Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
423 FXUS66 KSTO 272200 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 300 PM PDT Thu Jun 27 2024 .SYNOPSIS... Seasonable, dry, and periodically breezy weather persists through the remainder of the week and into the weekend. Confidence is high in hot weather with widespread Major HeatRisk next week. breezy north winds and low humidity will bring fire weather concerns early next week, especially the northern Sacramento Valley. && Key Points - Likely a major heat event next week, impacting holiday outdoor events. - Elevated fire weather conditions Monday and Tuesday. .Discussion...Ensembles continue to show a weak trough is forecast to linger across the region through the weekend. A shallow Delta breeze will bring some cooling into influenced areas for nights and mornings, as well as some local gusts to 20 mph. High temperatures increase 2 to 5 on Friday compared to today, with highs approaching 100 for the northern Sacramento Valley. Little change is expected over the weekend, with areas of Minor to Moderate HeatRisk. && .EXTENDED DISCUSSION (Monday THROUGH Thursday)... By Monday, the eastern Pacific ridging extends eastward into California, beginning a strong warming trend. The National Blend of Models (NBM) has probabilities of Valley temperatures reaching 100 degrees or more at 55 to 85% on Monday, 75 to 95% on Tuesday, and 80 to 100% on Wednesday. Widespread Moderate HeatRisk with areas of High HeatRisk develops on Monday, becoming widespread Major HeatRisk by Tuesday. Confidence is increasing in significant heat event from Monday through the 4th of July holiday as the eastern Pacific ridge continues to build and move eastward inland. Widespread triple digit heat is expected, increasing further on Tuesday and peaking on WednesLTDAFDSTOday. Hottest temperatures are currently projected by the NBM to be around 110 degrees for the northern Sacramento Valley Wednesday afternoon/evening. There is enough confidence in this heat event to issue an Excessive Heat Watch from late Monday morning through Thursday (Independence Day) evening. Heat could significantly impact outdoor holiday activities, so plan ahead. The main uncertainty at this point is how long this event will continue. Currently, some weakening of the ridge with light onshore flow is expected Thursday night, bringing less hot temperatures for Friday. Monday and Tuesday will likely see breezy north and northwesterly winds, with strongest gusts in the northern and central Sacramento Valley in the afternoon and evening. This combined with the very conditions will bring enhanced fire weather concerns. Current timing of these local conditions are in the mid to late afternoon of each day. && .AVIATION...LTDAFDSTO VFR conditions over interior NorCal next 24 hours. Surface wind mainly below 12 knots except vicinity of Delta southwesterly surface wind gusts up to 20 kts at times. && .STO WATCHES/WARNINGS/ADVISORIES... Excessive Heat Watch from Monday morning through Thursday evening for Central Sacramento Valley-Motherlode-Mountains Southwestern Shasta County to Western Colusa County-Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-Northern San Joaquin Valley-Southern Sacramento Valley. && $$