Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
209 FXUS66 KHNX 211731 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 1031 AM PDT Fri Aug 21 2026 .KEY MESSAGES... 1. Warmup continues today before trending back to seasonal averages. 2. Monsoonal moisture brings 5 to 15 percent chance of thunderstorms over the Sierra Nevada Friday into Saturday. 3. Breezy conditions take place over typical wind-prone areas including San Luis Reservoir, Lake Isabella and the Mojave Desert Slopes. && .DISCUSSION... High pressure ridge over the West expected to shift east in the next 24 hours as a disturbance rides over the top. Short range ensemble upper-air analysis as the disturbance moving ashore tonight and pushing deep into the Pacific Northwest on Saturday. In the meanwhile, the ridge remains over the West Coast as triple digit heat will be observed this Friday. Currently, Probability of Exceedance (PoE) of reaching 100 degrees sit at 60 to 80 percent from Fresno To Bakersfield, respectively. Areas north of Fresno have PoE dropping to less than 10 percent. Therefore, while patches of Moderate Heat Risk will be present over the South Valley and Mojave Desert, elsewhere, Minor Heat Risk will be present. The passage of the Disturbance will allow for some wind increase a lowering of the Heat Risk on Saturday. Afterward, the disturbance will exit the region with a rebound of the ridge ahead of another disturbance traveling through the Pacific Northwest which will prevent any big warm-up for the next five to seven days. The next hot day will be on Monday as PoE of reaching 103 degrees will range from 30 to 60 percent for areas south of Fresno County. The passage of the disturbance will also introduce an increase in the southwesterly to westerly wind component during the coming days. Currently, the flow is more southerly and is allowing for a northward surge of Monsoonal Moisture into the region. With the southwest winds aloft on Saturday, enough orographic lift will exist to support thunderstorm development across the Sierra Crest. Latest ensemble probability of thunder has between a 10 to 20 percent chance of development Saturday Afternoon along the Sierra Nevada Crest from Yosemite to the Tulare/Kern County Line. By Sunday, the flow aloft becomes more westerly and forces the moisture to shift east and more into the Great Basin. Therefore, while convection is possible on Saturday, Central California will lose the ingredients for thunderstorm development by Sunday as the probability of thunder drops to below 10 percent from that day and forward through the week. && .AVIATION... VFR conditions will prevail for the next 24 hours. && .AIR QUALITY ISSUES... None. && .CERTAINTY... The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit www.weather.gov/hnx/certainty.html for additional information and/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... None. && $$ Public/Aviation....Molina weather.gov/hanford