411
FXUS65 KPSR 072306
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
405 PM MST WED OCT 7 2026
UPDATE
UPDATED AVIATION
KEY MESSAGES
- WELL ABOVE NORMAL TEMPERATURES WILL PERSIST THROUGH THE END OF THE
WEEK AS LOWER DESERT HIGHS REACH TRIPLE DIGITS.
- AN EXTREME HEAT WARNING REMAINS IN EFFECT FOR PORTIONS OF
SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA THROUGH FRIDAY AS
TEMPERATURES WARM TO NEAR RECORD LEVELS, RESULTING IN MAJOR HEATRISK.
- DRY CONDITIONS WILL PERSIST THE NEXT SEVERAL DAYS BEFORE A MORE
UNSETTLED PATTERN ARRIVES OVER THE WEEKEND WITH MUCH COOLER
TEMPERATURES AND INCREASING RAIN CHANCES.
SHORT TERM /TODAY THROUGH FRIDAY/
CURRENT REGIONAL ANALYSIS REVEALS BROAD, BUT SOMEWHAT MESSY, RIDGING
OVER MUCH OF THE WESTERN CONUS, WHILE A WEAK EMBEDDED SHORTWAVE
CONTINUES TO MEANDER AROUND THE FOUR CORNERS. THE LATTER OF THESE
FEATURES, COMBINED WITH SOME RELATIVELY DECENT MID-LEVEL MOISTURE,
MAY AID IN THE DEVELOPMENT OF SOME VERY ISOLATED AND AND
INCONSEQUENTIAL SHOWERS OVER THE WHITE MOUNTAINS THIS AFTERNOON AS
IT SLIDES DOWN INTO EASTERN ARIZONA. OUTSIDE OF THAT HOWEVER,
DOMINANT HIGH PRESSURE WILL PROMOTE DRY CONDITIONS ACROSS THE DESERT
SOUTHWEST AS WE TRANSITION TO THE BACK HALF OF THE WEEK.
THE MAIN FOCUS IN THE NEAR TERM WILL BE THE CONTINUATION OF WELL
ABOVE NORMAL TEMPERATURES. WITH HEIGHTS ALOFT TOPPING OUT BETWEEN
587-590 DAM THIS AFTERNOON, A GOOD 1-1.5 STANDARD DEVIATION ABOVE
CLIMATOLOGICAL NORMAL FOR EARLY OCTOBER, ALONG WITH 850MB
TEMPERATURES PEAKING BETWEEN 25-27C, TRIPLE DIGIT HIGHS WILL BE
QUITE COMMON THE NEXT FEW DAYS ACROSS THE LOWER DESERTS. READINGS
FOR SOUTH-CENTRAL ARIZONA WILL RANGE BETWEEN 98-103 DEGREES WHILE
SLIGHTLY HOTTER OBSERVATIONS NEAR 102-109 DEGREES CAN BE EXPECTED
ACROSS THE WESTERN DESERTS. ALTHOUGH THESE VALUES ARE NOT ATYPICAL
DURING LATE SPRING AND SUMMER, THEY WILL STILL BE 10 OR SO DEGREES
ABOVE NORMAL FOR THIS OF YEAR WHILE NEARING DAILY RECORDS AT YUMA
AND EL CENTRO. THIS WILL RESULT IN AREAS OF MAJOR HEATRISK AND THUS
EXTREME HEAT WARNINGS HAVE NOW GONE INTO EFFECT FOR THE IMPERIAL
VALLEY AND YUMA, WITH THE WARNING EXPANDED TO INCLUDE THE LOWER
COLORADO RIVER VALLEY AND ALONG I-8 IN YUMA COUNTY FOR THURSDAY.
ALTHOUGH THE RIDGE WILL BEGIN TO WANE FRIDAY, THERMAL PROFILES WILL
BE SLOW TO RESPOND WHICH WILL ALLOW FOR ONE MORE DAY OF TRIPLE DIGIT
HEAT. READINGS WILL NOT BE MUCH DIFFERENT FROM THE DAYS PRIOR, BUT
PERHAPS A DEGREE OR TWO "COOLER" FROM THURSDAY. THIS WILL ALLOW FOR
THE CESSATION OF AT LEAST PART OF THE EXTREME HEAT WARNING, BUT WITH
LINGERING MAJOR HEATRISK FOR THE IMPERIAL VALLEY AND YUMA, THESE
AREAS WILL REMAIN WITHIN SAID WARNING TO FINISH OUT THE WORKWEEK.
LONG TERM /SATURDAY THROUGH TUESDAY/
A SIGNIFICANT PATTERN SHIFT IS STILL ANTICIPATED THIS WEEKEND
THROUGH EARLY NEXT WEEK AS THE MOST OF THE DETERMINISTIC AND
ENSEMBLE MODEL GUIDANCE CONTINUES TO SHOW A BROAD TROUGHING PATTERN
SETTING UP ACROSS MUCH OF THE WESTERN THIRD OF THE CONUS. GUIDANCE
CONTINUES TO SHOW A NORTHERN STREAM TROUGH DIVING INTO THE PACIFIC
NORTHWEST ON SATURDAY BEFORE SINKING SOUTHWARD OVER CA ON SUNDAY.
