961
FXUS66 KHNX 112249
AFDHNX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HANFORD CA
349 PM PDT MON AUG 11 2025
UPDATE
AVIATION SECTION UPDATED
KEY MESSAGES
1. THIS HEAT WAVE EVENT IS EXPECTED TO REACH IT'S HOTTEST DAY
TODAY, WITH A SLIGHT 1 TO 2 DEGREE DECREASE ON TUESDAY. THIS
SLOW COOLING TREND IS EXPECTED TO CONTINUE THROUGH THIS WEEKEND.
2. THE HEAT ADVISORY REMAINS IN EFFECT FOR THE SAN JOAQUIN
VALLEY THROUGH 11 PM TONIGHT, WITH A 25 TO 55 PERCENT CHANCE FOR
HIGHS OF 105 OR HIGHER THIS AFTERNOON.
3. THE EXTREME HEAT WARNING FOR THE MOJAVE DESERT WILL REMAIN IN
EFFECT UNTIL 5 AM TOMORROW MORNING, WITH AN 80 PERCENT CHANCE
FOR HIGHS OF 110 OR HIGHER AT RIDGECREST AND A 15 TO 25 PERCENT
CHANCE IN THE REST OF THE DESERT REGION.
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
A LARGE HIGH PRESSURE RIDGE IS CURRENTLY CENTERED OFF THE WEST
COAST, WHICH IS LEADING TO INCREASED 500MB HEIGHTS OVER
CALIFORNIA. THIS HAS LEAD TO THE ABOVE NORMAL TEMPERATURES WE
HAVE BEEN SEEING FOR THE LAST FEW DAYS, AND THESE TEMPS OR
EXPECTED TO CONTINUE THROUGH TODAY AND SOMEWHAT INTO TOMORROW.
THE REASON WE MAY SEE A SLIGHT DECREASE IN HIGHS (OF A COUPLE
DEGREES), IS DUE TO THE RIDGE BEING SPLIT BY A WEAK DISTURBANCE
OVER THE OREGON COAST. THIS WILL THEN LEAD TO THE RIDGE BEING
PUSHED TO THE EAST AS A TROUGH MOVES IN FROM THE WEST. THIS WILL
LEAD TO OUR TEMPERATURES COMING DOWN TO AROUND NORMAL ONCE
AGAIN BY WEDNESDAY. THIS GRADUAL COOLING TREND IS EXPECTED TO
LAST THROUGH THE WEEKEND, WHERE HIGHS MAY BECOME BELOW NORMAL,
WHICH WOULD BE IN THE MID TO HIGH 90'S FOR THE VALLEY AND A FEW
DEGREES ABOVE THE TRIPLE DIGITS FOR THE DESERT.
RELATIVE HUMIDITY IS EXPECTED TO SEE A SIMILAR SHIFT AS WE MOVE
THROUGH THE WEEK AND BEGIN TO COOL DOWN BY THE WEEKEND. MINIMUM
RH'S TODAY ARE EXPECTED TO BE IN THE 15 TO 25 PERCENT RANGE FOR
THE VALLEY AND SINGLE DIGITS IN THE DESERT. AND DUE TO THESE LOW
RH'S AND HIGH TEMPERATURES, A MINOR FIRE RISK EXISTS FOR THE
REGION. AS WE COME UNDER THE INFLUENCE OF THE TROUGH LATER THIS
WEEK, RH'S IN THE AFTERNOON ARE EXPECTED TO SLOWLY RECOVER, WITH
VALUES IN THE VALLEY OF 25 TO 40 PERCENT, THOUGH THE DESERT MAY
REMAIN IN THE SINGLE DIGITS. THIS TROUGH IS ALSO EXPECTED TO
LEAD TO SLIGHTLY BREEZIER WINDS IN THE VALLEY AND ALONG THE
MOJAVE DESERT SLOPES, THOUGH THOSE CURRENTLY AREN'T EXPECTED TO
BE HIGH ENOUGH FOR AN ADVISORY. THESE WINDS WILL KEEP THE MINOR
FIRE RISK IN PLACE DUE TO THE DRY FINE FUELS THAT ARE STILL
ABUNDANT THROUGHOUT THE REGION.
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 UNTIL 5 AM PDT TUESDAY FOR CAZ337>339.
HEAT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR CAZ300>317-319-
321.
PUBLIC...EW
AVIATION....JPK
WEATHER.GOV/HANFORD
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