Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
214 FXUS66 KSTO 220910 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 210 AM PDT Sat Jun 22 2024 .SYNOPSIS... Dry weather continues. The hottest temperatures of the week are expected today with widespread triple digits, moderate HeatRisk, and areas of Major HeatRisk. Beginning Sunday and into next week, temperatures will cool off slightly but will remain above to near normal. && Key Points - Widespread Moderate HeatRisk is expected today and Sunday, with areas of Major HeatRisk today. Areas of Moderate HeatRisk remain in the Valley Monday through Wednesday. - A Heat Advisory is in effect from 11 am to 8 pm Saturday with Widespread Moderate HeatRisk and areas of Major HeatRisk in the Valley and foothills on Saturday; Highs in the triple digits. Short-Term Discussion (Today THROUGH Tuesday)... The upper level ridge continues to build today as it moves eastward over the Desert Southwest, with daytime and overnight temperatures throughout interior NorCal increasing again. Highs in the Valley are expected to reach triple digits today, with highs in the foothills expected to be in the 90s to low 100s, and the 80s to 90s in the mountains. Moderate HeatRisk is expected over the majority of the Valley, though there are some areas of Major HeatRisk in the foothills, and portions of the central and southern Sacramento Valley and northern San Joaquin Valley. Much of the southern Sacramento Valley is spared from higher daytime and overnight temperatures, and therefore HeatRisk, by onshore flow from the Delta. Nonetheless, Moderate HeatRisk remains across much of interior NorCal through Sunday. A trough moving in from the Pacific will increase onshore flow and keep temperatures somewhat moderated on Monday and Tuesday. This leaves us with primarily Minor HeatRisk (with some areas of Moderate HeatRisk) throughout the Valley, and Valley highs generally at or below 100 degrees. The NBM has probabilities of hitting 100 degrees or more at the start of the week around 30-65% in the northern and central Sacramento Valley, and 20-55% along the eastern half of the southern Sacramento Valley and northern San Joaquin Valley. && .EXTENDED DISCUSSION (Wednesday THROUGH Saturday)... Ensembles and Clusters indicate troughing will continue through Friday, meaning onshore flow will continue to modulate temperatures in locations adjacent to the Delta. Despite this, areas of Moderate HeatRisk will cover portions of the Valley still on Wednesday, with the NBM showing a 30 to 65% probability of temperatures reaching or surpassing 100 degrees. On Thursday, as the trough continues over our area, only widespread Minor HeatRisk will remain on both Thursday and Friday. Temperatures in the Valley will remain around the low to high 90s, and in the foothills and mountains in the 80s and 70s respectively. On Saturday, clusters are in some disagreement about the movement of the trough, so NBM shows potential for temperatures falling anywhere between below normal to well above normal over the weekend. && .AVIATION... VFR conditions next 24 hours. Sustained wind will generally be below 12 kts except local southwest gusts 15-25 kts vicinity west Delta and areas of southerly gusts 15-20 kts in the Sacramento Valley 22Z thru about 03Z Sunday. && .STO WATCHES/WARNINGS/ADVISORIES... Heat Advisory from 11 AM this morning to 8 PM PDT this evening for Central Sacramento Valley-Motherlode-Mountains Southwestern Shasta County to Western Colusa County-Northern Sacramento Valley-Northern San Joaquin Valley-Southern Sacramento Valley. && $$