457 FXUS66 KHNX 022312 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 412 PM PDT Mon Jun 2 2025 .UPDATE... Air Quality and Aviation Sections Updated && && .KEY MESSAGES... 1. Minor Heat Risk is expected in the San Joaquin Valley through Thursday before Moderate Heat Risk returns on Friday into the weekend. 2. There is a 15 to 25 percent chance for thunderstorms in the Sierra Nevada mountains each afternoon today through Wednesday, with the Storm Prediction Center issuing a General Risk for thunderstorms in the mountains for each of those days. 3. Breezy winds can be expected in the mountain and desert regions today, due to a disturbance located over the Southwest. && .DISCUSSION... A disturbance located over the California/Arizona border continues to bring in small amounts of moisture from the Gulf of California to the south, leading to increased chances of thunderstorms (15 to 30%) over the Sierra Nevada this afternoon. This disturbance along with a shortwave trough to the north has lead to reduced 500mb heights and slightly cooler temperatures compared to yesterdays highs. Though these temperatures will remain above normal, the Heat Risk is expected to be Minor today and through Thursday as the shortwave trough swings south into Central California. This will also keep afternoon thunderstorm chances elevated with Tuesday and Wednesday seeing a 15 to 25% chance for thunderstorm development. This disturbance will also cause increased winds along the Sierra crest and Mojave Desert today, though current forecasts have the wind gusts likely below Advisory criteria. Moving into Thursday and beyond, the larger trough that contained the shortwave trough will remain over California, however the energy contained within that trough is expected to be less when compared to the shortwave, leading to reduced thunderstorm chances after Thursday, though a 10 to 15% chance still exists in the afternoon that day and Friday for the Sierra Nevada. 500mb heights are also expected to increase Friday while the trough remains aloft, leading to a warming trend beginning that day. This is expected to continue through next weekend, causing Moderate Heat Risk to return to the Valley starting Friday and running through next Monday at least. && .AVIATION... 0Z Update: VFR conditions will prevail for the next 24 hours across the Central California Interior. Thunderstorm chances continue across the Sierra Nevada until 03Z Tue. There also is a 15-30 percent chance of thunderstorms between 18Z Tue and 03Z Weds. && .AIR QUALITY ISSUES... ISSUED: 06/02/2025 14:30 EXPIRES: 06/03/2025 23:59 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...EW aviation....JPK weather.gov/hanford