Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
601 FXUS66 KHNX 271802 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 1102 AM PDT Wed Aug 27 2025 && .KEY MESSAGES... 1. 5 to 30 percent chance of thunderstorms over the Sierra Nevada and foothills. 2. Marginal (5 to 15 percent) risk of excessive rainfall from Yosemite to northeastern Tulare County over the Sierra Nevada. 3. Temperatures continue to cool through Friday before a warmup over Labor Day weekend. && .DISCUSSION... Thunderstorm potential has gone down today as the ridge of high pressure over the Four Corners begins to slowly move west and shift its axis tilt. This change slowly but surely will cut off the moisture especially the remnants from Juliette in the Pacific. There is a 5 to 30 percent chance of thunderstorms today over the Sierra Nevada and foothills which brings a marginal risk of excessive rainfall. However, the decrease in moisture in any of these thunderstorms increases the potential of more fires starting from strikes. The potential for thunderstorms will continue to drop to be at 10 percent or below over the holiday weekend. Upper level winds will continue to become more on-shore from the west as the ridge moves helping with the cooler temperatures.Temperatures will increase over the weekend as the ridge continues to build as it moves west over California. Sunday has a 30 to 70 percent chance of triple digits in the Valley before it decreases on Labor Day to 20 to 60 percent. After the holiday, probabilities drop back down to 25 percent or less on Tuesday and Wednesday. Minimum RH values will be in the 20 to 30 percent range for the next few days which would play a factor in some of the ongoing fires. && .AVIATION... 18Z Update: A 5 to 30 percent chance of thunderstorms over the Sierra Nevada and adjacent foothills for the next 24 hours until 03Z Thursday. Otherwise, VFR conditions are expected in the San Joaquin Valley for the next 24 hours. && .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... None. && $$ public...JPK aviation....EW weather.gov/hanford