634
FXUS65 KPSR 101014
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
314 AM MST THU SEP 10 2026
KEY MESSAGES
- ABOVE NORMAL TEMPERATURES WILL PREVAIL THROUGH THE REST OF THE
WEEK, WITH EXTREME HEAT WARNINGS IN EFFECT FOR PORTIONS OF THE
LOWER DESERTS.
- DAILY CHANCES FOR SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WILL CONTINUE TO BE FOCUSED OVER THE EASTERN ARIZONA HIGH
TERRAIN. ANY CHANCES FOR LOWER DESERTS SHOULD BE CONFINED TO
LATE FRIDAY AND AGAIN SUNDAY INTO MONDAY.
- COOLING TEMPERATURES OVER THE WEEKEND INTO EARLY NEXT WEEK
SHOULD EVENTUALLY PUSH READINGS BACK INTO THE NORMAL RANGE BY
AROUND NEXT TUESDAY.
SHORT TERM /TODAY THROUGH FRIDAY/
STRONG HIGH PRESSURE IS CURRENTLY PLANTED OVER THE SOUTHWESTERN
U.S., BUT MOISTURE LEVELS HAVE IMPROVED ENOUGH TO BRING SOME
ISOLATED SHOWERS AND A FEW EMBEDDED STORMS OVER THE PAST SEVERAL
HOURS. THE HIGH CENTER IS CURRENTLY SITUATED OVER FAR WEST-CENTRAL
ARIZONA RESULTING IN NORTHEASTERLY MID-LEVEL FLOW, BUT WEST
SOUTHWEST LOWER LEVEL FLOW OVER MUCH OF ARIZONA. MOISTURE HAS
INCREASED ENOUGH IN THE LOWER LEVELS TO PUSH MIXING RATIOS TO
AROUND 10 G/KG OVER MUCH OF THE AREA TO UPWARDS OF 12 G/KG OVER
SOUTHEAST ARIZONA, BUT A STRONG LOWER LEVEL SUBSIDENCE INVERSION
IS ALSO IN PLACE. CONVECTION WAS QUITE EXTENSIVE DURING THE
EVENING HOURS ACROSS SOUTHEAST ARIZONA/SOUTHWEST NEW MEXICO WITH
THIS COMPLEX SENDING A LOW LEVEL OUTFLOW AND MID-LEVEL GRAVITY
WAVE EAST NORTHEASTWARD THROUGH THE REST OF ARIZONA. ISOLATED
SHOWERS HAVE POPPED OFF WITH THE PASSAGE OF THESE FEATURES,
TAPPING INTO ELEVATED INSTABILITY. WE DO NOT ANTICIPATE ANYTHING
MORE THAN VERY LIGHT RAINFALL AMOUNTS WITH ANY OF THESE SHOWERS
WITH A FOCUS MOSTLY ACROSS WESTERN MARICOPA INTO LA PAZ COUNTIES.
FOR THE REST OF TODAY, GUIDANCE IS SHOWING MUCH MORE LIMITED
CONVECTION THAN YESTERDAY, IN PARTICULAR ACROSS SOUTHEAST ARIZONA.
THE SUBSIDENCE INVERSION IS LIKELY TO TOO STRONG, KEEPING CHANCES
BELOW 10% ACROSS OUR CWA. GUIDANCE DOES SHOW SOME CONVECTION
DEVELOPING SOUTH OF THE U.S./MEXICO BORDER DURING THE EVENING, BUT
IT SEEMS QUITE UNLIKELY IT WILL SEND ANYTHING UP OUR WAY LIKE WHAT
IS CURRENTLY HAPPENING. THE PEAK STRENGTH OF THE RIDGE OCCURRED
LATE YESTERDAY AND THIS WILL TRANSLATE TO THE HOTTEST
TEMPERATURES OCCURRING TODAY. THE LOWER DESERTS OF SOUTHEAST
CALIFORNIA ARE EXPECTED TO TOP 110 DEGREES WITH HEAT INDICES UP
TO AROUND 115 DEGREES, WHILE THE ARIZONA LOWER DESERTS SHOULD SEE
HIGHS OF 107-110 DEGREES AND HEAT INDICES CLOSER TO 110 DEGREES
DURING THE AFTERNOON HOURS.
THE UPPER LEVEL RIDGE WILL CONTINUE TO WEAKEN TODAY INTO FRIDAY,
LIKELY WEAKENING ENOUGH TO LOWER TEMPERATURES A GOOD 2-4 DEGREES
ACROSS SOUTH-CENTRAL ARIZONA STARTING FRIDAY AND 1-3 DEGREES OVER
THE WESTERN DESERTS. THE EXTREME HEAT WARNINGS WILL CONTINUE
THROUGH FRIDAY FOR MUCH OF THE LOWER DESERTS OF SOUTHEAST
CALIFORNIA AND SOUTHWEST ARIZONA, WHILE EXPIRING EVERYWHERE ELSE
THIS EVENING.
