Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
338 FXUS66 KHNX 131745 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 1045 AM PDT Thu Aug 13 2026 && .KEY MESSAGES... 1. Potential for thunderstorms across the area again, ranging from 5 to 10% in the San Joaquin Valley and Mojave Desert up to 40% along the Sierra Nevada crest. 2. Threat of damaging wind from strong thunderstorms. 3. Isolated dry lightning presents elevated fire risk today for Sierra Nevadas. 4. Lake Wind Advisory for San Luis Reservoir from 5PM this afternoon until 2AM Friday morning. && .DISCUSSION... Morning guidance indicates our area is booked for one more day of monsoon moisture as the trough off the California coast pushes inland today. Compared to the more region- wide events yesterday and Tuesday, today`s primary threat will be along the Sierra Nevada crest and downwind into the Great Basin. The latest probabilistic run from the National Blend of Models (NBM) places the Sierra Crest under a 30-40% probability for thunderstorms with 20-25% probability down to around 2,000-3,000 feet. The main weather threat associated with today`s thunderstorms is lightning- initiated fires and brief damaging gusts in the Sierra Nevadas. The southwesterly flow transferring precipitable water (PWAT) into our area is noticeably weaker compared to the past couple days, indicative of lower probability for thunderstorms along the Coastal Range, the San Joaquin Valley, and Mojave Desert. Amongst these areas, short- term ensemble guidance and the NBM are in good agreement the friendly trough will hasten winds through Pacheco Pass later this afternoon. Thus, a Lake Wind Advisory for San Luis Reservoir is set to be in effect from 5PM this afternoon until 2AM Friday. By Friday afternoon, a transition to more neutral flow will significantly decrease the probability for thunderstorms in the Sierra Nevada, and will calm winds across the Coastal Range mountain passes. The entire forecast area looks set for a pleasant weekend, with San Joaquin Valley highs in the upper 80s to low 90s and mid-to-upper 90s in the Mojave Desert. A slight warmup is expected later next week as the region comes under the influence of high pressure. && AVIATION... VFR conditions prevailing for San Joaquin Valley (SJV). Scattered to broken cloud cover above 10,000 feet along foothills of eastern SJV, Sierra Nevada, and Kern County desert and slopes. Region wide threat of thunderstorms, with greatest probability (30-40%) along the Sierra Nevada crest until 03Z Thursday. Lower (5-10%) probabilities in the Mojave Desert and San Joaquin Valley. MVFR to high-end IFR conditions possible within thunderstorms from decreased visibility and cloud ceilings. && .FIRE WEATHER... Latest Storm Prediction Center (SPC) Convective Outlook highlights the Sierra Nevadas of Madera County and northward as under an isolated risk of dry lightning strikes. Combined with cured fuels, any lightning strikes outside thunderstorm precipitation cores have a high probability of initiating new fires. && .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...Lake Wind Advisory from 5 PM this afternoon to 2 AM PDT Friday for CAZ300. && $$ public...Daer aviation....McCoy weather.gov/hanford