Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
457 FXUS66 KHNX 190901 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 201 AM PDT Thu Sep 19 2024 .KEY MESSAGES... 1. There is a 40 to 60 percent probability for 0.10 inch or more of rainfall in the San Joaquin Valley on Today and a 10 to 25 percent probability for 0.25 inch or more. 2. There is a 50 to 80 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 rainfall in Yosemite Valley on Today. 3. There is a 49 percent probability for 1 inch or more of snowfall at Tioga Pass on Today and a 24 percent probability for 2 inches or more. Snow levels will be around 9,000 feet. 4. There is a 30 to 40 percent chance for thunderstorms across the Sierra Nevada and West Side Hills on Today, highest around Yosemite NP. There is a 15 to 20 percent chance for thunderstorms across the San Joaquin Valley and West Side Hills on Thursday. 5. Temperatures will be 10 to 15 degrees below normal through Thursday before a weekend warmup. There is a 30 to 50 percent chance of High temperatures reaching 100 degrees by Tuesday. && .DISCUSSION... Isolated showers continue across the Central California Interior as the associated upper low moves further down the coast this morning. Satellite and upper-air analysis show the center of the disturbance just off the Central Coast and showing a trajectory toward Santa Barbara. Being that the disturbance will take a coastal hugger track, higher precipitation values will remain west of the Coastal Range with up-slope precipitation dominating Central California. This means mountainous terrain will be favored for any significant precipitation values. Therefore, the Valley, north of Fresno County will have a difficult time receiving more than 0.01 inches of rain. The strong west to northwest wind flow aloft will keep temperatures near their Wednesdays values as little change is expected today. Evens as winds aloft reach speeds of 25 to 30 mph, cool air resides over the Kern Desert as indicated in the relaxed surface pressure gradients. Currently, the KSFO to KLAS gradients sits at around 4mb. Therefore, will not expect strong surface winds today. Being on the right-side of the upper low, instability will be favored across the district as thunderstorm development will be possible this afternoon. Upper low expected over Southern California by Friday with lingering showers over Central California. Afterward, high pressure returns as the region will see another round of warm temperatures. Ensembles have a good handle on the current situation of moving another disturbance along the California Coast today. 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. This is noted in both Probability of Measurable Precipitation (PoP) and Probability of Thunder (PoT). Both show PoP of up to 80 percent for the Mountains and near 60 percent for the Valley today. PoT is similar with 30 to 40 percent over the Sierra and 25 percent or less over the Valley. With snow level near 9,000 feet, unsettled weather 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 49% >1 inch 24% >2 inches 3% >4 inches 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 30-50 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 obscuration over the Sierra Nevada after 18Z Today due to rain and snow 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... Flood Watch from 5 AM PDT early this morning through this evening for CAZ308-313-336. Winter Weather Advisory until 8 PM PDT this evening for CAZ323- 326-328-330. && $$ Operations......Molina Support/IDSS....JPK weather.gov/hanford