154
FXUS65 KPSR 120007
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
507 PM MST FRI SEP 11 2026
UPDATE
UPDATED 00Z AVIATION DISCUSSION.
KEY MESSAGES
- EXTREME HEAT WARNINGS CONTINUE ACROSS PORTIONS OF SOUTHEAST
CALIFORNIA AND SOUTHWEST ARIZONA THROUGH THIS EVENING AHEAD OF
SLIGHTLY COOLING TEMPERATURES THROUGH THE WEEKEND.
- SHOWER AND THUNDERSTORM CHANCES WILL BE FOCUSED MAINLY OVER THE
HIGH TERRAIN OF NORTHERN AND EASTERN ARIZONA OVER THE NEXT FEW
DAYS BEFORE INCREASING COVERAGE AND SPREADING INTO THE LOWER
DESERTS EARLY NEXT WEEK.
- NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES ARE EXPECTED FOR
THIS WEEKEND AND LIKELY THROUGH THE FIRST PART OF NEXT WEEK.
SHORT TERM /TODAY THROUGH SATURDAY/
CURRENT UPPER-AIR ANALYSIS REVEALS FLAT RIDGING OVER THE THE DESERT
SOUTHWEST AS TROUGHING OVER THE PACIFIC NORTHWEST DISPLACES THE SUB-
TROPICAL HIGH TOWARD SOUTHERN ARIZONA AND NORTHERN MEXICO. THESE
CLASHING AIR MASSES HAVE ALSO TRANSLATED TO A BIT OF HIGH
PRESSURE EROSION WHICH WILL RESULT IN SOME SLIGHTLY "COOLER"
TEMPERATURES ACROSS ACROSS THE REGION. HOWEVER, THE DIFFERENCE
COMPARED TO THE PREVIOUS FEW DAYS WILL NOT BE INCREDIBLY
NOTICEABLE, IN FACT, EXTREME HEAT CONDITIONS WILL CONTINUE THROUGH
AT LEAST THIS EVENING FOR PORTIONS OF SOUTHEAST CALIFORNIA AND
SOUTHWEST ARIZONA. AFTERNOON HIGHS TODAY OVER THESE AREAS WILL
RANGE BETWEEN 105-111 DEGREES, BUT IT WILL FEEL EVEN HOTTER THANKS
TO ABUNDANT SURFACE MOISTURE. APPARENT TEMPERATURES WILL RANGE
CLOSER TO 110-115 DEGREES AS DEW POINTS HOVER IN THE LOWER TO
UPPER 60S. ELSEWHERE ACROSS THE LOWER DESERTS, AFTERNOON READINGS
WILL RUN NEAR 100-106 DEGREES, BACKING AWAY FROM MAJOR HEATRISK,
BUT STILL AROUND 5 DEGREES ABOVE NORMAL FOR THIS TIME OF YEAR.
