Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
693 FXUS66 KHNX 060613 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 1113 PM PDT Fri Sep 5 2025 .UPDATE... Updated aviation section. && && .KEY MESSAGES... 1. There is a slight chance (5-15%) for thunderstorms this afternoon along the Sierra Nevada crest, with chances falling below 5% tomorrow afternoon and remaining at that level through the weekend. 2. The cooling trend is expected to continue today with highs across the region approaching normal values for this time of year. Temperatures will begin to dip below normal over the weekend and further still into early next week. && .DISCUSSION... The last, small amount of monsoonal moisture that is lingering along the Sierra Nevada crest has a 5 to 15% chance for producing thunderstorms this afternoon, though this has the stronger likelihood of mainly producing cumulus and a few towering cumulus clouds, similar to the past couple days. After today, the thunderstorm chances fall further down to less than 5%, where even cumulus clouds may struggle to form over the Sierras. Causing that decrease in thunderstorm potential is an incoming trough from the Pacific, which is expected to be stronger than what is normally seen at this time of year. If those conditions materialize, this trough will lead to a fairly significant cooldown for the region, with temperatures in the Valley 5 to 10 degrees below normal by mid next week. Highs today are expected to be around normal for this time of year, and becoming slightly below normal by the weekend. Long term models are also signaling that this cooldown will be somewhat short lived as zonal flow may begin to take over by next weekend in the middle of the month, which would lead to the return of near normal to above normal temperatures. && .AVIATION... 06Z Update: VFR conditions will prevail across the central California interior for the next 24 hours. && .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... None. && $$ public/fire weather...EW aviation....McCoy weather.gov/hanford