Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
242 FXUS66 KHNX 021902 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 1202 PM PDT Tue Sep 2 2025 && .KEY MESSAGES... 1. Increased chance for thunderstorms exist today and tomorrow along the Sierra Nevada mountains and into the Kern County mountains, with a 15 to 30 percent probability of development this afternoon and a 15 to 25 percent chance on Wednesday. These storms are likely to produce little rainfall and result in dry lightning strikes. 2. There is at least a 5% chance for excessive rainfall in the Sierra Nevada mountains into the Kern County mountains and desert today and tomorrow, which resulted in the issuance of a Flood Watch of those regions. 3. Moderate Heat Risk continues for the Valley and Mojave Desert through this afternoon, with a 40 to 80 percent chance for triple digits in the Valley. && .DISCUSSION... A low pressure system off the coast of Central California in bringing in a small amount of moisture and enough lift to lead to the development of thunderstorms this morning, which were fast moving cells that quickly exited our CWA. Continued thunderstorm development is likely this afternoon with a 15 to 30 percent chance for development along the Sierra Nevada mountains, and a 10 to 15 percent chance for thunderstorms in the Kern County mountains and Mojave Desert. Thunderstorm chances slightly decrease tomorrow, though chances of 15 to 25 percent remain in the Sierra Nevada that afternoon. Thunderstorm chances fall off by the end of the workweek with chances of only 5 to 15 percent. The Weather Prediction Center has put a Marginal Risk (at least 5%) for excessive rainfall along the Sierra Nevada and into the Mojave Desert and Kern Mountains today and tomorrow, and to a lesser extent on Thursday. Due to this risk today, a Flood Watch has been issued for the Kern County Mountains and Desert, and into the Southern Sierra Nevada. This will be in effect until Wednesday evening. Triple digits are likely again this afternoon, with a 40 to 80 percent chance of those temperatures in the San Joaquin Valley. This results in a mostly Moderate Heat Risk with some areas of Major Heat Risk in the higher elevations of the Valley approaching the foothills on either side of the Valley. These temperatures are expected to cool through the week, with Heat Risk becoming mostly Minor on Friday. && .AVIATION... 18Z Update: VFR conditions will prevail across the central California interior for the next 24 hours. There is a 15 to 30 percent chance of thunderstorms over the Sierra Nevada and the Mojave Desert and Slopes through 06Z Wed. && .AIR QUALITY ISSUES... None. && .CERTAINTY... The level of certainty for days 1 and 2 is medium. 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... Flood Watch through Wednesday evening for CAZ327>334-337>339. && $$ Public/Aviation/Fire Weather...EW DSS/PIO........................JPK weather.gov/hanford