ALTHOUGH THE EXPECTATION IS THAT SHOWER AND THUNDERSTORM ACTIVITY
WILL BE FOCUSED OVER THE HIGH TERRAIN AREAS OF NORTHERN AND EASTERN
ARIZONA OVER THE NEXT FEW DAYS, IT IS NOT OUT OF THE REALM OF
POSSIBILITY THAT SOME ACTIVITY COULD SNEAK OVER PARTS OF THE LOWER
DESERTS THIS EVENING/TONIGHT. THE TWO MAIN FACTORS THAT WILL
DETERMINE IF THIS COMES TO FRUITION ARE IF A STRONG ENOUGH OUTFLOW
OR COLLIDING OUTFLOWS FROM DISTANT CONVECTION WILL OCCUR AND THE
TIMING OF THIS POTENTIAL OUTCOME. THE ENVIRONMENT WILL BE
FAVORABLE FOR CONVECTION THIS AFTERNOON WITH FORECAST SOUNDINGS
INDICATING MIXING RATIOS OF 14 G/KG AND ML CAPE VALUES POSSIBLY
NEAR OR EXCEEDING 1500 J/KG. HOWEVER, HI-RES GUIDANCE IS
INDICATING THAT IF OUTFLOWS, PROVIDING THE NEEDED LIFT, WERE TO
APPROACH POPULATION CENTERS OF PINAL AND MARICOPA COUNTIES, IT
WOULD NOT BE UNTIL AFTER SUNSET, AT A TIME WHEN INSTABILITY WOULD
BE ON THE DECREASE WHILE THE CAP REBUILDS. NOT TO MENTION THAT
ANYTHING THAT MAY FIRE UP WILL ALSO HAVE TO DEAL WITH SYNOPTIC
SUBSIDENCE DUE TO THE SUB-TROPICAL HIGH. THE BOTTOM LINE IS,
LOWER ELEVATION CONVECTION WILL BE HEAVILY CONDITIONAL ON HOW
ACTIVITY EVOLVES ELSEWHERE, AND THEREFORE, RAIN CHANCES ARE ONLY
20-25% FOR AREAS SUCH AS THE PHOENIX METRO TONIGHT AS A LOT OF
UNCERTAINTY REMAINS IN THE FORECAST. FURTHER EAST OVER THE
FOOTHILL AND MOUNTAINOUS AREAS, IT IS NOT SURPRISE THAT SLIGHTLY
BETTER CHANCES (30-40%) FOR RAIN EXIST THANKS TO OROGRAPHIC
INFLUENCES.
AS FOR SATURDAY, IT APPEARS THAT RAIN CHANCES OF BACKED OFF COMPARED
TO PREVIOUS FORECAST RUNS. TOMORROW MIGHT BE MORE OF DOWN DAY IN
TERMS OF CONVECTION ACROSS MOST OF THE STATE, RELATIVE TO WHAT IS
EXPECTED THIS AFTERNOON. WITH THE HIGH AND ASSOCIATED SUBSIDENCE
STILL OVERHEAD, AND THE ATMOSPHERE LIKELY TO BE WORKED OVER,
THUNDERSTORM COVERAGE WOULD LIKELY BE MORE ISOLATED TO A FEW SPOTS
OVER THE RIM AND ENHANCED TERRAIN FEATURES OF SOUTHEAST ARIZONA.
EVEN WITH A DECENT ENVIRONMENT STILL IN PLACE WITH PROJECTED ML
CAPE ~1200 J/KG AND MIXING RATIONS ~13 G/KG, WITHOUT A LARGER
COMPLEX OF CONVECTION SENDING ORGANIZED OUTFLOWS OUR WAY, THERE
WILL BE AN ABSENCE OF LIFT TO SPARK MORE SHOWERS AND STORMS
DOWNSTREAM OVER THE LOWER DESERTS OF OUR FORECAST AREA. SO FAR,
THE EARLY HI-RES RUNS FAVOR THIS DRIER OUTCOME. REGARDLESS OF HOW
CONVECTION TRANSPIRES, DAY-TO-DAY TEMPERATURES WILL FALL SLIGHTLY,
WITH AFTERNOON HIGHS RANGING BETWEEN 99-108 DEGREES. HEATRISK
LEVELS WILL BE IN THE MINOR TO MODERATE CATEGORY FOR MOST OF THE
REGION, WARRANTING THE CONCLUSION OF THIS STRETCH OF EXTREME HEAT
PRODUCTS, BUT A FEW ISOLATED SPOTS OF MAJOR HEAT RISK WILL LINGER,
MAINLY FOR THE IMPERIAL AND LOWER COLORADO RIVER VALLEYS.
