645 FXUS66 KHNX 041910 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 1210 PM PDT Wed Jun 4 2025 && .KEY MESSAGES... 1. Minor Heat Risk is expected in the San Joaquin Valley through Thursday before Moderate Heat Risk returns on Friday into early next week. 2. There is a 15 to 30 percent chance for thunderstorms in the Sierra Nevada mountains this afternoon, with the Storm Prediction Center issuing a General Risk for thunderstorms in the mountains for both of those days. && .DISCUSSION... Today presents another chance for thunderstorms in the Sierra Nevada, with current probabilities of 15 to 30% for these to develop, mainly in the afternoon. Any cell that forms may have localized heavy rainfall and frequent lightning. The moisture that fuels these storms is being brought in by a disturbance off the Southern California coast. Once that feature weakens and moves east, the moisture won`t be able to flow into the Sierra Nevada and thunderstorm chances will decrease, though chances tomorrow are still 10 to 20%. These chances remain steady for the Sierra Nevada through Friday. As those thunderstorms form in the Sierra Nevada, the San Joaquin Valley will continue to see a Minor Heat Risk during the day, with highs in the mid 90`s. As we move into the weekend, temperatures will gradually increase and by Friday, Moderate Heat Risk is expected to return to the Valley as highs rise into the triple digit range by Monday. The Moderate Heat Risk is expected to continue through at least next Wednesday, though current models show the heat backing off below 100 degrees in the Valley by Wednesday. Relative humidity during this week is expected to be fairly steady at around 20 to 25%, with a gradual lowering by Tuesday as temperatures rise, though winds should remain light and thereby keeping the fire risk from increasing. && .AVIATION... 06Z Update: VFR conditions will prevail for the next 24 hours across the Central California Interior. A 15-30 percent chance of thunderstorms exists in the Sierra Nevada from 18Z Wed through 03Z Thu. && .AIR QUALITY ISSUES... ISSUED: 06/03/2025 15:24 EXPIRES: 06/04/2025 23:59 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... None. && $$ Public/Aviation/Fire Weather....EW DSS/PIO.........................SM weather.gov/hanford