textproduct: San Joaquin Valley

KEY MESSAGES

1. A Flood Watch is in effect for the Sierra Nevada below 9,000 feet and foothills, mainly Yosemite, as well as Mariposa and Madera Counties until Monday. The Flood Watch will then cover all portions of our forecast area from Tuesday afternoon until Friday afternoon.

2. Chances for precipitation, with moderate to heavy amounts at times, continue for the Sierra Nevada and its foothills from Fresno County northwards through Tuesday morning.

3. A second, stronger system is expected to arrive by Tuesday afternoon, with a moderate risk for heavy precipitation throughout Central California, and a moderate risk for heavy snow in the Sierra Nevada expected from Christmas Eve through Friday of next week.

DISCUSSION

Showery weather is largely north of our forecast area, except it has been passing since this afternoon over the far northern portions of Yosemite, based on latest radar imagery. Additional showers may fluctuate a little bit south later tonight into Monday morning, but still confined to northern portions of our area, mainly north of Fresno County. There are slight (15-20%) chances for precipitation to begin early Tuesday, but greater probabilities begin late Tuesday afternoon. Most locations have some chance of precipitation by then, including into the Kern County desert. Also, during Tuesday evening and the overnight hours into Wednesday, gusty southerly winds arrive along with the initial surge of precipitation. The strongest gusts are shown over the higher terrain along the west side of the San Joaquin Valley to the Grapevine. Advisory level gusts (40-50 mph) have a greater chance to materialize, except some isolated gusts near 60 mph or a little stronger are not out of the question.

The bulk of the precipitation is in store from late Tuesday night until Wednesday night, although copious amounts will also occur during into Christmas Day into the following evening as another surge passes over our region. Probabilities for locations to exceed one inch per 24 hours:

Ending Wednesday 4 PM

San Joaquin Valley - 60-70%, except 40-50% in rain shadowed areas Coastal Ranges - 80-90% Sierra foothills - 90 to near 100% (amounts exceeding 2 inches at 70-80 percent) Sierra Nevada - 90 to near 100% (and 80-90% chance to exceed 2 inches including locations expecting snowfall) Kern County desert- 60-70%

Ending Christmas Day 4 PM

San Joaquin Valley- 50-60%, except 30-40% in rain shadowed areas Coastal Ranges - 50-60% Sierra foothills - 90 to near 100% northern half, 60-70% southern half Sierra Nevada - 90 to near 100% mainly north, otherwise 60-70% Tulare & Kern Counties Kern County desert - 25-35%

Snow accumulations above 6,000 feet in the Sierra Nevada will be measured in feet, with several feet above 8,000 feet. A 30-40 chance of at least an inch of snow to reach near 6,000 feet exists for portions of Kern County, including over the mountains from south of Lake Isabella to the Frazier Park area on Thursday night into Friday. Thus, at least at this time, the main issues over the passes in Kern County will be winds and heavy rain.

The other thing to watch out for will be gusty winds in the Kern County desert and the adjacent slopes from Wednesday until Friday. Probabilities for 45 mph gusts for a 24 hour period between Wednesday night to Thursday night peak at 60-70%.

By Friday, the cold front passes, although an upper-level trough remains situated along the West Coast into the weekend that will produce lingering showers. Snow levels will lower a bit during this period (right now at around 5,000 feet for Saturday until next Sunday), although we will monitor for the potential of any impacts to the passes in Kern County. Above average precipitation is still favored in our area beyond next weekend. The 6-10 day outlook shows about a 40 to 50 percent chance, while the 8-14 day outlook lowers to 33-40 percent. A slight tilt in the odds towards above average temperatures is shown for both periods.

AVIATION

MVFR to IFR ceilings due to precipitation over the Sierra Nevada and adjacent foothills from Fresno County northward are expect over the next 24 hours. MVFR conditions are expected at times for mainly northern portions of the San Joaquin Valley from 09Z-18Z Monday due to -SHRA. Otherwise, VFR conditions will prevail over the next 24 hours.

AIR QUALITY ISSUES

On Monday December 22 2025, Fireplace/Wood Stove Burning Status is: No Burning Unless Registered in Fresno, Kern, and Madera Counties. Burning Discouraged in Kings, 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 from Tuesday afternoon through Friday afternoon for CAZ300>317-319>322-327>339. Flood Watch through Friday afternoon for CAZ318-323>326. Winter Storm Warning until 4 PM PST Friday for CAZ323. Winter Storm Watch from Tuesday afternoon through Friday afternoon for CAZ326>331.