148
FXUS66 KHNX 082045
AFDHNX

Area Forecast Discussion
National Weather Service Hanford CA
145 PM PDT Sat Jun 8 2024

&&

.KEY MESSAGES...

1. Temperature will trend lower this weekend, but are forecast
still be around 3 to 6 degrees above normal by Sunday.

2. A few strong thunderstorms are possible this afternoon for
the crests of the Sierra Nevada mainly over Fresno and Tulare
counties.

3. An Excessive Heat Watch has been issued for Tuesday and
Wednesday with probabilities of afternoon highs exceeding 100
degrees in the San Joaquin Valley between 70 and 95 percent.
Probability of exceeding 105 degrees on Wednesday is 26 to 51
percent.

4. The warm temperatures will allow increased snowmelt to
continue over the Sierra Nevada, resulting in colder and higher
flows along rivers and waterways.

&&

.DISCUSSION...

Ridging over the Great Basin with a trough moving through the
Pacific Northwest starts off the weather picture this afternoon.
The falling heights will allow for some possible thunderstorms
to develop over the crests of the Sierra Nevada for Fresno and
Tulare counties. The probability of thunder is 15 to 20 percent
for the crests and falls to less than 5 percent for the
foothills. The probability of exceeding (PoE) 95 degrees this
afternoon is lowest for Merced and Madera with a range of 11 to
26 percent, whereas Fresno south as a range of 61 to 76 percent.
Over in the Kern County Desert China Lake has a PoE of 100
degrees of 96 percent and Edwards AFB comes in much lower at 6
percent.

On Sunday the trough begins to form a cut-off low southwest of
Catalina Island. The upper level heights fall a bit lower than
Saturday again allowing for some afternoon thunderstorm activity
over the Sierra Nevada crests main for Fresno and Tulare
counties. The probability of thunder continues in the 15 to 20
percent range for the Sierra crests and lowering to less than 5
percent for the foothills. Turning over to temperatures Sunday
afternoon the PoE of 95 degrees lower to less than 10 percent
for Merced, Madera, and Reedley. Where Fresno heading south in
the San Joaquin Valley the range is 26 to 36 percent. In the
Kern County Desert the range is 51 to 96 percent.

Monday features the Catalina cut-off holding in place between a
Central Pacific Ridge building in from the west and the ridge
over Mexico nudging in from the southeast. The building upper
heights is expected to suppress any thunderstorm activity over
the Sierra crest as probabilities fall to less than 5 percent.
Temperatures are expected to creep up a couple of degrees with
the PoE of 95 degrees 41 to 61 percent for the SJV and 76 to
near 100 percent for the Kern County Desert. The PoE of 100
degrees is less than 11 percent for the SJV and 21 to 61 percent
in the Kern County Desert.

On Tuesday the Catalina cut-off holds its ground as the Central
Pacific Ridge joins forces over the Central Mexico Ridge over
Central California. This will bump temperatures up across the
region into the concern area for Excessive Heat highlights. The
PoE of 100 degrees moves to 66 to 76 percent for the SJV and 86
to 100 percent for the Kern County Desert. The PoE of 105
degrees is less than 10 percent for Merced, Madera, Reedley, and
Delano whereas Fresno, Hanford, Visalia, and Bakersfield range
from 11 to 16 percent. The main issue on Tuesday is the lack of
cooling overnight. The PoE of low temperatures staying above 70
degrees at Fresno is 91 percent and Bakersfield 81 percent the
rest of the region is below 20 percent. Even going up to 75
degrees on PoE Bakersfield is at 26 percent and Fresno 16
percent. The excessive heat risk is moderate to extreme along
the Highway 99 corridor with the highest impact expected in
urban areas. The probabilities warrant an Excessive Heat Watch
and will introduce the highlight this afternoon for the SJV.

Wednesday the battle continues with the twin ridges and the
upper low. The little movement in the systems will allow for a
few more degrees of warming for the region. The lack of support
will keep thunderstorm probabilities for the Sierra crests below
5 percent. The Excessive Heat is expected to continue for the
region on Wednesday. The PoE of 105 degrees across the SJV
ranges from 26 to 51 percent with Fresno at 51 percent. The PoE
of staying above 70 degrees continues Wednesday night with
Fresno at 66 percent, Bakersfield at 51 percent, Reedley 21
percent, Hanford 11 percent, and the remainder of the SJV below
10 percent. The Excessive Heat Watch will cover this time frame
for the SJV. There is some concern for China Lake area with PoE
of 110 coming up to 26 percent. Will have to monitor further to
possibly add the Kern County Desert to the Excessive Heat
impact highlights.

Thursday an upper low over the Gulf of Alaska begins to push
southeast this will give an extra push the cut-off low and bring
it across Southern California and ending the dominance of the
impacts of upper level ridging for Central California. The PoE
of 100 degrees for the SJV retreats to 16 to 36 percent. The
threat of excessive heat will abate on Thursday for the area.
The upper low is far enough south that the threat of Sierra
thunderstorms remains below a probability of 5 percent.

Friday into next Saturday the upper low turns into a wave and
ejects to the four-corners region and beyond. The Ridge over the
the central Pacific and over Mexico reconnect to the west of the
Golden State as the Gulf of Alaska upper low now relocates to
near Vancouver Island and is the dominate driver of the upper
flow. Temperatures over Central California fall back some
however remain slightly above normal, with normals right around
90 degrees. The PoE of 90 degrees is between 71 to 81 percent.
Sierra Nevada Crest thunderstorm probability remains below 5
percent.

&&

.AVIATION...
VFR conditions will prevail across the Central CA
interior for the next 24 hours.

&&

.AIR QUALITY ISSUES...
ISSUED:  06/07/2024 14:59
EXPIRES: 06/08/2024 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 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 Watch from Tuesday morning through late
Wednesday night for CAZ301>303-305>317-319-332.
&&

$$

Operations...Proton
DSS....JPK

weather.gov/hanford