


Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
418 FXUS66 KHNX 130810 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 110 AM PDT Mon Oct 13 2025 && .KEY MESSAGES... 1. Winter Storm Warning in effect from 11 AM Monday through 5 PM Wednesday. 2. Flood Watch in effect from 5 PM Monday through 5 PM Tuesday for the Sierra Nevada foothills. 3. Portions of the Sierra Foothills and the Valley is under a Marginal (5-15 percent) Risk of Excessive Rainfall Monday and Tuesday. 4. There is a 5 to 30 percent chance of at least 18 inches of snow between 6,000 and 7,000 feet and a 60 to 85 percent chance of at least 18 inches of snow above 7,500 feet through 5 PM Wednesday. 5. The San Joaquin Valley has a 35 to 75 percent chance of at least an inch of rain in 24 hours ending Tuesday at 5 PM. The Sierra foothills have a 25 to 65 percent chance of at least 2 inches of rain in 24 hours ending at 5 PM Tuesday. 6. Drier and calmer conditions will prevail Thursday into the weekend before another trough slides in next Monday. && .DISCUSSION... Satellite imagery this morning has the trough sliding in from the Pacific Northwest with an outer band moving through at about 1 in the morning Pacific time. Latest model ensembles have shown this trough to be deeper than the one from last week. In addition, the latest ensembles are in strong agreement of a near 90 percent chance of Integrated Water Vapor Transport values of at least 250 kg/(m*s). In addition, temperatures will continue to drop with this storm which will lower snow levels to about 5,500 to 6,000 feet. This combination of high moisture values and cold temperatures have led models to have a 5 to 30 percent chance of at least 18 inches of snow between 6,000 and 7,000 feet and a 60 to 85 percent chance of at least 18 inches of snow above 7,500 feet through 5 PM Wednesday. Thus, we have a Winter Storm Warning in effect from 11 AM this morning through 5 PM Wednesday. There also is a 6 percent chance of a trace of snow along Interstate 5 through Tejon Pass through Wednesday evening. In the Valley, we are looking at a 35 to 75 percent chance of at least an inch of rain in 24 hours ending Tuesday at 5 PM. But, a Flood Watch is in effect for the foothills from 5 PM Monday through 5 PM Tuesday as there is a 25 to 65 percent chance of at least 2 inches of rain in 24 hours ending at 5 PM Tuesday. The major concern with the rain is the resulting flooding and debris flows at the burn scars. As the trough moves away late Wednesday into Thursday, a small ridge begins to build to the west. This ridge will gradually slide into the area over the weekend bringing temperatures back up. However, model ensembles agree another trough will slide in on Monday of next week. && .AVIATION... VFR conditions are expected to prevail until 21Z Monday. After 21Z, MVFR to IFR conditions begin to appear in the mountains in showers and low clouds, while the Valley could also see lower visibilities in heavier showers. There is a 5 to 20 percent chance of thunderstorms beginning at 0Z Tuesday for the Valley and Sierra Nevada through 0Z Wednesday. && .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 this afternoon through Tuesday afternoon for CAZ318-320-322-324-325-332-333. Winter Storm Warning from 11 AM this morning to 5 PM PDT Wednesday for CAZ323-326>331. && $$ JPK weather.gov/hanford