Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
037 FXUS66 KHNX 182111 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 211 PM 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 rainfall in Yosemite Valley on Thursday. 3. There is a 49 percent probability for 1 inch or more of snowfall at Tioga Pass on Thursday and a 24 percent probability for 2 inches or more. Snow levels will be around 9,000 feet. 4. There is up to a 30 percent chance for thunderstorms across the Sierra Nevada, San Joaquin Valley, and West Side Hills on Thursday, 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. && .DISCUSSION... The low pressure system that has brought cooler temperatures to the region and will bring rain and snow to the region tomorrow is sitting just off the coast of Northern California. It will begin tracking southward along the California coast. Temperatures will continue to be 10-15 degrees below normal for this time of the year. There remains a chance of some showers throughout the San Joaquin Valley today alongside a 20 to 25 percent chance of thunderstorms along the Sierra Crest. However, most of the precipitation looks to fall tomorrow through tomorrow evening. Elevations 9,000 feet and above could see 2 to 5 inches of snow tomorrow. Tioga Pass, in particular, looks to see up to 4 inches of snow. Probabilities for snow in Tioga Pass are as follows: 49 percent for one or more inches, 24 percent chance for two or more inches, and three percent for four or more inches. Due to the early nature of the snow associated with this low pressure system, a Winter Weather Advisory has been issued for areas above 9,000 feet from 2pm today through 8pm tomorrow night. People traveling in these areas should prepare for wintry road conditions. Alongside this snow will be rain in elevations below 9,000 feet. There is a 50 to 85 percent probability of 0.25 inches or more of rainfall across the Sierra Nevada north of Fresno. There is also a 60 percent probability of 0.10 inches or more of rainfall for the San Joaquin Valley. Much of this rain and precipitation looks to fall Thursday through Thursday afternoon and into the evening. Additionally, there is the chance for widespread thunderstorms throughout the Sierra Nevada, San Joaquin Valley, and West Side Hills tomorrow as well. Highest probabilities for thunderstorms are in the Sierra Nevada, at 30 percent, though there is a 15 to 20 percent chance of thunderstorms throughout most of the San Joaquin Valley. In particular, model ensemble guidance favors a 20 to 25 percent chance of thunderstorms in the West Side Hills. Because of a burn scar in this area, the Hurricane Burn Scar, a Flood Watch has been issued due to models favoring training thunderstorms moving across the area frequently throughout the day. These thunderstorms could lead to high rainfall rates and localized flooding in the warned area. This Flood Watch is valid from 5am tomorrow morning through 11pm tomorrow night. People within the Flood Watch should closely monitor any weather alerts should any flood warnings need to be issued. On Friday, the low pressure system will sweep east across California and then move out of the area. With the low pressure system out of the area, ridging will begin to take place, warming the forecast area back up to near normal temperatures and bringing dry conditions to the area through at least the weekend. && .AVIATION... Areas of MVFR and local IFR visibilities near wildfires. Mountain obscurations over the Sierra Nevada after 18Z Wednesday due to rain and snow showers. Otherwise, VFR conditions will prevail across the central CA interior over the next 24 hours. && .AIR QUALITY ISSUES... ISSUED: 09/17/2024 14:53 EXPIRES: 09/18/2024 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... Flood Watch from late tonight through Thursday evening for CAZ308-313-336. Winter Weather Advisory until 8 PM PDT Thursday for CAZ323-326- 328-330. && $$ public/aviation....AS PIO/IDSS...........BSO weather.gov/hanford