249
FXUS66 KHNX 101800
AFDHNX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HANFORD CA
1100 AM PDT SUN AUG 10 2025
KEY MESSAGES
1. HEAT-WAVE STARTED THIS WEEKEND AS TRIPLE DIGIT HEAT EXPECTED
THROUGH AT LEAST TUESDAY.
2. EXTREME HEAT WARNING FOR THE KERN DESERT TODAY AND MONDAY
WITH A 40 TO 60 PERCENT CHANCE OF DESERT TEMPERATURES REACHING
110 DEGREES BOTH DAYS.
3. HEAT ADVISORY FOR THE SAN JOAQUIN VALLEY TODAY AND MONDAY
WITH A 50 TO 70 PERCENT CHANCE OF VALLEY TEMPERATURES REACHING
105 DEGREES BOTH DAYS.
4. MINOR FIRE RISK WITH WIDESPREAD MINIMUM RELATIVE HUMIDITY
BETWEEN 15 AND 25 PERCENT FOR THE NON-DESERT AREAS. MINIMUM
RELATIVE HUMIDITY EXPECTED TO BE LESS THAN 10 PERCENT IN THE
MOJAVE DESERT WITH BREEZY WINDS IN THE AFTERNOON TO EVENING.
DISCUSSION
HEAT-WAVE UNDERWAY AS TRIPLE DIGIT HEAT TAKES OVER THE CENTRAL
CALIFORNIA INTERIOR. ENSEMBLE HIGH-RES SHORT-RANGE UPPER-AIR
ANALYSIS HAS SEEN FURTHER AMPLIFICATION OF THE ASSOCIATED HIGH
PRESSURE RIDGE OVER THE WEST. WHILE PROBABILITY OF EXCEEDANCE
(POE) OF REACHING 100 DEGREES IS VERY HIGH THROUGH-OUT CENTRAL
CALIFORNIA, IT IS NOW TIME TO CONSIDER THE POE OF 105 AND 110
DEGREES. EVEN AS 24 HOUR CHANGE IN TEMPERATURE BACKING OFF ON
RUNNING WARMER, POE NOW HAS A MUCH WIDER COVERAGE OF POE AT OR
ABOVE 50%. THIS HOLDS TRUE FOR THIS AFTERNOON AND MONDAY. ACROSS
THE KERN DESERT, THE 10TH TO 90TH PERCENTILES SHOWS A RANGE OF
POSSIBLE VALUES BETWEEN 105 AND 111 DEGREES, RESPECTIVELY. WITH
A MEAN MAX TEMPERATURE ABOVE THE 10TH PERCENTILE, A VERY HOT DAY
IS IN STORE FOR THE KERN DESERT TODAY AND MONDAY. WILL OPT FOR
AN EXTREME HEAT WARNING FOR TODAY AND MONDAY AS EXPECTED HIGHS
WILL REACH CRITICAL HEAT CRITERIA. LITTLE CHANGE IS EXPECTED
THROUGH TUESDAY AHEAD OF A DISTURBANCE THAT WILL BEGIN A COOLING
TREND BY MIDWEEK.
UNTIL THE RIDGE PATTERN BREAKS DOWN DUE TO A PASSING PACIFIC
NORTHWEST DISTURBANCE, THE REGION WILL BE DOMINATED BY THE HEAT.
THE ONSET OF SIGNIFICANT TEMPERATURE CHANGES IS EXPECTED
BETWEEN WEDNESDAY AND THURSDAY AS TEMPERATURES TREND TOWARD
SEASONAL NORMAL VALUES. BY THURSDAY THE CHANCES OF REACHING 100
DEGREES TAPERS OFF AS POCKETS OF POE ABOVE 50% WILL EXIST ACROSS
THE AREA. ON FRIDAY, POE OF 50% BECOME NON-EXISTENT AS MAX
TEMPERATURES ARE EXPECTED TO DROP BELOW TRIPLE DIGIT VALUES. THE
INITIAL ARRIVAL OF THE PACIFIC DISTURBANCE WILL INTRODUCE
MARINE MOISTURE INTO THE REGION AND SPARK AFTERNOON CONVECTION
ACROSS THE SIERRA NEVADA CREST ON TUESDAY. MOISTURE WILL BE
LIMITED WITH BRIEF SHOWERS OVER THE HIGH MOUNTAIN TERRAIN.
ADDITIONAL DISTURBANCE MOVING THROUGH THE ARE LATER NEXT WEEK
WILL MAINTAIN A GOOD WESTERLY FLOW AND PREVENT A REBOUND OF THE
HEAT-WAVE THROUGH AT LEAST NEXT WEEKEND.
AVIATION
18Z UPDATE:
VFR CONDITIONS ARE EXPECTED IN THE SAN JOAQUIN VALLEY FOR THE NEXT
24 HOURS.
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
EXTREME HEAT WARNING FROM 2 PM THIS AFTERNOON TO 5 AM PDT
TUESDAY FOR CAZ337>339.
HEAT ADVISORY UNTIL 11 PM PDT MONDAY FOR CAZ300>317-319-321.
PUBLIC...MOLINA
AVIATION....JPK
WEATHER.GOV/HANFORD
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