211 FXUS66 KHNX 171940 AFDHNXArea Forecast Discussion National Weather Service Hanford CA 1240 PM PDT Wed Sep 17 2025
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.KEY MESSAGES... 1. 5 to 10 percent chance of thunderstorms in southwestern Kern County today. 10 to 30 percent chance widespread across the San Joaquin Valley, Sierra Nevada and Mojave Desert Thursday into Friday morning. For late Friday morning until late Friday night, 10 to 25 percent chance of thunderstorms over the Sierra Nevada and Mojave with a 5 to 15 percent chance in the San Joaquin Valley.
2. Flood Watches in effect from early Thursday morning through late Friday night due to the thunderstorms and heavy rain from the remnants of Mario.
3. Minor chances (less than 30 percent) to exceed 100 degrees Wednesday for localized areas of the San Joaquin Valley and Mojave Desert. Temperatures will cool Thursday into the weekend.
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.DISCUSSION... Some morning thunderstorms greeted southwestern Kern County this morning, however, another warm day is in store today. However, the ridge of high pressure which brought warmer temperatures yesterday and today will weaken and move east allowing the remnants of post-tropical cyclone Mario to pump moisture in our area bringing thunderstorm chances and cooler temperatures to the area. Flood Watches are in effect from Thursday morning through late Friday night due to the potential of thunderstorms especially over burn scars could produce flooding. There is a widespread 15 to 30 percent chance of thunderstorms on Thursday for most of the Valley, Sierra Nevada, and Mojave Desert.
This storm brings a 35 to 70 percent chance of at least quarter of an inch of rain or more to the San Joaquin Valley. Friday has a 10 to 30 percent chance of thunderstorms for the Sierra Nevada and the Mojave while the Valley has a 5 to 15 percent chance of thunderstorms. Saturday and Sunday have 5 to 15 percent probabilities of thunderstorms as the low moves west. A ridge will develop over the weekend bringing temperatures back up and drier conditions. However, ensembles have some disagreement about next week regarding the strength of another trough. However, probabilities already show a 15 to 30 percent chance of at least quarter inch of rain to the Valley next Tuesday which will be something to monitor after Friday.
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.AVIATION... 18Z Update:
VFR conditions will prevail across the Central California Interior for the next 24 hours. Areas of Dense Smoke aloft along the Sierra Nevada over eastern Fresno County and nearby counties from the Garnet Fire may impact visibility. However, thunderstorm chances increase after 12Z Friday to 5 to 15 percent in Kern County.
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.AIR QUALITY ISSUES... None.
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.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.
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.HNX WATCHES/WARNINGS/ADVISORIES... Flood Watch from late tonight through Friday afternoon for CAZ321-322-331>339. Flood Watch from Thursday afternoon through Friday afternoon for CAZ304>316. Flood Watch from Thursday morning through Friday evening for CAZ317>320-323>330. &&
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JPK
weather.gov/hanford
NWS HNX Office Area Forecast Discussion