FRIDAY SHOULD ALSO BRING ANOTHER INFLUX OF MOISTURE FROM THE SOUTH
SOUTHWEST, PUSHING AREA LOW LEVEL MIXING RATIOS MORE INTO A 11-12
G/KG RANGE. HOWEVER, THIS MAY STILL NOT BE ENOUGH TO SPARK OFF
MORE WIDESPREAD CONVECTION AS THE THE SUBSIDENCE INVERSION WILL
STILL BE IN PLACE (ALBEIT SLIGHTLY WEAKER) AND THE STEERING FLOW
IS EXPECTED TO TURN OUT OF THE SOUTHWEST. WE ARE EXPECTING BETTER
STORM COVERAGE ACROSS THE EASTERN ARIZONA HIGH TERRAIN ON FRIDAY,
BUT WITH A SOUTHWESTERLY STEERING FLOW IT WILL BE HARD TO GET
CONVECTION TO FIRE OVER THE LOWER DESERTS. THE NBM DOES INDICATE
25-35% POPS FRIDAY EVENING/EARLY FRIDAY NIGHT FROM PHOENIX
EASTWARD, BUT THAT SEEMS TOO OPTIMISTIC. IF STORMS DO ACTUALLY GET
GOING OVER THE SOUTH-CENTRAL ARIZONA LOWER DESERTS FRIDAY
EVENING, THEY WILL BE WITHIN A HIGH DCAPE ENVIRONMENT WHICH MEANS
STRONG WINDS WILL BE A POSSIBILITY.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
FORECAST CONFIDENCE FOR THE WEEKEND INTO NEXT WEEK REMAINS QUITE
LOW, ESPECIALLY WHEN LOOKING AT MOISTURE LEVELS AND RAIN CHANCES.
GUIDANCE DOES AGREE THE SUBTROPICAL RIDGE WILL GET PUSHED TO THE
EAST OF OUR REGION OVER THE WEEKEND AS A PACIFIC TROUGH MOVES
THROUGH THE NORTHERN TIER STATES, BUT THE GEFS IS STRONGER AND
FARTHER SOUTH WITH THE TROUGH COMPARED TO THE EPS. THE MODELS ALSO
DIFFER IN THE AMOUNT OF MOISTURE AND RAIN CHANCES DURING THE
PERIOD WITH THE GEFS FAVORING BETTER RAIN CHANCES FROM PHOENIX AND
AREAS EAST OF PHOENIX OVER THE WEEKEND, WHILE THE EPS FAVORS
BETTER CHANCES BY TUESDAY INTO THE MIDDLE OF NEXT WEEK. NEEDLESS
TO SAY, THESE DIFFERENCES DO NOT INSPIRE MUCH CONFIDENCE IN THE
AVAILABLE NBM/WPC POPS.
THE LATEST FORECAST PLACES LITTLE IF ANY POPS ON SATURDAY AND
SATURDAY NIGHT, WHICH SEEMS FAIRLY REASONABLE, BUT THEN SEEMS TO
BE UNDER DOING CHANCES LATE SUNDAY. THE INCREASED POPS OF 20-40%
THEN SEEM TOO HIGH FOR MONDAY BEFORE GRADUALLY LOWERING DURING THE
MIDDLE PART OF NEXT WEEK. LATELY, GUIDANCE HAS HAD A TENDENCY TO
PLACE FAIRLY HIGH POPS DURING THE 4-8 DAY RANGE, JUST TO BACK OFF
AS IT GETS INTO THE SHORT-TERM. IT WOULD SEEM EVERYTHING WOULD
HAVE TO COME TOGETHER NEARLY PERFECTLY WITH THE TROUGH PASSING BY
TO OUR NORTH CLOSE ENOUGH, BUT NOT TOO CLOSE TO SCOUR OUT WHAT
MOISTURE WE HAVE IN THE LOW/MID LEVELS. ADDITIONALLY, IF THE
SUBTROPICAL RIDGE BECOMES MORE DOMINANT, THEN WE WILL HAVE TO
WORRY ABOUT TOO STRONG OF A SUBSIDENCE INVERSION. GIVEN THE FAIRLY
HIGH MODEL UNCERTAINTY, THE FORECAST IS LIKELY TO CHANGE.
