Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
894 FXUS66 KHNX 052339 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 440 PM PDT Tue Aug 5 2025 .KEY MESSAGES... 1. A warming trend begins Today with triple digits returning on Thursday. 2. There is a 15 to 20 percent chance of high temperatures of at least 103 degrees on Thursday before increasing to 30 to 50 percent chance during the weekend. 3. Minor fire risk with widespread minimum relative humidity between 15 and 25 percent for the non-desert areas. Minimum relative humidity expected to be less than 10 percent in the Mojave Desert with breezy winds in the afternoon to evening. && .DISCUSSION... Four Corners High Pressure Ridge now taking hold of the west as we enter our next warm-up. While the westerlies are still far enough south to keep Central California at about seasonal normal, temperature-wise, short range ensembles show the westerlies shifting north. Therefore, as the four-corners high becomes the dominate feature over the West, will see a warming trend through remainder of the week as widespread triple digits take hold of the San Joaquin Valley by the end of the week. Ensemble Probability of Exceedance (PoE) of reaching 100 degrees reiterates the building high pressure ridge moving into the Pacific Southwest. By Friday, PoE shows widespread coverage of greater than 50% as confidence grows toward reaching triple digit temperatures. By the weekend, PoE of reaching 100 degrees ranges from 70% to 90%, while at the same time, PoE of 103 degrees is 50% or less across the San Joaquin Valley. Therefore, current thinking has the San Joaquin Valley less likely to enter a significant heat-wave this weekend as afternoon highs range from 99 to 103 degrees. Yet, with little change in the overall weather pattern, will see minimal change in temperatures as triple digits stick around for several days. Therefore, the San Joaquin Valley will see triple digit temperatures reaching into next Tuesday. The position the four-corners high will play a big factor in the transport of moisture into the region. Ensemble winds aloft maintain a southwesterly direction which will keep higher precip-water values east of Central California. With a lack of Monsoonal moisture pushing into Central California, convection will be inhibited across the Sierra Nevada as the region remains dry. While ensemble wind prognosis show only light breezy conditions developing each afternoon, minor fire weather concerns will exist due to the nature of how dry (especially Kern County) conditions are across the West. && .AVIATION... 00Z Update: 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...Molina aviation....McCoy weather.gov/hanford