030
FXUS65 KPSR 061028
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
328 AM MST TUE OCT 6 2026
KEY MESSAGES
- ABOVE NORMAL TEMPERATURES WITH MINIMAL DAY TO DAY CHANGES WILL
CARRY THROUGH THE REST OF THIS WEEK AS LOWER DESERT HIGHS TOP
OUT AROUND 98 TO 107 DEGREES.
- AN EXTREME HEAT WATCH IS IN EFFECT FOR PORTIONS OF SOUTHEAST
CALIFORNIA AND SOUTHWEST ARIZONA FROM WEDNESDAY THROUGH FRIDAY
AS TEMPERATURES WARM TO NEAR RECORD LEVELS, RESULTING IN MAJOR
HEATRISK.
- DRY WEATHER WITH ZERO RAIN CHANCES WILL PERSIST THROUGH SATURDAY
BEFORE A POTENTIAL COOLER AND MORE UNSETTLED WEATHER PATTERN
ARRIVES SUNDAY INTO EARLY NEXT WEEK.
SHORT TERM /TODAY THROUGH WEDNESDAY/
LATEST GOES MID-LVL WV IMAGERY AND 500 MB OBJECTIVE ANALYSIS
REVEALS A BROAD AREA OF HIGH PRESSURE ENCOMPASSING MUCH OF THE
DESERT SOUTHWEST WHILE A WEAK SHORTWAVE TROUGH IS PROGRESSING
THROUGH THE INTERMOUNTAIN WEST. LOOKING FARTHER SOUTHWEST,
HURRICANE RACHEL IN THE E PACIFIC IS CHURNING WELL WEST OF THE TIP
OF THE BAJA CALIFORNIA AND CONTINUES TO SLOWLY PROGRESS WWD INTO
OPEN WATERS. MOISTURE FROM RACHEL WILL LIKELY COME INTO PLAY
LATER THIS UPCOMING WEEKEND, PROVIDING THE NEXT DECENT CHANCE FOR
RAIN ACROSS AZ AND SOUTHEAST CA. UNTIL THEN, DRY CONDITIONS ARE
EXPECTED THROUGH THE REMAINDER OF THIS WEEK.
WE WILL CONTINUE A WARMING TREND TODAY AND TOMORROW AS HIGH
PRESSURE BUILDS OVER SOCAL WITH POSITIVE HGHT ANOMALIES EXPANDING
OVER THE ENTIRE FORECAST AREA. THE AFOREMENTIONED WEAK SHORTWAVE
TROUGH WILL SLIDE THROUGH THE FOUR CORNERS AREA OVER THE NEXT
COUPLE DAYS, BRINGING ISOLATED SHOWERS TO THE HIGH TERRAIN OF E
AZ, BUT SOUTH-CENTRAL AZ WILL REMAIN DRY. THE MOST PRONOUNCED
POSITIVE 500 MB HGHT ANOMALIES TODAY WILL AGAIN BE FOCUSED ALONG
AND WEST OF THE LOWER COLORADO RIVER VALLEY WHERE HIGHS ARE
EXPECTED TO TOP OUT AROUND 99-104 DEGREES, WHICH IS A SOLID 8-10
DEGREES ABOVE NORMAL FOR EARLY OCTOBER. HIGHS IN THE CENTRAL AZ
DESERTS WILL NOT BE AS HOT AS AREAS FARTHER WEST, BUT ARE STILL
EXPECTED TO REACH THE UPPER 90S TO AROUND 100 DEGREES IN MANY
LOCATIONS THIS AFTERNOON. AS MID-LVL HGHTS/THICKNESS INCREASE
FURTHER ON WEDNESDAY, SFC TEMPERATURES WILL WARM 2-4 DEGREES
ACROSS THE BOARD, WITH NEARLY ALL LOWER DESERT COMMUNITIES
REACHING 100+ DEGREES IN THE AFTERNOON. THE HOTTEST LOCATIONS
WILL AGAIN BE ALONG THE GILA AND COLORADO RIVER VALLEYS AS WELL
AS IMPERIAL VALLEY WHERE HIGHS ON WEDNESDAY AFTERNOON WILL REACH
THE 102-105 DEGREE RANGE, WHICH IS UPWARDS OF 10-12 DEGREES ABOVE
NORMAL OR NEAR DAILY RECORDS. AN EXTREME HEAT WATCH REMAINS IN
EFFECT BEGINNING ON WEDNESDAY FOR THE IMPERIAL VALLEY AND YUMA.
