971
FXUS66 KHNX 080604
AFDHNX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HANFORD CA
1104 PM PDT MON SEP 7 2026
KEY MESSAGES
1. HEAT ADVISORY ISSUED FOR THE SAN JOAQUIN VALLEY, SIERRA
FOOTHILLS AND WEST SIDE HILLS ALONG THE COASTAL RANGE.
2. MEDIUM TO HIGH PROBABILITY (70 TO 80 PERCENT) FOR TRIPLE-
DIGIT HIGHS IN THE SAN JOAQUIN VALLEY THURSDAY.
3. DECREASING CONFIDENCE IN PRECIPITATION WEDNESDAY. MEDIUM
PROBABILITY (40 TO 50 PERCENT) FOR MEASURABLE RAINFALL IN THE
SIERRA NEVADA.
DISCUSSION
THE WARMING TREND THAT BEGAN TODAY WILL CONTINUE THROUGH THIS
WEEK AS A RIDGE SLOWING BUILDS IN FROM THE EAST AS A LOW
PRESSURE CUT-OFF IS FORMING OFF THE COAST OF CALIFORNIA. THIS
TREND IS EXPECTED TO PEAK ON THURSDAY WITH THE VALLEY REACHING
HIGHS OF 101 TO 103 DEGREES AND THE DESERT SEEING HIGHS OF 103
TO 106 DEGREES. THE NIGHTTIME LOWS FROM WEDNESDAY INTO THURSDAY
WILL ALSO BE ELEVATED AS VALLEY TEMPERATURES WILL ONLY COOL INTO
THE MID TO UPPER 60'S IN THE RURAL AREAS AND IN THE LOW TO MID
70'S IN THE URBAN AREAS, LEADING TO INADEQUATE COOLING FOR THOSE
WITHOUT AIR CONDITIONING. THIS MODERATE TO MAJOR HEAT RISK
AFFECTS MUCH OF THE POPULATION. THE DESERT IS ALSO LIKELY TO
SEE LOWS IN THE MID TO UPPER 70'S. A HEAT ADVISORY HAS BEEN
ISSUED FOR THE VALLEY, WEST SIDE HILLS AND SIERRA NEVADA
FOOTHILLS DUE TO THESE CONDITIONS FROM 10 AM WEDNESDAY THROUGH
10 PM THURSDAY.
AT THE SAME TIME, MOISTURE FROM THE CURRENT TROPICAL SYSTEM
MARIE (THOUGH BY THIS TIME IN THE FORECAST, HAS BECOME A CUT-OFF
AREA OF LOW PRESSURE) MAY ENTER OUR AREA ON WEDNESDAY INTO
THURSDAY, CAUSING A SMALL AMOUNT OF RAIN TO FALL OVER THE
HIGHEST ELEVATIONS OF THE SIERRA NEVADA. CURRENT CHANCES FOR
MEASUREABLE PRECIPITATION IS 40-50%, THOUGH THESE CHANCES HAVE
BEEN DECREASING IN THE LAST FEW MODEL RUNS, SUGGESTING RAINFALL
WILL BE MINIMAL, IF IT OCCURS AT ALL.
LOOKING TO THE END OF THIS WEEK INTO EARLY NEXT WEEK,
TEMPERATURES ARE EXPECTED TO COOL DOWN STARTING ON FRIDAY AND
CONTINUE THROUGH SUNDAY AS A TROUGH MOVING DOWN FROM BRITISH
COLOMBIA PUSHING THE RIDGE BACK EAST AS IT MOVES THROUGH
NORTHERN CALIFORNIA. AFTER THIS TROUGH LEAVES THE WEST COAST,
MORE ZONAL FLOW WILL TAKE OVER, CAUSING A SMALL RISE IN
TEMPERATURES BEFORE BECOMING STABLE AROUND NORMAL VALUES SEEN
FOR THIS TIME FOR YEAR (IN THE LOW 90'S FOR THE VALLEY). THE
LONG TERM FORECAST CURRENTLY SHOWS THE REGION LEANING ABOVE
NORMAL FOR TEMPERATURES IN THE 6 TO 10 DAY AND 8 TO 14 DAY
PERIODS AS A POTENTIAL WEAK RIDGE MOVES BACK IN FROM THE EAST,
THOUGH TRIPLE DIGITS BECOME LESS LIKELY AS WE MOVE FURTHER
THROUGH SEPTEMBER.
AVIATION
VFR CONDITIONS EXPECTED 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
HEAT ADVISORY FROM 10 AM WEDNESDAY TO 10 PM PDT THURSDAY FOR
CAZ300>317-319-321.
EW
WEATHER.GOV/HANFORD
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