LONG TERM /SUNDAY THROUGH THURSDAY/
AS STATED LAST NIGHT, FORECAST UNCERTAINTY REMAINS QUITE HIGH FOR
STORM POTENTIAL FOR THE FIRST PART OF NEXT WEEK. GUIDANCE IS IN
GOOD AGREEMENT WITH THE SYNOPTIC SET UP FOR SUNDAY THROUGH EARLY
NEXT WEEK, BUT IT'S THE SUBTLE MESOSCALE FEATURES THAT DIFFER AND
WHERE THE MAIN UNCERTAINTY LIES. MODELS ARE ALSO IN BETTER
AGREEMENT WITH INCREASING MOISTURE SUNDAY INTO MONDAY COMPARED TO
LAST NIGHT AND THIS IN TURN IS LEADING TO HIGHER FORECAST
INSTABILITY AND EVEN POPS. THE RIDGE WILL CONTINUE TO SHIFT
FARTHER TO THE EAST DURING THIS TIME AS A TROUGH MOVES INTO THE
NORTHWESTERN U.S. THE MAIN SHORTWAVE WITHIN THE TROUGH WILL TRACK
ACROSS THE NORTHERN ROCKIES, BUT THE SOUTHERN FRINGES OF THE
TROUGH IS STILL LIKELY TO BRING INCREASED SUPPORT FOR SHOWERS AND
THUNDERSTORMS BY EARLY NEXT WEEK. MODELS SHOW A SEASONABLY STRONG
UPPER LEVEL JET SETTING UP FROM THE NORTHERN ROCKIES THROUGH THE
GREAT BASIN BY MONDAY WHICH IS EXPECTED TO PLACE OUR REGION WITHIN
A FAVORABLE AREA FOR ASCENT AS EARLY AS SUNDAY NIGHT AND
POTENTIALLY LASTING THROUGH NEXT TUESDAY OR WEDNESDAY.
OTHER UNKNOWNS FOR EARLY NEXT WEEK WILL BE THE PLACEMENT OF THE
BEST MOISTURE AND LIKELY THE SMALL SWATCH OF THE BEST INSTABILITY.
IT SEEMS LIKELY THERE WILL BE CONSIDERABLE CLOUDINESS SOMEWHERE
OVER OR NEAR EASTERN ARIZONA WHICH WILL LIMIT INSTABILITY, WHILE
THE BEST INSTABILITY/LOWER CIN SETS UP IN A MORE CLOUD-FREE AREA
TO THE WEST (SOUTH-CENTRAL AZ). THERE IS ALSO A DECENT CHANCE OF
HAVING SOME SORT OF MESOSCALE DISTURBANCE TRACKING NORTHWARD OUT
OF MEXICO AT SOME POINT EARLY NEXT WEEK WHICH WILL HELP TO
INITIATE STORM ACTIVITY. HOWEVER, UNCERTAINTY IS STILL TOO HIGH TO
BE ABLE TO PINPOINT THE TIMING AND THE POTENTIAL FOR STORMS, BUT
THERE IS MORE OPTIMISM FOR AT LEAST ONE OR TWO BUSY STORM DAYS
EARLY NEXT WEEK. NBM POPS HAVE INCREASED FOR EARLY NEXT WEEK AND
LOOK FAIRLY REASONABLE AT ANYWHERE FROM 30-70% ACROSS SOUTH-
CENTRAL AND EASTERN ARIZONA. IF MOISTURE AND INSTABILITY ENDS UP
ON THE HIGHER END OF GUIDANCE, WE ARE LIKELY TO HAVE TO WORRY
ABOUT SOME STRONG STORMS AND HEAVY RAINFALL/FLOODING POTENTIAL.
HOW LONG THIS INCREASED RAIN POTENTIAL MAY LAST IS ALSO UNCERTAIN
AS MODELS REALLY DON'T CHANGE THE SYNOPTIC SET UP THROUGH AT LEAST
NEXT THURSDAY OR FRIDAY. IT'S DOUBTFUL WE WILL HAVE GOOD RAIN
CHANCES EACH DAY NEXT WEEK, BUT IT ALSO SEEMS LIKELY THERE WILL
NOT BE ANY STRONG DRYING THAT WILL AFFECT THE AREA.