MEANWHILE, A MORE SOUTHERN STREAM SHORTWAVE TROUGH IS LIKELY TO MOVE
INTO THE SUBTROPICAL EASTERN PACIFIC AND PICK UP THE REMNANTS OF
HURRICANE RACHEL AS IT MOVES NORTHEASTWARD AND PHASES WITH THE WEST
COAST TROUGH. AS THIS WHOLE PATTERN EVOLUTION TAKES SHAPE, THE
INCREASING SOUTH TO SOUTHWESTERLY FLOW ALOFT WILL ADVECT MOISTURE
INTO THE DESERT SOUTHWEST STARTING SATURDAY, WITH MOST OF THE
MOISTURE AT FIRST CONFINED IN THE MID TO UPPER-LEVELS BEFORE BETTER
LOW-LEVEL MOISTURE MOVES IN ON SUNDAY AS THE REMNANTS OF RACHEL GETS
PULLED IN.
COINCIDENTALLY, RAIN CHANCES WILL BE ON THE INCREASE AS EARLY AS
SATURDAY AFTERNOON ACROSS SOUTH-CENTRAL AZ BEFORE PEAKING SUNDAY
INTO MONDAY ACROSS MUCH OF THE REGION WITH THE ARRIVAL OF BETTER LOW-
LEVEL MOISTURE. THERE CONTINUES TO BE A GREAT DEAL OF UNCERTAINTY IN
RAINFALL AMOUNTS AS IT WILL BE DEPENDENT ON THE OVERALL TRACK OF THE
REMNANTS OF RACHEL AND HOW IT INTERACTS WITH THE WEST COAST TROUGH.
IT WILL LIKELY TAKE AT LEAST ANOTHER COUPLE OF DAYS TO GET A BETTER
IDEA ON THE RAINFALL PERSPECTIVES AS GUIDANCE COMES INTO BETTER
AGREEMENT ON HOW THE OVERALL PATTERN SHAPES UP. IN ADDITION TO THE
RAINFALL POTENTIAL, WINDS WILL BE ANOTHER HAZARD TO CONTEND WITH AS
THE COMBINATION OF THE HEIGHT FALLS FROM THE TROUGH AND REMNANT
CIRCULATION OF RACHEL WILL LIKELY RESULT IN WIDESPREAD BREEZINESS.
AS 500 MB HEIGHTS LOWER WITH THE APPROACHING TROUGH ALONG WITH
THE INCREASING CLOUD COVER AND MOISTURE, MUCH COOLER TEMPERATURES
ARE EXPECTED THIS WEEKEND INTO EARLY NEXT WEEK. AFTERNOON HIGHS
ACROSS THE LOWER DESERTS WILL GO FROM MID TO UPPER 90S ON SATURDAY
TO LOW TO MID 80S BY MONDAY AND MAY POTENTIALLY DROP EVEN LOWER
ON TUESDAY WITH MANY LOCATIONS STUCK IN THE LOW 80S.
AVIATION
UPDATED AT 2305Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
NO WEATHER ISSUES WILL EXIST THROUGH THURSDAY EVENING UNDER A FEW
AFTERNOON CUMULUS DECKS OVER MOUNTAINS. TIMING OF WIND SHIFTS WITH
SPEEDS UNDER 10KT WILL BE SIMILER TO THE PAST 24 HOURS, ALTHOUGH THE
SWITCH TO A WEST COMPONENT LATE THURSDAY AFTERNOON MAY BE MORE
SUBTLE, OR JUST RESULT IN A PROLONGED VARIABLE COMPONENT.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO WEATHER ISSUES WILL EXIST THROUGH THURSDAY EVENING UNDER CLEAR
SKIES. EXTENDED PERIODS OF LIGHT AND VARIABLE WINDS WILL CONTINUE
WITH A TENDENCY FOR DIRECTIONS TO VARY BETWEEN NORTHERLY AND
WESTERLY.
FIRE WEATHER
DRY CONDITIONS ALONG WELL-ABOVE NORMAL TEMPERATURES WILL CONTINUE
THROUGH THE END OF THE WORK WEEK AS LOWER DESERT HIGHS REACH INTO
THE TRIPLE DIGITS. WINDS THROUGH THURSDAY WILL GENERALLY BE LIGHT
AND DIURNALLY DRIVEN BEFORE INCREASING FRIDAY INTO THIS WEEKEND.
AFTERNOON MINRHS THROUGH THE END OF THE WORK WEEK WILL RANGE BETWEEN
15-25% WITH FAIR TO GOOD OVERNIGHT RECOVERIES (35-60%). A MORE
UNSETTLED WEATHER PATTERN IS EXPECTED THIS WEEKEND THROUGH EARLY
NEXT WEEK AS A WEATHER SYSTEM AFFECTS THE AREA WITH MUCH COOLER
TEMPERATURES ALONG WITH INCREASING MOISTURE AND CHANCES FOR WETTING
RAINFALL.
CLIMATE
RECORD HIGHS:
DATE YUMA EL CENTRO
---- ---- ---------
OCT 7 111 IN 2024105 IN 1991
OCT 8 107 IN 1996 106 IN 1996
OCT 9 106 IN 2024104 IN 1996
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING UNTIL 8 PM MST FRIDAY FOR AZZ532.
EXTREME HEAT WARNING FROM 10 AM TO 8 PM MST THURSDAY FOR AZZ530-
536.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT FRIDAY FOR CAZ566-567.
EXTREME HEAT WARNING FROM 10 AM TO 8 PM PDT THURSDAY FOR CAZ569-
570.
SHORT TERM...LOJERO/RW
LONG TERM...LOJERO
AVIATION...18
FIRE WEATHER...LOJERO
CLIMATE...RW
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