Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
330 FXUS66 KSTO 152008 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 108 PM PDT Thu Aug 15 2024 .SYNOPSIS... Near normal to slightly below normal temperatures over the next week. Saturday will be breezy with a slight chance of showers north of Redding in higher terrain. && .Discussion... Friday...good agreement in ensemble systems that anomalously strong upper trough begins to deepen off the coast of Oregon. This will cool temperatures a bit and keep a onshore flow into the forecast area. Saturday...the upper trough deepens even more with the center of the system staying nearly stationary. Thicknesses fall for even cooler conditions. Surface pressure gradients will increase across the area which will result in an uptick in southerly winds. Would normally be a higher risk fire day but relative humidities really take an uptick as temperatures fall. Will be isolated areas of higher fire danger but overall the higher humidities keep us well below local red flag warning criteria. In the far north in northwest Shasta county...some energy from the mentioned upper trough looks to kick off a few showers and maybe (10 to 25% chance according to NBM) of an isolated thunderstorm. Have kept that chance going from previous forecasts and expanded the chance of thunder slightly. Sunday...really very little change in the upper pattern as the trough remain parked off the coast of Oregon with southwest onshore flow over the forecast area for temperatures at or below normal for this time of the year. && .EXTENDED DISCUSSION (Monday THROUGH Thursday)... Good agreement in ensemble data that the pre-mentioned upper trough will remain off the coast but slowly fill through the extended period. The steering winds with the trough and the southwest U.S. ridge will take any subtropical moisture off to our south and west. Temperatures should slowly warm through the period warming to normal to slightly normal from normal to slightly cooler than normal. Rasch && .AVIATION... VFR conditions prevail next 24 hours across interior NorCal except isolated MVFR possible in HZ/FU after 00z in northern Sacramento Valley. South to west surface winds less than 12 kts expected, although some gusts to 20 kts possible in the Delta vicinity and northern San Joaquin Valley through 06z. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$