Valley Lake Ranchos, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

746
FXUS66 KHNX 272256
AFDHNX

Area Forecast Discussion
National Weather Service Hanford CA
356 PM PDT Tue May 27 2025

.UPDATE...
All sections have been updated.

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.KEY MESSAGES...
1. A Heat Advisory has been issued for the San Joaquin Valley,
Kern River Valley, lower Sierra Foothills, and West Side Hills
valid from 11 AM Friday through 7 AM Sunday.

2. Widespread Moderate to Major Heat Risk is expected across
the lower elevations of the region.

3. Relative humidity will gradually decrease through the week as
temperatures warm. Widespread 15 to 20 percent minimum RH is
expected across the San Joaquin Valley, and as low as 5 to 10
percent for the Kern County Desert and Mountains.

4. Mountain thunderstorms are possible this afternoon, with
potential for additional storms on Sunday.


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.DISCUSSION...
A ridge of high pressure is expected to gradually build in and
strengthen over the western United States this week, leading to
a warming trend before the weekend. The warming trend will be
enhanced by a cutoff upper level low pressure system that will
be moving into a fixed position off the coast of Baja California
Wednesday into Thursday. The flow around the low pressure
system is expected to drive warm, dry air into central
California from the desert Southwest region. Fridays
temperatures across the San Joaquin Valley have a 45 to 80
percent chance to exceed 100 degrees, with the greatest of these
chances being in the southern and western valley areas. These
probabilities increase on Saturday to a 70 to 100 percent
chance across the entire valley, and there is a 30 to 70 percent
chance for afternoon highs to exceed 105 degrees. These
temperatures are up to 20 degrees above average for this time of
year, and have a moderate to major risk for heat-related
illnesses for much of the population. Due to the conditions
listed above, a Heat Advisory has been issued for the San
Joaquin Valley and lower elevations of the Sierra Foothills.

While this heat is anomalous for this time of year, a cooldown
to below average temperatures is favored early next week as a
strong upper level trough drops southward along the Pacific
Coast. The dynamic flow around the trough will propagate winds
from the northwest, resulting in near-average temperatures on
Monday, and below average temperatures by Tuesday. The
approaching trough and receding cutoff low have the potential to
lift moisture over the Sierra Sunday afternoon, causing a slight
chance for thunderstorms to develop. Any storms that develop
bring a risk for lightning-induced fires as fuels are drying in
this area. The approaching trough may enhance the potential risk
by driving stronger winds across the Sierra crests and in the
Mojave Slopes.

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.AVIATION...
0Z Update:
There is a 5 to 15 percent chance of thunderstorms over the
Sierra Nevada this afternoon. Otherwise, VFR conditions will
prevail for the next 24 hours across the Central California
Interior.

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.AIR QUALITY ISSUES...
ISSUED:  05/27/2025 14:35
EXPIRES: 05/28/2025 23:59
None.



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.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.

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.HNX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory from 11 AM Friday to 7 AM PDT Sunday for
CAZ300>321-324-332.
&&

$$

public...SM/JPK
aviation....JPK

weather.gov/hanford