of active weather, this pattern is keeping below normal temperatures through midweek before things warm later this week heading into the weekend. The beginning of this week including today will see Valley highs in the 70s to upper 80s but return back to normal temperatures (upper 80s, low 90s) by this weekend. Conditions remain relatively moist this week but with the late week warmup, areas of the Northern Sacramento Valley will see afternoon humidities drying back to around 20-30% Min. RHs. .EXTENDED DISCUSSION (Friday THROUGH Monday)... Dry weather expected through the extended forecast period as high pressure extends inland over NorCal. High temperatures expected to return to near normal Saturday into early next week. Each day will see conditions dry in the Valley into next week and by Monday see afternoon humidities around 20-30% && .AVIATION... In Northern Sac. Valley, isolated MVFR conditions possible at times from shra til 03z Tue, otherwise mainly VFR next 24 hrs. Surface wind generally below 12 kts except for Delta after 05Z which the surface gust winds are upward to 20kts. Over foothills and mountains, areas of MVFR/IFR possible from isolated showers and thunderstorms creating mountain obscuration thru 06z Tue. Snow levels above 7k ft. Local westerly surface wind gusts to 20 kts possible over higher terrain through 00z Tuesday. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$