Trimmer, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

572
FXUS66 KHNX 180050
AFDHNX

Area Forecast Discussion
National Weather Service Hanford CA
450 PM PST Wed Dec 17 2025

.UPDATE...
Update to both the Aviation and Air Quality Sections to include
the latest information.

&&

.KEY MESSAGES...

1. A significant pattern change is expected to take place by
this weekend with precipitation likely for the Sierra Nevada and
its foothills from Fresno County northwards.

2. A second, stronger system is expected to follow the weekend
system by Tuesday, with a moderate risk for heavy precipitation
throughout Central California, and a high risk for heavy snow
in the Sierra Nevada expected from Christmas Eve through the
26th next week.

&&

.DISCUSSION...
A weak system to the north of our CWA is causing partial
clearing in the northeastern San Joaquin Valley, as of the most
recent satellite imagery. This clearing may continue throughout
the day, though it is uncertain that the clearing will continue
throughout the Valley. Fog is likely to reform during the
overnight hours in the cleared areas.

After a brief period of zonal flow, another system is expected
to come in slightly further south and bring some light to
moderate rainfall in the Sierra Nevada and its Foothills this
weekend. The snow levels with this system are unusual for this
time of year, with elevations of 8500 to 9500 feet expected over
the course of the system, though they will likely lower to
around 8000 feet after the main front has placed through.
Rainfall is expected mainly to the north of Tulare County,
concentrated in the Sierra Nevada and the Foothills. A small
amount of rain may make it into the Valley as well, mostly in
the northeastern portion of it.

A more significant system is expected to move through Central
California directly instead of to the north of the Valley. This
system is likely to bring large amounts of precipitation over
the course of a few days, mainly from December 24th through the
26th. While this forecast is more than 7 days out, the
confidence in the system occuring has been increasing for the
last few days due to the consistency in the ensemble models to
have this system occuring at that time period and that
intensity. Current outlooks from the Climate Prediction Center
have a moderate risk for heavy rainfall throughout our CWA from
the 24th through the 26th, and in the same time frame, a high
risk for heavy snowfall in the Sierra Nevada. The current snow
level forecasts for this time period has elevations of 7000 to
8000 feet, which is still higher than would be normally seen at
this time of year. This may lead to flooding concerns for the
Sierra Nevada as rain will likely fall below 7000 feet instead
of snow as would normal occur during December.

&&


.AVIATION...
IFR to LIFR ceilings and visibilities are expected to prevail for
much of the San Joaquin Valley during the next 24 hours, with a 40
to 50 percent chance of VLIFR in dense fog between 09Z and 12Z
Thursday. IFR to LIFR conditions will also persist in the
coastal ranges, Sierra foothills, and the Kern County mountains
due to low clouds. Otherwise, VFR conditions will prevail in the
Sierra Nevada and in the Kern County mountain and desert areas
over the next 24 hours.

&&

.AIR QUALITY ISSUES...
On Thursday December 18 2025, Fireplace/Wood Stove Burning
Status is: No Burning Unless Registered in Fresno, Kern, Madera,
and Merced Counties. Burning Discouraged in Kings, 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...
Wind Advisory until 4 AM PST Thursday for CAZ337>339.
&&

$$

public/aviation....EW

weather.gov/hanford