Area Forecast Discussion
Issued by NWS Sacramento, CA
Issued by NWS Sacramento, CA
917 FXUS66 KSTO 192128 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 228 PM PDT Wed Jun 19 2024 .SYNOPSIS... Dry weather continues, with a warming trend Thursday into the weekend. Temperatures peak on Saturday, with widespread triple digit highs in the Valley and into the lower foothills. A little less hot early next week. && Key Points - Generally seasonable temperatures continue through Thursday, much warmer Friday into the weekend, hottest on Saturday. - Widespread Moderate HeatRisk is expected from Friday through Sunday -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 Saturday)... Ensembles and clusters indicate that weak upper level trough will remain over NorCal through Thursday. This trough will weaken and gradually transition into a ridge during the weekend, as an upper high strengthens over the Desert Southwest. This will have temperatures warming to slightly above normal Thursday in the 90`s, before heating up to well above normal levels from the upper 90`s to low 100`s Friday. Widespread triple digit heat is expected Saturday with Valley and lower foothill highs 100-106. Widespread Moderate HeatRisk is expected to start Friday and will continue through the weekend, with areas of Major HeatRisk on Saturday. Currently probabilities of Sacramento Valley locations (north of Sacramento metropolitan area) reaching at least 100 degrees on Friday are 50 to 90%, on Saturday 75 to 95%. From the Sacramento metropolitan area and southward into the northern San Joaquin Valley, chances are 15 to 50% probability Friday, 75 to 85% on Saturday. Outside of the Delta, winds will generally be light, helping to reduce critical fire weather conditions a bit, despite lowering relative humidity Friday and especially Saturday. && .EXTENDED DISCUSSION (Sunday THROUGH Wednesday)... Temperatures on Sunday trend a little less hot as an upper level low flattens the ridge, with HeatRisk mainly in the Moderate level. Valley highs are forecast to be in the upper 90s to low 100s. The desert Southwest high pressure ridge shifts east ward early next week as a short wave moves through, with temperatures trending a little lower. The short wave trough exits east Wednesday, allowing high temperatures to warm back up 2 to 4 degrees. && .AVIATION... VFR conditions expected over the next 24 hours across Northern California. Winds will remain below 12 kts, except for the Sacramento sites (SMF, SAC, MHR, MCC) where gusts 15-20 kts are possible between 00z-05z Thursday. && .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. && $$