727
FXUS66 KHNX 111025
AFDHNX

Area Forecast Discussion
National Weather Service Hanford CA
325 AM PDT Thu Jul 11 2024

...EXTENDED HEAT ADVISORY FOR YOSEMITE UNTIL 10 AM FRIDAY...

.KEY MESSAGES...
1. A long-duration, rare heat wave with an Extreme HeatRisk
will continue through late this week will have many impacts on
all of our citizens and all sectors of the community.

2. An Excessive Heat Warning remains in effect until Saturday,
July 13 at 10 AM. A Heat Advisory remains in effect for Yosemite
NP through Thursday at 10 AM.

3. The high risk of grass fires will continue with herbaceous
fuel loading at or near 120% of normal exhibiting behavior
typically not experienced with low wind speeds.

4. Chance of afternoon thunderstorms returns to the higher
elevations of the Sierra Nevada this weekend as high level
moisture spreads over the district.

5. A Fire Weather Watch in the Sierra Nevada will be in effect
from 11 Am Saturday through 9 PM Sunday due to a 25% chance of
dry thunderstorms.

&&

.DISCUSSION...
High probability of record-breaking intense heat-wave today as
the ridge of high pressure rebounds and strengthens. After minor
change from Tuesday to Wednesday, today will see max
temperatures jump-up some 2 to 5 degrees as the Heat-Risk moves
more into the extreme category. With the marine layer at Fort
Ord currently below 2000 feet MSL, will not expect any coastal
relief from the dangerous heat. Furthermore, surface pressure
gradient from KSFO to KLAS has dropped to under 5mb as area
winds continue to diminish. The position of the ridge will now
allow monsoonal-type moisture to continue making a northwest
surge and push closer to the district. Satellite precip-water
imagery is showing higher values starting to cross the CA/AZ
state line as convection tracks closer and closer. Convection
will exist this weekend as the heat-risk begins to diminish.
Conditions expected to dry out early next week as temperatures
struggle to return to high heat-risk.

Hi-Res short-range Ensemble analysis is still showing very good
agreement with the solution of pushing a disturbance out of the
Pacific Northwest and allowing the ridge to rebuild over
California. Probability of Exceedance (PoE) of reaching 110
degrees in the 40 to 60 percent range across the San Joaquin
Valley. PoE of 105 degrees is nearly uniform near 100 percent
for the same period (today). Therefore, confidence is high that
max temperatures this afternoon will range above 110 degrees.
Overnight lows show a similar trend of having better PoE for 75
degrees than 80 degrees. Yet, a few more urban-heat-island could
see overnight lows only drop to 80 degrees. Little movement in
the ridge pattern on Friday will allow for similar dangerous
heat conditions to persist. Yet, Hi-Res Ensemble also shows a
surge of higher precip-water approaching Central California from
the Southeast (Desert Southwest) and begin affecting the area.
While limited moisture on Friday will keep convection at a
minimum, better saturation of the atmosphere on Saturday will
lead toward more widespread thunderstorms as lightning fire will
be a threat. A Fire Weather Watch is currently in effect for
Saturday as dry lightning has a 10-20 percent chance across the
Sierra Nevada.

The area of disturbance off the California Coast will finally be
picked-up by the flow aloft and sweep across the region. While
probability of precipitation does increase during the
disturbances passage, PoE of 110 degrees drops to below 20
percent. PoE of 105 degrees stays at around 20 to 50 percent
(Bakersfield show the higher percentages) with a trend toward
lower percentages on Sunday and Monday. Ensemble Cluster
Analysis agrees with the trend toward cooler temperatures with
the main threat of precipitation over the weekend. By Monday and
Tuesday, Cluster Analysis shows the disturbance sweeping east of
the district with drier air shifting into the area. At the same
time, Heat-Risk drops between Minor to patches of Moderate as
triple digit temperatures become more spotty.

&&

.AVIATION...
Areas of MVFR and local IFR visibility will continue in and
around wildfires. Otherwise, VFR conditions will prevail across
the central CA interior for the next 24 hours.

&&

.FIRE WEATHER...
Poor overnight recoveries continue through Friday, which leads
to elevated fire weather danger, considering the dry fuels even
with just diurnally driven winds. By this weekend, dry
thunderstorm activity in the Sierra Nevada is forecast, which
may lead to more fire starts. A Fire Weather Watch is in effect
in the Sierra Nevada from 11 AM Saturday through 9 PM Sunday.

&&

.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...
Excessive Heat Warning until 10 AM PDT Saturday for CAZ300>322-
324-325-332-334>339.
Fire Weather Watch from Saturday morning through Sunday
evening for CAZ592>595.
Heat Advisory until 10 AM PDT Friday for CAZ323.
&&

$$

public...Molina
aviation....EW

weather.gov/hanford