Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
504 FXUS66 KHNX 060901 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 201 AM PDT Mon Oct 6 2025 && .KEY MESSAGES... 1. Seasonable temperatures with dry conditions are expected through much of the upcoming week. There is a 30 to 40 percent probability to exceed 90 degrees Tuesday in the San Joaquin Valley. 2. A low pressure system will bring chances for precipitation to the area Friday and Saturday. There is a 40 to 50 percent probability for measurable rainfall in the Desert and Mountain areas, and a 20 to 30 percent probability for the San Joaquin Valley. 3. Colder air with the system brings a 30 to 40 percent probability for 1 inch or more of snowfall Friday into Saturday mainly for elevations above 10000 feet. && .DISCUSSION... A broad, longwave trough is currently making its way across the interior US this morning, with a localized low pressure system anticipated to become cutoff from the main flow, and sitting stationary off the California coast for Monday and Tuesday. Southwesterly winds associated with the low will cause a slight warming trend through midweek. Afternoon temperatures are expected to be near season averages, but with a 30 to 40 percent probability to exceed 90 degrees in the San Joaquin Valley on Tuesday. A breakdown of the low pressure system on Wednesday will result in more seasonable conditions as weaker flow sets up aloft. In the latter portion of the week, there is good agreement from ensemble clusters for a robust low pressure system to drop south from the Gulf of Alaska. Stronger winds around the center of the low will start a cooling trend into the weekend, with afternoon highs approaching five to eight degrees below average for this time of year. Also worth mentioning, current Hurricane Priscilla is expected from the National Hurricane Center to slide north along the coast of Baja California through the week, becoming a Tropical/Post-Tropical Cyclone into the weekend. While some uncertainty is present for the location and intensity of the system, ensemble guidance suggests some tropical moisture to entrain over southern California. Clusters show the majority of the moisture remaining to the south of our CWA, though there is still a 40 to 50 percent probability for measureable rainfall greater than 0.01 inches in the desert and mountain areas over 24 hours ending 5 AM Saturday. However, probabilities are 20 to 30 percent for the San Joaquin Valley. The relatively low chances are primarily due to the aforementioned system off the Pacific coast, which for now is projected to deflect tropical moisture into the desert southwest. Cooler moisture with this low has a 30 to 40 percent probability to result in an inch of snowfall in the central Sierra, primarily above 10000 feet. && .AVIATION... VFR conditions are expected through 00Z Tuesday. && .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... None. && $$ public/aviation...McCoy weather.gov/hanford