LONG TERM /THURSDAY THROUGH MONDAY/
RIDGING ALOFT WILL REACH PEAK STRENGTH OVER THE WESTERN HALF OF
THE FORECAST AREA ON THURSDAY WITH LOW-LVL THERMAL PROFILES
RESPONDING AS 850 MB TEMPERATURES CLIMB TO AROUND 26-27C. THIS
WILL RESULT IN SFC HIGHS REACHING 102-107 DEGREES ACROSS THE
WESTERN DESERTS, AGAIN NEARING DAILY RECORDS IN YUMA AND THE
IMPERIAL VALLEY. MAJOR HEATRISK IS EXPECTED TO BE MOST EXPANSIVE
ON THURSDAY AFTERNOON AND THEREFORE THE EXTREME HEAT WATCH HAS
BEEN EXPANDED TO INCLUDE THE ENTIRE LOWER COLORADO RIVER VALLEY
AND A PORTION OF THE GILA RIVER VALLEY IN YUMA COUNTY INCLUDING
DATELAND AND TACNA. PORTIONS OF SOUTH-CENTRAL AZ WILL ALSO SEE
HIGHS CLIMB INTO THE LOW 100S OR AROUND 10 DEGREES ABOVE NORMAL ON
THURSDAY, ALTHOUGH THE HEATRISK IS EXPECTED TO REMAIN IN THE
MODERATE CATEGORY. FRIDAY WILL BE A TRANSITION DAY WHERE A
DEEPENING TROUGH OVER THE PAC NW WHICH IN TURN INDUCES SW FLOW
ALOFT OVER THE WEST COAST. ALTHOUGH WE WILL BEGIN TO SEE A
REDUCTION IN OVERALL HGHTS ALOFT ON FRIDAY AFTERNOON, LOW-LVL
THERMAL PROFILES WILL BE SLOW TO RESPOND AS 850 MB TEMPERATURES
ARE STILL EXPECTED TO REACH 25-26C ACROSS THE MUCH OF THE FORECAST
AREA EQUATING TO SFC HIGHS AROUND 100-105 DEGREES IN MOST LOWER
DESERT COMMUNITIES. SINCE THE LATEST NBM FORECAST SHOWS A 50-70%
PROBABILITY OF HIGH TEMPERATURES REACHING THE MAJOR HEATRISK
CATEGORY FOR THE IMPERIAL VALLEY AND YUMA AREA, THE DECISION WAS
MADE TO EXTEND THE EXTREME HEAT WATCH FOR THOSE AREAS THROUGH
FRIDAY EVENING.
WE THEN TURN OUR ATTENTION TO AN UPCOMING PATTERN SHIFT HEADING
INTO THIS WEEKEND AS MOST DETERMINISTIC MODELS AND ENSEMBLE
MEMBERS ARE TRENDING TOWARD AN OVERALL TROFFING PATTERN SETTING UP
ACROSS THE WESTERN CONUS. THERE IS NOW BETTER MODEL AGREEMENT
THAT A STRONGER AND DEEPER TROUGH WILL TRANSITION INTO A CUTOFF
LOW OVER THE PAC NW ON SATURDAY AND GRADUALLY SINK SOUTHWARD INTO
CA SUNDAY AND MONDAY. MEANWHILE, LATEST FORECAST GUIDANCE FROM THE
NHC SHOWS AN EVENTUAL TURN TO THE NORTHEAST BY RACHEL THIS
WEEKEND WITH THE REMNANTS OF THE STORM ITSELF BEING PULLED
NORTHEASTWARD AND PHASING WITH THE WEST COAST TROUGH. AS THIS
PATTERN TRANSPIRES, THERE SHOULD BE AN INCREASE IN SOUTHWESTERLY
FLOW ALOFT OVER THE DESERT SOUTHWEST WHICH WILL BEGIN TO PULL
PACIFIC MOISTURE INTO THE REGION BY LATE SATURDAY INTO SUNDAY.
