Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
684 FXUS66 KSTO 240755 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 1255 AM PDT Tue Sep 24 2024 .Synopsis... Hot weather continues with Moderate HeatRisk today, then cooler temperatures return Wednesday and Thursday. Temperatures warm up again on Friday and Saturday with Moderate HeatRisk before returning to near/slightly above normal high temperatures into next week. && .Discussion... Mostly clear and light, variable winds prevail around interior NorCal early this morning. The hot weather will stay around with us for one more day, as broad ridging aloft will continue to dominate the synoptic pattern today. The National Blend of Models (NBM) advertises around a 20-60% chance of high temperatures reaching 100 degrees in the Valley/Delta and the thermal belts of the foothills today. The best chances will be in the Sacramento area, the Delta, and the northern Sacramento Valley. Although the NBM is not favoring widespread triple-digits, given the upper- level pattern and generally light winds forecast for today, we could see several locations in the Valley hit the triple digit mark this afternoon. On Wednesday, upper level troughing from the Pacific Northwest will help lower heights over the area, as well as enhance onshore flow so high temperatures will fall into the low 80s and low 90s for the Valley/foothills, with upper 70s forecast for the higher elevations. Breezy to locally gusty winds are also in the forecast for Wednesday. The Valley could see wind gusts around 15-25 mph Wednesday afternoon and the Delta could see wind gusts up to 30 mph, as the trough moves through NorCal. Little to no precipitation is anticipated at this time however, as the trough is lacking significant/efficient moisture to cause any significant precipitation concerns for the area. Humidity values will also increase Wednesday thanks to the enhanced onshore flow and the trough moving through, with daytime humidity values in the upper 20s to mid 30s with better overnight recoveries expected as well. Thursday, our pattern will begin to shift again, as a more zonal upper level flow overtakes the area, with a weak closed low off the Baja California coast and ridging developing the Four Corners Region. These somewhat stagnant heights will lead to another slight warming trend heading into the end of the work week, where temperatures will climb into the mid to upper 90s for the Valley. Upper level troughing will begin to move eastward in the PacNW, and with the weak closed low off the Baja California coast we will see northerly winds and poor daytime/overnight humidity values, which could setup another period of elevated fire weather concerns on Friday. && .EXTENDED DISCUSSION (Saturday THROUGH Tuesday)... As we head into the weekend, ensembles and clusters show a weak area of high pressure develop over NorCal, which will raise our heights slightly and keep temperatures slightly warmer than normal for this time of year. High temperatures will continue to be around 5-10 degrees above normal through the extended forecast period. There remains some variability with the temperature forecast and the upper level pattern that will develop, as the NBM shows a 5-10 degree temperature difference from the mean temperature forecast, so expect the high temperature forecast to fluctuate as we move through the work week. Even with the slightly higher than normal temperatures forecast, HeatRisk looks to remain Minor throughout the extended forecast with only isolated areas of Moderate HeatRisk on Monday mainly in the foothills/thermal belts. Wood && .AVIATION... VFR conditions persist across interior NorCal next 24 hours. Surface winds generally less than 12 kts expected, with breezy north to east winds through the morning shifting to south to west winds after 18z. Some gusts to 25 kts then possible across the Delta vicinity through the evening. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$