The Latest NWS Regional Area Forecast Discussions
Select Your Area NWS Weather Forecast Office
NWS Area Weather Forecast Discussion
County Warning Area [CWA]: STO Regional NWS Weather Office: Sacramento, CA 962 FXUS66 KSTO 060834 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 134 AM PDT Sun Oct 6 2024 .Synopsis... Well above normal temperatures continue into early this week, with widespread Moderate to Major HeatRisk in the Valley, Delta, and Foothills. Slight (5-15%) chance of high elevation mountain showers Sunday and Monday afternoon along the Sierra Crest; gradual cool down begins Tuesday with possible shower chances north of I-80 and higher elevations late this week. .Discussion... Another unseasonably hot October day is in store for interior NorCal with widespread Moderate to Major HeatRisk to accompany triple digit afternoon highs. Upper level ridging located in the Four Corners Region continues to dominate the synoptic pattern, which is also weakening the cooling impacts of the Delta Breeze, leading to warm overnight lows in the mid to upper 60s and low 70s. The Heat Advisory will continue until 11 PM tonight, with some considerations of possibly extending the Advisory until Monday, as temperatures have trended up from previous forecast model runs. As mentioned above, temperatures are forecast to remain in the upper 90s to around 102 on Monday, with the hottest temperatures once again in the Delta, southern Sacramento and Northern San Joaquin Valleys, and the Foothill thermal belts. A weak embedded trough riding along the ridge will introduce slight shower chances (5-15%) along the Sierra Crest Sunday evening and Monday evening, but no significant precipitation or thunderstorms are anticipated at this time. We will finally start to see some relief from the oppressive heat that has made early Fall feel more like Summer, as the ridge will begin to breakdown and PacNW troughing will begin to influence our synoptic pattern. With troughing returning, we will see high temperatures slowly start to fall, although they will still be warmer than what is climatologically normal for this time of year by 5-12 degrees. Overnight lows will also see a return to the mid 50s to low 60s Tuesday. Wednesday, troughing will continue to remain in the PacNW, and heights over NorCal will somewhat flatten, which will induce westerly flow and more cooling across the area. High temperatures will be in the upper 80s to low 90s, with the 90s forecast in the northern Sacramento Valley. Attendant HeatRisk will be Minor across the region, finally breaking the stretch of Moderate to Major HeatRisk. && .EXTENDED DISCUSSION (Thursday THROUGH Sunday)... Cooling trend Thursday into Friday as heights/thicknesses trend down in response to short wave trough in the EPAC approaching the West Coast. Models continue to handle this wave differently with GFS showing a more dynamic system but keeps the track farther north into the PacNW than EC. At this time it appears some light precip possible over Shasta county Friday into early Saturday. Main impact looks to be additional cooling Friday with increased onshore flow. Below normal high temperatures expected Friday. Upstream upper ridging then modeled to build into NorCal over the weekend resulting in warming temperatures with highs near to slightly above normal. && .AVIATION... VFR conditions over interior NorCal next 24 hrs with sfc wind generally below 12 kts except lcl NW-NE sfc wind to 15 kts with gusts to 20 kts in the foothills/mtns til 18z Sun. && .STO WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 11 PM PDT this evening for Carquinez Strait and Delta-Motherlode-Northern San Joaquin Valley-Southern Sacramento Valley. && $$
|