Fresno, California Weather Forecast Discussion

220
FXUS66 KHNX 190017
AFDHNX
Area Forecast Discussion
National Weather Service Hanford CA
417 PM PDT Thu Sep 18 2025
.KEY MESSAGES...
1. Flood Watch in effect until Friday evening due to Slight
(15-40 percent) risk of Excessive Rainfall across much of the
region today and in the Sierra Nevada tomorrow. There is a
marginal (5-15 percent) risk of Excessive Rainfall today in the
northern portion of the Valley and Sierra Nevada and tomorrow in
the east side of the Valley.
2. 15 to 30 percent chance of thunderstorms this afternoon
through Friday morning across much of the region. 10-20 percent
chance Friday afternoon in the Sierra Nevada and foothills, and
a 5-15 percent chance in the San Joaquin Valley, Kern County
mountains, and the Mojave Desert.
3. Temperatures rebound over the weekend into next week before
another cooldown midweek.
&&
.DISCUSSION...
This morning, showers began moving into our area from the
remnants of Tropical Storm Mario. However, as the center of the
low moves up the coast, it will bring more moisture into our
area later this afternoon and evening along with the chances of
thunderstorm. The rain amount from this storm especially
overnight and during thunderstorms had led to the issuance of
Flood Watches for most of the area through Friday evening. Burn
scars are the major concern due to the heavy rain. There is a 15
to 30 percent chance of thunderstorms from this afternoon to
Friday morning as the chances move from the Mojave to the Valley
to the Sierra Nevada. The heavy rain has led to a Slight risk of
excessive rainfall for most of the area.
Things begin to taper off Friday afternoon but the thunderstorm
chances will remain through the evening. The Sierra Nevada is
under a slight (15-40 percent) risk of excessive rainfall with
the eastern half of the Valley under a marginal (5-15 percent)
risk. Saturday through Monday, things dry out as temperatures
climb as a weak ridge develops and the trough moves west.
However, there remains a 5 to 15 percent chance of
thunderstorms over the Sierra Nevada. Ensembles diverge Monday
into the middle of next week regarding whether the cutoff low
that will remain in the Pacific to the west will be picked up by
a trough sliding in from the Pacific Northwest or if it weakens
and the trough slides well north across Washington.
&&
.AVIATION...
00Z Update:
Thunderstorm chances will creep in and will persist through 06Z
before primarily being over the mountains and Mojave desert. Lower
visibilities possible in heavier showers and lower clouds over the
mountains. Otherwise, VFR conditions will prevail for the next 24
hours.
&&
.AIR QUALITY ISSUES...
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...
Flood Watch through Friday afternoon for CAZ321-322-331>339.
Flood Watch from 2 PM PDT this afternoon through Friday
afternoon for CAZ304>316.
Flood Watch through Friday evening for CAZ317>320-323>330.
&&
$$
public...JPK
aviation....SM
weather.gov/hanford

NWS HNX Office Area Forecast Discussion