Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
404 FXUS66 KHNX 032326 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 426 PM PDT Wed Sep 3 2025 .UPDATE... Air Quality Alert in effect. Aviation Section Updated. && .KEY MESSAGES... 1. Chances for thunderstorms continue today, with a 10 to 25% probability for development beginning this afternoon and continuing through the rest of the daylight hours. Similar thunderstorm probabilities exist on Thursday, as well. 2. There is a Marginal Risk (at least 5%) of excessive rainfall along the Sierra Nevada crest and into the Kern Desert today and tomorrow, with a smaller area of effect on Thursday. A Flood Watch remains in effect through this evening at 11 PM. 3. While today and tomorrow are expected to see near triple digit temperatures, a cooling trend is expected to begin this Friday through at least early next week, with highs dipping below the normal temperatures expected at this time of year. && .DISCUSSION... A small disturbance off the coast of California continues to supply a small amount of moisture to the region, resulting in the further chances for thunderstorms this afternoon as well as tomorrow. Current probabilities for development are 10-25%, with the highest chances along the Sierra Nevada crest, increasing northward. These storms also have a smaller chance of producing dry lightning as the relative humidity at the surface has improved in that area since yesterday. These storms are expected to develop again tomorrow afternoon and once again on Friday, though chances decrease by about 10 percent across the region. Along with these thunderstorms, the Weather Prediction Center has issued a Marginal Risk (at least 5%) for excessive rainfall along the Sierra Nevada crest and into the Kern Desert for today and again tomorrow, though the area of effect is reduced tomorrow. Due to this, the Flood Watch issued will remain in effect through 11 PM tonight. As we look into the weekend, a pattern change is expected to take place, with troughing expected to take over from the ridge that had been in place for the last several days. This will lead to a cooling trend that is expected to begin in earnest on Friday, and temepratures are likely to cool below the seasonal average by this weekend. This trend is also expected to continue into next week, with the Valley cooling into the upper 80`s and the Mojave Desert into the mid 90`s. The Climate Prediction Center also has the region in a leaning below normal (33-40%) through Day 14, which would be mid-way through this month. && .AVIATION... 0Z Update: VFR conditions will prevail across the central California interior for the next 24 hours. There is a 10-25 percent chance of thunderstorms over the Sierra Nevada and the Mojave Desert and Slopes through 06Z Thu. There is a 5 to 15 percent chance of thunderstorms over the Sierra Nevada after 18Z Thu. && .AIR QUALITY ISSUES... See the latest air quality alert /AQAHNX/ for details. && .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...BSO aviation....JPK weather.gov/hanford