Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
840 FXUS66 KSTO 210800 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 100 AM PDT Fri Jun 21 2024 .SYNOPSIS... Dry weather continues, with a warming trend into the weekend. Temperatures peak on Saturday, with widespread triple digit highs in the Central Valley and into the lower foothills. A little less hot early next week. && Key Points: - Widespread Moderate HeatRisk is expected today through Monday, with areas of Major HeatRisk today-Saturday - A Heat Advisory is in effect from 11 am to 8 pm Saturday with Widespread Moderate HeatRisk and areas of Major HeatRisk in the Central Valley and foothills on Saturday; Highs in the triple digits. Short-Term Discussion (Today THROUGH Monday)... Ensembles and clusters indicate that the transition to upper level ridge will begin over NorCal today. The ridge will amplify over the weekend, as an upper high strengthens over the Desert Southwest. This will cause temperatures to heat up to well above normal levels from the upper 90`s to low 100`s today. Widespread triple digit heat is expected Saturday with Central Valley and lower foothill highs 100-106. Some Delta air will modify the late afternoon high temperatures over the Delta, and portions of the southern Sacramento Valley keeping most of these areas in moderate heat risk versus major to the north and over the foothills. Increasing southwest flow is expected over NorCal Sunday, as a trough moves through the Pacific Northwest. This will likely initiate an afternoon Delta breeze with high temps a few degrees cooler in the upper 90`s and low 100`s. Widespread Moderate HeatRisk expected through Monday, with areas of Major HeatRisk today and Saturday mainly over the Sierra foothills & northern Sacramento Valley. The National Blend of Models (NBM) is indicating a 80-100% chance of temperatures greater than 100 degrees F throughout most of the Valley on Saturday. By Sunday, a trough is expected to move through the Pacific Northwest resulting in increased southwesterly flow. This will translate into a more robust Delta breeze on Sunday with gusts 15-25 mph through the Valley. Slightly cooler temperatures will follow, but Moderate HeatRisk is expected to continue across most of the Central Valley and foothills through Monday. && .EXTENDED DISCUSSION (Tuesday THROUGH Friday)... Interior NorCal sandwiched between Desert SW high and short wave trough to the NW Tuesday into Wednesday. High temperatures in the Central Valley expected from the upper 90s to around 102, hottest in the Northern Sacramento Valley. Cooling around 2 to 5 degrees Thursday into Friday as short wave trough pushes into the PacNW and heights lower over the CWA. && .AVIATION... VFR conditions over interior NorCal next 24 hrs exc lcl MVFR/IFR possible in ST vcnty of Delta til 17z. Sfc wind mainly below 12 kts except vcnty of Delta SWly sfc wind 15-25 kts. && .STO WATCHES/WARNINGS/ADVISORIES... Heat Advisory from 11 AM to 8 PM PDT Saturday for Central Sacramento Valley-Motherlode-Mountains Southwestern Shasta County to Western Colusa County-Northern Sacramento Valley- Northern San Joaquin Valley-Southern Sacramento Valley. && $$