Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
873 FXUS66 KHNX 020548 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 1048 PM PDT Mon Sep 1 2025 .UPDATE... Updated aviation section. && && .KEY MESSAGES... 1. Warm than normal temperatures as chances for triple-digits sit at around 80-100 percent today. Slight cooling trend as moisture enters the region. Better cooling by late in the week. 2. A slight chance (10-20 percent) for thunderstorms over the Sierra Nevada on Tuesday. Greater thunderstorm chances around Mid-week. 3. Marginal (at least 5 percent) risk of flooding in the very high elevations of the Sierra Nevada due to the increasing potential for thunderstorms Tuesday through Thursday. && .DISCUSSION... High pressure ridge over the region will slowly lose its grip as showers and cooler conditions invade the area. While still the dominate feature, temperatures under clear skies will rise above the triple-digit mark as widespread values range from 100 to 106 degrees across the valley. A Heat Advisory is currently in effect for the hot day ahead of cooling expected during the remainder of the week. Change is on the way as disturbances riding over the ridge will first draw in Monsoonal moisture into the district and then shift that moisture eastward. Therefore, the best chance of significant precipitation will be on Tuesday, with lingering showers and thunderstorms on Wednesday and Thursday. A strong and deeper disturbance will enter the area late in the week and introduce better drying and significant cooling. In the meanwhile, the disturbances riding over the ridge will only provide slight cooling as indicated in ensemble Probability of Exceedance (PoE) of reaching 100 degrees. Its not until Friday that PoE of reaching 100 degrees drops below 50 percent. Therefore, will continue to see warm temperatures through most of the week with near normal temperatures on Friday and going below by Sunday. Lastly, ensemble Precip-Water (PW) analysis shows the onset of 1 inch PW approaching Kern County late tonight. Probabilities worst case scenario could place between 0.75 and 1 inch of rain over the Crest of the Sierra Nevada near Mt. Whitney by Tuesday afternoon. While the flow of the storm may not allow for long-duration lingering storm over the area, The abundant moisture, with Excessive Rain Outlook guidance from Tuesday through Thursday will result in the issuance of a Areal Flood Watch to capture those isolated spots with heavy rain producing storms. && .AVIATION... 06Z Update: VFR conditions will prevail across the central California interior for the next 24 hours. After 18Z Tuesday, there is a 15 to 30 percent chance of thunderstorms over the Sierra Nevada and the Mojave Desert and Slopes. && .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... Flood Watch from Tuesday morning through Wednesday evening for CAZ327>334-337>339. Heat Advisory until midnight PDT tonight for CAZ300>317-319- 321. && $$ public...Molina aviation....JPK/McCoy weather.gov/hanford