Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA
Issued by NWS San Joaquin Valley, CA
540 FXUS66 KHNX 030955 AFDHNX Area Forecast Discussion National Weather Service Hanford CA 155 AM PST Wed Dec 3 2025 .KEY MESSAGES... 1. Fog development will continue overnight into Wednesday morning across the San Joaquin Valley. 2. A dry disturbance will introduce increasing winds across the deserts and mountain peaks on Wednesday and Thursday; cold morning lows also anticipated for the high Sierra. && .DISCUSSION... Low stratus cloud cover continues over the central valley this afternoon after lifting from the valley surface. Stagnant and subsiding air aloft will cause rising moisture from the valley to settle in the low levels of the atmosphere, gradually improving visibilities at the surface. However, a knock-on effect will need to occur to remove this stratus cloud deck where warmer surface temperatures cause the clouds to erode, which will in turn lead to more of the surface receiving sunlight, causing warmer temperatures, and so on.Clearer skies yesterday came about with help from stronger low level winds mixing out the saturated air, which will likely need to happen again today, given that the persistence of the stratus deck has extended further than model guidance indicated. Without clearing, we can expect this cloud deck to continue into tomorrow morning. This being said, a shortwave upper level trough is expected to make its way through the Great Basin this afternoon through early Thursday morning, with the vorticity maximum of the trough tracking due north/south over central California. The vortmax and increased winds at the center of the troughs axis may allow for enough low level mixing to occur over the valley areas to cause clearer conditions to prevail into Wednesday, however these elements will need to extend into the lower levels in order to do so. More definitive impacts from the incoming trough will be seen in the higher elevations of the region. Cold, dry northerly air will be entrained into this area, causing dangerously cold conditions Wednesday and Thursday mornings. Minimum temperatures above 9000 feet are expected to approach 10 degrees Fahrenheit, but with the added effect of the wind, apparent temperatures are projected to fall into the negatives. Due to this, a Cold Weather Advisory has been issued for the Sierra Nevada above 9000 feet. Starting in the late week, more benign conditions will return due to the influence of a high pressure ridge over the eastern Pacific. The high will direct more significant weather further north and east of central California, while prolonging the stagnant conditions currently observed over the region. && .AVIATION... IFR/LIFR visibilities are expected at all TAF sites for the next 24 hours. Between 12Z and 19Z Wednesday, VLIFR conditions have a 40% to 60% chance of occurring in dense fog. Conditions are expected to see brief improvements into MVFR conditions between 22Z Wednesday and 03Z Thursday. && .AIR QUALITY ISSUES... On Wednesday December 3 2025, Fireplace/Wood Stove Burning Status is: No Burning Unless Registered in Fresno, Kern, Kings, Madera, Merced, and Tulare Counties. Burning Discouraged in Kern (Greater Frazier Park Area) and Sequoia National Park and Forest. && .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... Dense Fog Advisory until 11 AM PST this morning for CAZ305>307- 309>312-314-315. Cold Weather Advisory until 9 AM PST Thursday for CAZ323- 326>328-330-331. && $$ Aviation....Molina weather.gov/hanford