COINCIDENTALLY, RAIN CHANCES WILL RETURN TO THE MUCH OF THE REGION
WITH NBM POPS NOW AROUND 20-50% ACROSS SOUTH-CENTRAL AZ ON SUNDAY
AND EVEN UP TO 40-60% ACROSS THE FOOTHILLS NE OF PHOENIX BY
MONDAY. THERE IS STILL HIGH UNCERTAINTY IN RAINFALL AMOUNTS AT
THIS TIME BUT THERE IS AT LEAST A CHANCE OF SOME HIGHER TOTALS
EXCEEDING 1.50" ACROSS AZ HIGH TERRAIN. AS 500 MB HGHTS BEGIN TO
LOWER AHEAD OF THE APPROACHING TROUGH ALONG WITH INCREASING CLOUD
COVER AND MOISTURE, HIGH TEMPERATURES WILL TAKE A DIVE FROM THE
MID 90S ON SATURDAY TO THE LOW TO MID 80S BY MONDAY.
AVIATION
UPDATED AT 0515Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
NO WEATHER CONCERNS WILL EXIST THROUGH TUESDAY NIGHT UNDER
OCCASIONAL MIDLEVEL CLOUD DECKS. CONFIDENCE IS EXCELLENT THAT
EASTERLY WINDS WILL PERSIST WELL INTO TUESDAY AFTERNOON BEFORE
EVENTUALLY SWITCHING TO THE TRADITIONAL WESTERLY DIRECTION LATE
AFTERNOON/EARLY EVENING.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO WEATHER ISSUES WILL EXIST THROUGH TUESDAY NIGHT UNDER CLEAR
SKIES. WINDS WILL GENERALLY MAINTAIN SOME VERSION OF A NORTHERLY
COMPONENT, HOWEVER EXTENDED PERIODS OF LIGHT AND VARIABLE WINDS WILL
BE COMMON.
FIRE WEATHER
DRY CONDITIONS WITH WELL ABOVE NORMAL TEMPERATURES WILL CONTINUE
THROUGH THE WEEK, WITH AFTERNOON HIGHS REACHING UP TO 100-107
DEGREES ACROSS THE LOWER DESERTS (PEAKING THURSDAY). WINDS WILL
RETURN TO THEIR MORE TYPICAL LIGHT DIURNAL TENDENCIES TODAY AND
PERSIST INTO THURSDAY BEFORE INCREASING AGAIN FRIDAY INTO THIS
WEEKEND. MINRHS WILL MOSTLY RANGE FROM 15-25% ACROSS THE WESTERN
DISTRICTS TO 20-35% ACROSS EASTERN DISTRICTS THROUGH THE WEEK WITH
FAIR TO GOOD OVERNIGHT RECOVERY (35-60%) AREA-WIDE. HUMIDITIES
WILL BE LOWEST ON THURSDAY WHEN TEMPERATURES ARE LIKELY AT THEIR
HOTTEST, BUT WINDS WILL STILL BE LIGHT AT THIS TIME, SO THERE ARE
NO ELEVATED FIRE WEATHER CONCERNS. NO WETTING RAIN EXPECTED
THROUGH AT LEAST SATURDAY. HOWEVER, CHANCES FOR WETTING RAINFALL
IS EXPECTED TO ARRIVE BY THE END OF THE WEEKEND/START OF NEXT
WEEK AS A WEATHER SYSTEM BEGINS TO MOVE INTO THE REGION.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WATCH FROM WEDNESDAY MORNING THROUGH FRIDAY EVENING
FOR AZZ532.
EXTREME HEAT WATCH FROM THURSDAY MORNING THROUGH THURSDAY
EVENING FOR AZZ530-536.
CA...EXTREME HEAT WATCH FROM WEDNESDAY MORNING THROUGH FRIDAY EVENING
FOR CAZ566-567.
EXTREME HEAT WATCH FROM THURSDAY MORNING THROUGH THURSDAY
EVENING FOR CAZ569-570.
SHORT TERM...SALERNO
LONG TERM...SALERNO
AVIATION...18
FIRE WEATHER...BENEDICT/SALERNO
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