Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
707 FXUS66 KHNX 300530 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 1030 PM PDT Tue Jul 29 2025 .UPDATE... Aviation Section Updated && && .KEY MESSAGES... 1. There is a 5 to 20 percent chance for showers and thunderstorms to develop across the Sierra Nevada Crest today and Wednesday afternoon, with the greatest chances in the high country of Yosemite National Park. 2. Temperatures return to near or slightly above season averages this week with an increase in fire risk due to lowering RH values and breezy conditions. && .DISCUSSION... The synoptic pattern to start the week is continuing today with an upper level trough extending south along the Pacific Coast from the Gulf of Alaska and a strong area of high pressure over the southern Plains region. Southwest flow over central California resulting from this pattern is causing warmer, but slightly below average temperatures this afternoon along with gusty winds in the typical wind-prone areas such as Pacheco Pass, Lake Isabella, and the Mojave Desert Slopes. Moisture streaking in the mid levels over the area is expected to condense along the Sierra crest this afternoon, with a slight chance (5 to 15 percent) to produce thunderstorms, mainly in the high country of Yosemite National Park. Chances improve to 10 to 20 percent tomorrow as a shortwave perturbation within the longwave trough passes through central California, causing a sharp increase in positive vorticity which will improve upward vertical motion and allow for better convective potential over the Sierra. However, much like the previous few days, the greatest chances will be in the higher elevations in and around Yosemite National Park. As the week progresses, the aforementioned area of high pressure is expected to slide westward over the Desert Southwest region, causing a shift in the upper level flow to due west. As a result, temperatures will near season averages in the upper 90s for the San Joaquin Valley, with an additional 20 to 40 percent chance for afternoon highs to reach over 100 degrees. && .AVIATION... 06Z Update: VFR conditions are expected in the San Joaquin Valley for the next 24 hours. A 5 to 20 percent chance of thunderstorms will exist across the Sierra Nevada Crest from Yosemite to Tulare County through 03Z Wednesday. && .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...SM aviation....JPK weather.gov/hanford