textproduct: San Joaquin Valley

KEY MESSAGES

1. A colder system is expected to move through the region early this morning, with snow levels dropping down to around 5000 feet as the system passes through. Moderate to heavy precipitation is expected again with this storm, mainly in the Sierra Nevada and its foothills.

2. A weaker system may bring some more precipitation to the region again by Thursday into Friday.

3. The region looks to finally dry out by the weekend, though fog formation is possible during that time due to the abundant amount of moisture in the Valley at the moment.

DISCUSSION

Another trough is expected impact the region this morning, with an open trough coming down from the north and pulling in cold air from Canada, leading to a cooler system and lowered snow levels. These levels are currently forecast to start at 6000 feet before dropping to around 5000 feet as the system moves through, though they may lower further to around 4500 feet after the passage of the front. There is also a Marginal Risk (at least 5%) of excessive rainfall from the West Side Hills to the Sierra Nevada foothills, and into the Mojave Desert. The majority of the precipitation is expected to fall through this evening, with lingering light precip through Tuesday afternoon.

The rain takes a bit of a break on Wednesday, though with the amount of moisture already in the area, fog formation in the Valley is not out of the question, depending on how close the mixing layer is to the surface to keep it from forming. A weaker system is expected to move through the region by Thursday, though this trough may only bring some light precip to our CWA, with it lasting until Friday. Then the region will have a chance to dry out this weekend, with the cut-off trough from the Thursday system moving to our south and a ridge building in from the Pacific Ocean. This may lead to fog formation again with the same reason as before.

AVIATION

VFR conditions will prevail for the next 24 hours, with MVFR conditions possible due to rainfall and lowered ceilings through at least the next 24 hours.

AIR QUALITY ISSUES

On Monday November 17, 2025, Fireplace/Wood Stove Burning Status is: Burning Discouraged in Fresno, Kern, Kings, Madera, Merced, and Tulare Counties, and Kern (Greater Frazier Park Area) and Sequoia National Park and Forest.

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 through this afternoon for CAZ317>322-332-333. Winter Weather Advisory until 10 PM PST this evening for CAZ323-326>331.