THE TEMPERATURE FORECAST IS ALSO OF LOWER CONFIDENCE WITH A FAIRLY
WIDE SPREAD STARTING MONDAY. AT THE MOMENT, NBM FORECAST
TEMPERATURES CALL FOR READINGS MORE IN THE NORMAL RANGE BY EARLY
NEXT WEEK, BUT GIVEN THE HIGHER MODEL SPREAD WE COULD END UP
WITH READINGS SLIGHTLY BELOW OR EVEN SLIGHTLY ABOVE NORMAL.
GUIDANCE AT LEAST MOSTLY AGREES ON THE 'COOLEST' TEMPERATURES
FALLING ON NEXT TUESDAY AND WEDNESDAY BEFORE TRENDING UPWARD
AGAIN DURING THE LATTER HALF OF NEXT WEEK.
AVIATION
UPDATED AT 1000Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
A DISTANT OUTFLOW MOVED THROUGH OVERNIGHT CARRYING SOME LOFTED DUST,
RESULTING IN TEMPORARY REDUCTIONS IN VIS BELOW 10SM. LINGERING
HAZE/LOFTED DUST MAY CAUSE SLANTWISE VISIBILITY RESTRICTIONS AROUND
SUNRISE BUT WILL IMPROVE THROUGH THE REST OF THE MORNING. OTHERWISE,
NO MAJOR AVIATION WEATHER CONCERNS ARE ANTICIPATED THROUGH THE TAF
PERIOD UNDER FEW-SCT MID AND HIGH CLOUD DECKS. WINDS WILL FOLLOW
FAIRLY TYPICAL DIURNAL TENDENCIES WITH A WESTERLY SHIFT LIKELY
BETWEEN 17-19Z. GUSTS TO AROUND 15 KTS WILL BE POSSIBLE DURING THE
AFTERNOON, RELAXING AFTER SUNSET. WEST WINDS ARE LIKELY TO INCREASE
ONCE AGAIN LATE EVENING INTO THE OVERNIGHT HOURS, DELAYING THE
TYPICAL NOCTURNAL E/SE WIND SWITCH.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION CONCERNS ARE ANTICIPATED UNDER PERIODS OF FEW-SCT
MID AND HIGH CLOUD DECKS. WINDS AT KIPL WILL FAVOR SE THROUGH THE
DAY AND VEER OUT OF THE SOUTHWEST THIS EVENING. SPEEDS WILL
GENERALLY REMAIN BELOW 10 KTS, BUT THERE MAY BE A PERIOD WITH GUSTS
TO 15-20 KTS DURING THE EVENING. THE POSSIBILITY THAT A GUSTY
OUTFLOW FROM DISTANT TS TO THE SOUTH MAY REACH THE TERMINAL MID TO
LATE AFTERNOON CANNOT BE RULED OUT, BUT IS TOO LOW PROBABILITY FOR
TAQF INCLUSION. WINDS AT KBLH WILL CONTINUE TO FAVOR S TO SW, WITH
SPEEDS GENERALLY AOB 12 KTS.
FIRE WEATHER
ABOVE NORMAL TEMPERATURES WILL CONTINUE INTO THE WEEKEND WITH
MODESTLY ELEVATED HUMIDITIES. RAIN CHANCES WILL IMPROVE BY
FRIDAY, BUT STILL MOSTLY FAVOR THE ARIZONA HIGH TERRAIN.
AFTERNOON MINIMUM HUMIDITIES OF 17-25% TODAY WILL IMPROVE TO
25-30% FOR FRIDAY AND SATURDAY. OVERNIGHT RECOVERIES WILL REMAIN
FAIR TO GOOD AT 40-70%. EXPECT FAIRLY TYPICAL DIURNAL WINDS WITH
LITTLE IF ANY BREEZINESS TODAY, BUT WITH 20-25 MPH AFTERNOON AND
EARLY EVENING GUSTS ON FRIDAY AND SATURDAY. CHANCES FOR ISOLATED
SHOWERS AND THUNDERSTORMS ARE LIKELY TO REMAIN POSSIBLE ACROSS
THE EASTERN DISTRICTS THROUGH AT LEAST EARLY NEXT WEEK WHILE
TEMPERATURES EVENTUALLY FALL BACK INTO A NORMAL RANGE.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING UNTIL 8 PM MST FRIDAY FOR AZZ530-532-533.
EXTREME HEAT WARNING UNTIL 8 PM MST THIS EVENING FOR AZZ531-
535>544-546-548>551-559.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT FRIDAY FOR CAZ562-566-567-
569-570.
SHORT TERM...KUHLMAN
LONG TERM...KUHLMAN
AVIATION...WHITTOCK
FIRE WEATHER...KUHLMAN
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