Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
372 FXUS66 KHNX 242254 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 354 PM PDT Mon Jun 24 2024 && .KEY MESSAGES... 1. Temperatures will be around 10- degrees above average again on Monday with widespread triple digit highs across the lower elevations. A Heat Advisory remains in effect through Tuesday morning. 2. Above average temperatures will continue this week, with 100 degree heat persistent for many locations through Wednesday. 3. There is a 10 to 30 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 remains over central California, with the center currently located over the southwestern United States. The subsiding air underneath the ridge is continuing to bring triple digit heat to the San Joaquin Valley, around ten degrees above seasonal averages for this time of year. Because of these warmer temperatures, a Heat Advisory remains in effect through Tuesday morning. Ensemble guidance from the National Blend of Models expresses a 70 to 80 percent probability to exceed 100 degrees in the San Joaquin Valley this afternoon, with a 60 to 80 percent probability Tuesday afternoon; however, the northern San Joaquin Valley, including Madera and Merced, has a 40 to 60 percent probability Tuesday. Moisture from the former tropical system Alberto is being wrapped around the upper level high, bringing scattered showers to the San Joaquin Valley from the southwest this afternoon. The propagating moisture is expected to continue cascading across central California tomorrow, bringing a chance for thunderstorms to the Sierra Nevada Tuesday afternoon. Probabilistic guidance suggests 20 to 30 percent for thunderstorms along the Sierra crest from Yosemite National Park to Kings Canyon and Sequoia National Park. Some stronger thunderstorms are possible, with the major hazards being dangerous cloud to ground lightning, small hail, and stronger wind gusts near 40 miles per hour. The aforementioned high pressure system is anticipated to weaken slightly into the midweek as an upper level trough passes through the Pacific Northwest region. This will result in a slight cooling trend across central California through next weekend. Guidance from the NBM expresses less than a 30 percent probability for temperatures to exceed 100 degrees each day through Sunday. This cooling trend will bring temperatures close to season normals. However, while temperatures may be cooler, the increased pressure gradient between the trough to the northwest and the ridge to the southeast will increase winds to the region. This parameter, coupled with relative humidity below 20 percent, will result in at least a minor risk for grassland fires across the region. Cluster analysis points towards another ridge building over our area into July, with long term probabilities showing at least a 60 percent probability for triple digits across the San Joaquin Valley beginning July 2nd. && .AVIATION... MVFR conditions possible around scattered showers along the crest and surrounding foothills of the Sierra Nevada through 02Z. MVFR conditions are possible again Tuesday afternoon along the Sierra Nevada crest. Otherwise, VFR conditions will prevail across the central California interior for the next 24 hours. && .AIR QUALITY ISSUES... ISSUED: 06/23/2024 15:54 EXPIRES: 06/24/2024 23:59 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... Heat Advisory until 11 AM PDT Tuesday for CAZ300>317-319-321- 332. && $$ public/aviation...SM IDSS..............EW weather.gov/hanford