Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
526 FXUS66 KHNX 050414 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 914 PM PDT Thu Sep 4 2025 .UPDATE... Aviation Section Updated. && .KEY MESSAGES... 1. Chances for thunderstorms continue along the Sierra Nevada crest, though activity may be more limited similar to the activity seen yesterday. 2. An Air Quality Alert was issued yesterday by the San Joaquin Valley Air District due to the multiple fires burning across the region. This alert will remain in effect until the fires are extinguished. 3. While above normal temperatures will prevail today, the expected cooling trend will come into full swing by Friday and into the weekend with below normal temperatures for the time of year. This trend is also expected to continue through next week. && .DISCUSSION... The last remaining dregs of monsoonal moisture in the region may be enough to produce some isolated thunderstorms along the Sierra Nevada crest this afternoon, though by Friday it will be pushed out by the incoming trough from the Pacific. Those chances today are 10-20 percent, mainly located in the High Sierra north of Kern County. It is also possible given the amount of activity seen yesterday (as in just cumulus cloud build-ups and no thunderstorms) may happen again this afternoon with no cells developing. This becomes more likely tomorrow as thunderstorm chances fall below 15% and the location of those chances is pushed east. The trough that is pushing into the region will lead to a prolonged cooling trend that is expected to go through at least the next week, with the cooling beginning tomorrow. Highs are expected to first dip below normal this weekend and they are likely to lower further next week. By Wednesday, Valley highs may be in the mid 80`s with the Mojave desert in the upper 80`s. The smoke from the multiple fires across the region is causing air quality issues, so an Air Quality Alert was issued by the San Joaquin Valley Air District yesterday afternoon for the entire Valley, which will remain in effect until the fires are extinguished. The majority of the smoke continues to come out of the Garnet Fire in Fresno County. && .AVIATION... 06Z Update: VFR conditions will prevail across the central California interior for the next 24 hours. There is a 10-20 percent chance of thunderstorms over the Sierra Nevada from 19Z Fri until 06Z Sat. && .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......EW/BSO aviation....JPK weather.gov/hanford