131
FXUS66 KHNX 122048
AFDHNX

Area Forecast Discussion
National Weather Service Hanford CA
148 PM PDT Wed Jun 12 2024


&&

.KEY MESSAGES...

1. A Heat Advisory remains in effect for today into Thursday
morning, with probabilities of afternoon highs exceeding 100
degrees in the San Joaquin Valley around 70-90%. The probability
of exceeding 105 degrees is generally less than 15% with the
exception of Fresno being about 25%.

2. Isolated strong thunderstorms have a 10 to 20 percent chance
of occurrence Thursday afternoon and early evening along the
Sierra Nevada crest from Yosemite NP to Sequoia NP.

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

4. Temperatures will hover between 95 and 100 degrees through
Friday before a cooling trend brings temperatures closer to
seasonal averages for the weekend. Monday temperatures will be
around 2 to 5 degrees below normal.

&&

.DISCUSSION...

Synoptic conditions over central California will continue today
as they were on Tuesday. An upper level area of high pressure
over the southwestern United States will couple with a cutoff
upper level low to bring southerly flow to the region this
afternoon through tomorrow morning. The atmospheric flow will
prolong the above average heat across the San Joaquin Valley and
Kern County Desert. A Heat Advisory remains in effect for much
of the valley portion of our CWA from Fresno County southward
due to temperatures exceeding 100 degrees this afternoon and
warm overnight conditions that will have difficulty in reducing
heat stress impacts. The following are probabilities from the
National Blend of Models to reach or exceed 100 degrees today.

Bakersfield 86%
Fresno 86%
Visalia 86%
Porterville 76%
Reedley 76%
Delano 71%
Hanford 71%
Lemoore 71%
Madera 61%
Merced 46%

An upper level trough dropping southward from the Gulf of
Alaska will be the main driver of our weather pattern for the
remainder of the week. On Thursday, the aforementioned upper
level low off the California coast will begin to move onshore,
influenced by the approach of the trough towards the Pacific
Northwest region. The cyclonic flow around the southern low
pressure system is expected to prolong winds over central
California from the south. However, these winds will be weaker
than those the past few days, resulting in slightly cooler
temperatures. NBM ensemble guidance expresses less than a 35
percent probability to exceed 99 degrees Thursday afternoon
across the San Joaquin Valley, but a 60 to 80 percent
probability to exceed 95 degrees from Fresno southward.

Temperature differences between the mountain and valley
portions of our CWA will provide enough upslope flow for the
development of thunderstorms along the crests of the Sierra
Nevada. There is currently a 10 to 20 percent chance for
stronger isolated thunderstorms reaching from Yosemite National
Park south to Sequoia National Park tomorrow afternoon and early
evening. The greatest threat associated with these forms will
be dangerous cloud to ground lightning, pea sized hail, and wind
gusts up to 40 miles per hour.

The former cutoff upper level low is projected to continue into
the central United States on Friday, bringing a pattern change
over central California. Northwesterly flow will propagate over
the region as winds flow from the aforementioned trough around
the receding low pressure system. The slight ridging pattern
this flow creates will result in afternoon highs a few degrees
warmer than Thursday. NBM ensemble guidance indicates a moderate
probability (50 to 80 percent) for maximum temperatures to
reach or exceed 97 degrees across the San Joaquin Valley on
Friday. In addition to these afternoon temperatures, the
orientation of winds aloft will bring a chance for elevated
winds along the downslope of the Tehachapi Mountains, which
includes the Kern County Desert and Mojave Desert Slopes. There
is a 60 to 90 percent chance for wind gusts greater than 55
miles per hour and a 30 to 60 percent chance for gusts greater
than 65 miles per hour Friday evening into Saturday morning.

A cooling trend is anticipated to set up over central
California beginning Saturday as westerly winds build in aloft.
This comes as the result of an area of high pressure building
over Baja California along with the aforementioned trough moving
into the Pacific Northwest. Afternoon temperatures across the
San Joaquin Valley Saturday afternoon have only a 20 to 50
percent chance to exceed 95 degrees, with less than a 25 percent
probability for Sunday and Monday. While temperatures gradually
decrease into the weekend, so will dew point temperatures, and
as a result, also relative humidity. Minimum RH values under 20
percent will be present through midweek through the San Joaquin
Valley and Kern County Desert. These lower values, coupled with
increased wind gusts, will provide prime conditions for
increased fire danger across the region.

In addition to the conditions mentioned above, rivers and
streams continue to flow dangerously fast and cold, and bodies
of water, including reservoirs, are also cold.

&&


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

&&

.AIR QUALITY ISSUES...
ISSUED:  06/11/2024 14:28
EXPIRES: 06/12/2024 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...
Heat Advisory until 6 AM PDT Thursday for CAZ304>316-319-332.
&&

$$

public/aviation...SM
DSS..............DCH

weather.gov/hanford