658
FXUS66 KHNX 040956
AFDHNX

Area Forecast Discussion
National Weather Service Hanford CA
256 AM PDT Thu Jul 4 2024

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.KEY MESSAGES...

1. Temperatures will climb to around 15 degrees above normal
this afternoon. This is a dangerous and prolonged heat wave
that will last several days with an Extreme Heat Risk.

2. An Excessive Heat Warning remains in effect through Thursday,
July 11th at 8 AM, and may need to be extended further as the
week progresses.

3. The risk of grass fires will continue with herbaceous fuel
loading at or near 120% of normal. A long period of excessive
heat, minimum relative humidities near 15% and poor overnight
recoveries will add to the grass fire risk.

&&

.DISCUSSION...

BLUF...Excessive heat warning to continue until further notice
(UFN).

The ridge over the eastern Pacific will relocate over the
Golden State by late this afternoon. The persistent latitudinal
shaped ridge over the southeast CONUS gets squeezed some on
Friday with a strong upper wave pushing through the Midwest.
This allows the California ridge to reoriented to a more classic
longitudinal axis as the Gulf of Alaska upper low sinks into
the North Pacific driven by a stronger upper low over Bering
Strait. This set up is a weak Rex block locking in the ridge
over California with the ridge axis right along Highway 99. The
Atlantic tropical system by Monday morning begins to come into
play with the ridge over California. The ridge retrogrades with
the axis pushing off-shore. This should tweak down temperatures
from the near records in the 110s to sub 110s but still above
105 not reducing the heat risk starting on Monday. Tuesday into
Wednesday the clusters analysis at 500 MB remains in high
confidence with the ridge axis sliding across California and
relocating over the Great Basin. The fly in the ointment is what
the tropical system ultimately does. If the energy gets into
the upper Midwest trough this supports the displacement of the
ridge to the east. It also can be noted that there is some
weakness shown in the deterministic model heading into the
middle of next week that will have to be monitored for possible
thunderstorm activity. The NBM probabilistic guidance even
hints with a tiny 3-5% possibility. The signal is too weak to
really start putting that into the forecast.

Here on the fourth of July the impacts will remain with the
excessive heat and then fire weather. Will highlight all fire
weather impacts in the break out section below. Looking at PoE
of 110 for today across the region. In the San Joaquin Valley
Visalia wins with a 60% probability of topping 110. Otherwise,
10 to 35 percent is the range for the valley. Greater than 90%
for the Kern County Desert. Looking at tonight for lows above 80
degrees we have Coalinga and Bakersfield coming in with 40 to
60 percent probability and elsewhere the probability remains
below 10 percent.

Friday through Monday features the ridge centered over the
Central Valley. PoE of 110 degrees increases with the best
probability falling on Saturday with areas south of Highway 198
having a 50 to 80 percent probability. North 35 to 55 percent on
Saturday increasing on Sunday to 45 to 70 percent.

Tuesday and Wednesday the PoE of 110 degrees ranges from 15 to
55 percent for the valley with the highest probability on the
urban areas.

&&

.AVIATION...

Continued areas of MVFR and local IFR visibility due to smoke in
and around fire complexes. Otherwise, VFR conditions will
prevail across the central California interior for the next 24
hours.

&&

.FIRE WEATHER...

The focus today is the western hills area. Afternoon relative
humidity levels fall down to 10 to 15 percent and overnight
recovery is only 25 to 35 percent. This along with late
afternoon and early evening breezes sustained around 10 to 15
mph and gusts up to 20 mph. Not to forget the holiday brings a
threat of elevated embers from exhausted festivity devices. This
poses an increased threat of fire starts.

Other area of concern is the Mojave Slopes and Kern County
Desert where the afternoon and evening northwest to southwest
winds start gusting up to 25 to 35 mph in favored windy spots
along with sub 10 percent RH values pose continued fire weather
danger for the region.

&&

.CLIMATE...

Fresno Air Terminal tied the record of 110 yesterday afternoon
at 3:40 PM that was established back in 1889, yes a 135 year old
record.

For the fourth of July here are the records...

For today Fresno`s record high is 112 degrees also set back in
1889. The PoE of breaking the record for Fresno today is 5
percent.

Bakersfield`s record is 114 degrees from the year 1931 and the
PoE of a new record is 1 percent.

Hanford`s record is 112 degrees from the year 1931 and the PoE
of a new record is 5 percent.

Madera`s record is 108 degrees from back in 1937 and the PoE of
a new record is 45 percent.

Merced`s record is 108 degrees from back in 1937 and the PoE of
a new record is 45 percent.

&&

.AIR QUALITY ISSUES...
ISSUED:  07/03/2024 14:15
EXPIRES: 07/04/2024 23:59
None.

&&

.CERTAINTY...

The level of certainty for days 1 and 2 is high.
The level of certainty for days 3 through 7 is high.

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 8 AM PDT Thursday for CAZ300>322-
324-332-334-336>339.
&&

$$

public/aviation/fire weather...Proton
IDSS....EW

weather.gov/hanford