Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
514 FXUS66 KHNX 222130 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 230 PM PDT Sat Jun 22 2024 && .KEY MESSAGES... 1. Temperatures will rise around 10 to 15 degrees above average this afternoon and Sunday with widespread triple digit highs across the lower elevations. A Heat Advisory is in effect through Monday morning. 2. There is a 50 to 80 percent probability for maximum temperatures of 105 degrees or above across most of the San Joaquin Valley Saturday and Sunday afternoons. 3. Above average heat will continue into the middle of next week, with 100 degree heat persisting for many locations. 4. There is a 10 to 20 percent probability for thunderstorms Tuesday afternoon along the Sierra Nevada crest from Yosemite National Park to Kings Canyon and Sequoia National Park. && .DISCUSSION... An upper level high pressure ridge has begun to build over central California this morning from the east that will dictate the synoptic pattern through much of next week. Subsiding air aloft from the ridge and minimal surface winds will drive temperatures past 105 degrees in the San Joaquin Valley today and Sunday, and past 100 each day through Wednesday. A Heat Advisory remains in effect due to these warmer temperatures for much of the area under 2500 feet. High resolution ensemble guidance from the HREF gives the following probabilities to reach 105 degrees this afternoon for various locations of the San Joaquin Valley. Saturday --------------- Delano 80% Hanford 80% Lemoore 80% Merced 80% Bakersfield 70% Madera 70% Porterville 70% Fresno 60% Visalia 60% Reedley 50% Sunday --------------- Delano 80% Hanford 80% Madera 80% Visalia 80% Lemoore 70% Merced 70% Porterville 70% Bakersfield 60% Fresno 60% Reedley 60% Probabilities from the National Blend of Models ensemble show similar chances for 100 degrees in the San Joaquin Valley between Monday and Wednesday before backing down to less than 30% for Thursday and Friday. The cooling trend is primarily due to a weak upper level trough moving through the region as the center passes through the Pacific northwest. The trend is unlikely to continue into next weekend as cluster analysis projects another strong upper level ridge propagating over central California and leading to another moderate probability (40 to 60 percent) for triple digit heat. However, during the early part of next week, moisture from the remnants of former tropical storm Alberto will be picked up by the aforementioned upper level ridge. The anticyclonic flow around the center of the upper level pattern will push this moisture into central California from the south. The combination of increased relative humidity in the atmosphere and warmer surface temperatures extending from the valley and foothill areas will bring a chance for convective development to the Sierra Nevada Tuesday. The NBM expresses a 10 to 20 percent probability for thunderstorms in the area stretching from Yosemite National Park to Sequoia and Kings Canyon National Park through the afternoon and evening periods. A few stronger thunderstorms may be possible with the major threats being dangerous cloud to ground lightning, small hail, and wind gusts up to 40 miles per hour. && .AVIATION... VFR conditions will prevail across the Central CA interior for the next 24 hours. && .AIR QUALITY ISSUES... ISSUED: 06/21/2024 14:28 EXPIRES: 06/22/2024 23:59 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... Heat Advisory until 11 AM PDT Monday for CAZ300>317-319-321- 332. && $$ public...SM aviation....SM weather.gov/hanford