Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
673 FXUS66 KHNX 180930 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 230 AM PDT Wed Sep 18 2024 .KEY MESSAGES... 1. There is a 60 percent probability for 0.10 inch or more of rainfall in the San Joaquin Valley on Thursday and a 15 to 30 percent probability for 0.25 inch or more. 2. There is a 50 to 85 percent probability for 0.25 inch or more of rainfall across the Sierra Nevada from Fresno County north and less than a 50 percent probability south of Fresno County. There is a 25 percent probability for 0.50 inch or more of rainfall in Yosemite Valley on Thursday. 3. There is a 65 percent probability for 1 inches or more of snowfall at Tioga Pass on Thursday and a 39 percent probability for 2 inches or more. Snow levels will be above 9,000 feet. 4. There is up to a 35 percent chance for thunderstorms across the Sierra Nevada on Thursday, highest around Yosemite NP. There is a 10 to 15 percent chance for thunderstorms across the San Joaquin Valley on Thursday and areas from Fresno County northward on Wednesday. 5. Temperatures will be 10 to 15 degrees below normal through Thursday before a weekend warmup. && .DISCUSSION... The unsettled weather pattern continues across the Central California Interior as yet another disturbance is ready to enter the region. Satellite and upper-air analysis show the center of the next disturbance just off the Pacific Northwest Coast-line and drifting south. Regional Doppler radars show precipitation over Northern California which will move over Central California later today. In the meanwhile, a strong northwest wind flow aloft will keep temperatures below normal as afternoon highs stay in the lower 80s. Evens as winds aloft reach speeds of 25 to 30 mph, cool air has reached to Kern Desert as indicated in the relaxed surface pressure gradients. Currently, the KSFO to KLAS gradients sits at around 5mb. Therefore, will not expect strong surface winds today along the Eastern Slopes of the Tehachapi Range toward Mojave. Ensemble timing has the precipitation enters the district this afternoon with widespread precipitation this evening. Ensembles have a good handle on the current situation of moving another disturbance over Central California later in the afternoon. Based on the trajectory of the disturbance hugging the coast during the day, precipitation chance are better across the Sierra Nevada than the San Joaquin Valley around mid-day. Between Noon and 2:00 PM PDT, the Sierra Nevada will have 20-30 percent chance of Measurable Precipitation, the San Joaquin Valley will remain between 5-10 percent during the same period. In addition, Probability of Thunder will also range between 15-25 percent across the Sierra Nevada. Closer to 5:00 PM PDT, Probabilities of Measurable Precipitation (PoP) across the Sierra Nevada rises to 60-80 percent while Valley-wide PoP remains below 30 percent. Ensemble upper-air analysis show the upper low moving across Central California on Thursday. This timing increases the chances of unsettled weather and is covered by a Winter Weather Advisory. Due to the elevation of expected snowfall the snowfall probabilities for the favor area of Tioga Pass are listed as follows: Tioga Pass (Yosemite) 24 Hour snowfall 65% >1 inch 39% >2 inches 4% >4 inches Furthermore, Probability of Thunder for Central California goes up to near 30-35 percent during the afternoon with more coverage into the Northern San Joaquin Valley. PoP for the Valley jumps up to near 60 percent with minimal change in temperatures. Friday will see lingering showers as moisture banks-up along the south end and east side along the foothills. The ridge pattern returns this weekend with drying and warming going into early next week. Probability of Exceedance of reaching 100 degrees moves up to around 20-30 percent next Tuesday. While summer will end on Sunday, 100 degrees still has one last chance before September ends. && .AVIATION... Areas of MVFR and local IFR visibilities near wildfires. Mountain obscurations over the Sierra Nevada after 18Z Wednesday due to RA/SN showers. Otherwise, VFR conditions will prevail across the central CA interior over 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... Winter Weather Advisory from 2 PM this afternoon to 8 PM PDT Thursday for CAZ323-326-328-330. && $$ public...Molina aviation....DCH weather.gov/hanford