Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
428 FXUS66 KSTO 242035 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 135 PM PDT Fri May 24 2024 .SYNOPSIS... A brief cool down with onshore flow through Saturday, and isolated shower chances this afternoon and evening over the mountains. Warmer and drier weather then returns Sunday into next week, with periodically breezy winds. && .DISCUSSION... Current GOES-West visible satellite imagery shows mostly sunny skies across much of interior northern California on this Friday afternoon, with the exception of a few high cirrus clouds passing by overhead, and decent culumus cloud development over the northern Sierra Nevada and southern Cascades. Temperatures are currently trending approximately 3 to 12 degrees cooler than this time yesterday afternoon, mainly in the Valley and foothills, valid at 130 PM PDT. Locally breezy onshore winds are being observed as broad troughing with an embedded shortwave influences the region. Forecast highs today and Saturday will be trending cooler than the climatological normal for late May as a result of these features, along with periods of breezy onshore winds. In addition, there is a slight chance for isolated showers or even a brief thunderstorm this afternoon/evening in the mountains, mainly over the Sierra Crest. Upper level ridging starts to build in Sunday into next week, bringing some rising heights and a resultant warming trend to the region. High temperatures are expected to reach closer to normal on Sunday, with highs in the 80 to 88 degree range in the Valley. Slightly above normal temperatures are then forecast for the Memorial Day Holiday, with highs generally in the 82 to 92 degree range for the Valley. Ensemble guidance then shows the upper level ridge slowly shifting eastward toward the Great Basin early to mid next week. && .EXTENDED DISCUSSION (Tuesday THROUGH Friday)... Ensemble guidance and cluster analysis indicate the upper level ridging to be primarily over the Great Basin in the middle of next week, with troughing developing to the north and west. This will allow for locally breezy onshore flow at times over the extended forecast period. Slightly above normal temperatures look to continue through much of next week, with mainly Minor Heat Risk. Towards the end of the week there is a bit more uncertainty on the potential outcomes of the trough and ridge influence in the cluster analysis, which is resulting in a decent spread of high temperatures for late next week. && .AVIATION... Mainly VFR conditions next 24 hours, except possible MVFR/IFR in marine stratus from about 11Z-17Z Saturday (50-90% probability in the Delta and in the Valley south of Chico and north of Stockton). Local southwest surface wind gusts 20-30 kts in the Delta and over the Sierra, areas of southerly wind gusts 15-25 kts in the Sacramento Valley, and west-northwesterly 15-25 kts across the northern San Joaquin Valley. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$