Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
172 FXUS66 KSTO 062025 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 125 PM PDT Thu Jun 6 2024 .SYNOPSIS... Hot, well above normal temperatures persist through the remainder of today, with a gradual cooling trend into the weekend and then another warm up into early next week. Additionally, late day isolated mountain thunderstorms will remain possible as well. && .DISCUSSION... Key Points - An Excessive Heat Warning remains in effect through 8 PM PDT this evening across the Valley and adjacent foothills. - Areas of Major HeatRisk continue today, with Moderate HeatRisk by Friday; Triple digits in the Northern and Central Sacramento Valley and adjacent Valley foothills, less hot in the Delta and Sacramento metro area with highs in the mid to upper 90s. - Less hot this weekend, through with some areas of Moderate HeatRisk, mainly over the northern and central Sacramento Valley. - Another warm up is expected, with well above normal temperatures returning, for Monday and Tuesday. Moderate HeatRisk returns to much of the Valley and foothills on these days, with areas of Major HeatRisk in the northern and central Sacramento Valley. Short-Term Discussion (Today THROUGH Sunday)... As of early this afternoon, mostly quiet weather is ongoing for much of interior NorCal, although some cumulus development is being noted over the Coastal Range in Tehama and Shasta counties. This may result in some isolated thunderstorm development in the northern Sacramento Valley through the afternoon and evening. Any thunderstorms that do develop will be capable of brief heavy rain, gusty winds, and small hail, as well as potential new fire starts from lightning. Otherwise, hot and dry weather is expected to persist elsewhere. Valley high temperatures look to top out in the mid 90s to triple digits, with 80s to low 90s still at higher elevations. Looking aloft, the ridge axis has become centered further eastward over the Intermountain West, with troughing over the eastern Pacific inducing west-southwesterly flow across interior NorCal. This is resulting in the return of south to west onshore surface flow to the region, which will usher in the anticipated gradual cool down that is expected from Friday into the weekend. High temperatures cool to simply above normal with moderate HeatRisk in the Valley and foothills for Friday, and further to near to slightly above normal temperatures and primarily minor HeatRisk for the weekend. As the flow pattern shifts to onshore flow, winds look to become diurnally breezy to gusty, with gusts of 20 to 25 mph in the afternoon and evening hours, primarily across the Delta and into portions of the Sacramento and northern San Joaquin Valley. Additionally, a weak trough is expected to travel through the flow pattern Saturday into Sunday, which may provide enough lift for some isolated mountain thunderstorm chances along the Sierra crest (currently 10-20% probabilities). To view the latest HeatRisk, please visit www.wpc.ncep.noaa.gov/heatrisk/ To view current water temperatures, please visit www.cnrfc.noaa.gov && .EXTENDED DISCUSSION (Monday THROUGH Thursday)... Ensemble clusters continue to be in good agreement that a quieter weather week is in store as ridging moves through the Pacific NW/Northern CA with troughing over SoCal. By midweek, a closed low are projected to be over SoCal with troughing moving through the Pacific NW. This will allow for several days of the Delta Breeze helping to marginally cool portions of the Valley from seeing the peaks in temperatures we are experiencing this week. All this being said, we are still projecting Moderate Heat Risk in the Sacramento Valley with areas of Major Heat Risk across the northern Sacramento Valley and northeastern foothills. Tuesday is forecasted to be the warmest day with highs near or above triple digits across much of the Valley. NBM probabilities indicate a 40-85% chance of exceeding 100 degrees on Tuesday, with highest chances along the foothills and Northern Sacramento Valley. This time of the year please continue to practice heat safety as hot temperatures will be apart of our forecast into midweek next week! && .AVIATION... VFR conditions prevail over interior NorCal through the forecast period. Light to breezy south-southwest winds through the Sacramento Valley thru 04z Fri with lingering gusts up to 10-20 MPH across the Delta and western portions of the Southern Sacramento Valley through 18z Fri. && .STO WATCHES/WARNINGS/ADVISORIES... Excessive Heat Warning until 8 PM PDT this evening for Carquinez Strait and Delta-Central Sacramento Valley-Motherlode-Mountains Southwestern Shasta County to Western Colusa County-Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-Northern San Joaquin Valley-Shasta Lake Area / Northern Shasta County- Southern Sacramento Valley. && $$