TEMPERATURES NEXT WEEK ARE ALMOST AS UNCERTAIN AS RAIN CHANCES AS
FAIRLY HIGH MODEL SPREAD IS SEEN FROM SUNDAY-WEDNESDAY, BUT WITH
AT LEAST A DOWNTREND IN TEMPERATURES. THE LATTER HALF OF NEXT WEEK
SHOWS EVEN HIGHER SPREAD, BUT WITH AN UPTREND IN TEMPERATURES WITH
READINGS EVENTUALLY WARMING BACK TO ABOVE NORMAL BY NEXT WEEKEND.
AVIATION
UPDATED AT 0005Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
THE ONLY AVIATION WEATHER CONCERN WILL BE THE POSSIBILITY OF A
DISTANT TS OUTFLOW CAUSING SUDDEN GUSTY WINDS OUT OF THE E/SE AND
POSSIBLY SOME BLDU/HZ IF STRONG ENOUGH. OCCASIONAL GUSTS BETWEEN
15-20 KTS ARE POSSIBLE OVER THE NEXT COUPLE OF HOURS BEFORE
TAPERING OFF. CHANCES FOR TSRA/SHRA DIRECTLY IMPACTING THE
TERMINALS REMAIN TOO LOW (10% OR LESS) TO INCLUDE IN THE TAF FOR
LATER THIS EVENING, BUT MOST LIKELY TIME WOULD BE AFTER 05-06Z.
FEW-SCT AND AT TIMES BKN MID AND HIGH CLOUD DECKS WILL PERSIST
THROUGH THE PERIOD.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
SE'RLY WINDS WILL CONTINUE AT KIPL WITH SPEEDS IN THE LOW TEENS
THROUGH THIS EVENING BEFORE LOWERING TO AOB 10 KT OVERNIGHT. KBLH
WILL MAINTAIN A SOUTHERLY FLOW WITH SPEEDS AOA 10KTS AND GUSTS
BETWEEN 20-25KT, GUSTS WILL RELAX FOR THE OVERNIGHT PERIOD,
HOWEVER SUSTAINED SPEEDS WILL REMAIN AOA 10KTS. GUSTS OF 20-25 KT
ARE EXPECTED AGAIN TOMORROW AFTERNOON. PERIODS OF FEW-SCT MID AND
HIGH CLOUD DECKS WILL CONTINUE.
FIRE WEATHER
ABOVE NORMAL TEMPERATURES WILL CONTINUE INTO THE WEEKEND, BUT
WITH SOME GRADUAL COOLING AS HUMIDITIES REMAIN SOMEWHAT ELEVATED.
ISOLATED CHANCES FOR SHOWERS AND A FEW THUNDERSTORMS CAN BE
EXPECTED THROUGH THE WEEKEND, WITH THE BEST CHANCES OVER THE
ARIZONA HIGH TERRAIN. RAIN CHANCES SHOULD IMPROVE DURING THE FIRST
HALF OF NEXT WEEK WITH TEMPERATURES EVENTUALLY DIPPING TO AROUND
AVERAGE FOR MID SEPTEMBER. MINRHS THROUGH EARLY NEXT WEEK WILL
GENERALLY BE BETWEEN 15-25% ACROSS THE WESTERN DISTRICTS AND
25-35% ACROSS THE EASTERN DISTRICTS. WINDS WILL SOMEWHAT FOLLOW
TYPICAL DIURNAL PATTERNS, BUT WITH MORE OF A SOUTH SOUTHWESTERLY
PREDOMINANT WIND ACROSS THE WESTERN DISTRICTS. DAILY AFTERNOON
GUSTS OF 20-25 MPH WILL BE COMMON ACROSS THE LOWER CO RIVER
VALLEY THROUGH THE WEEKEND BEFORE BECOMING MORE WIDESPREAD EARLY
NEXT WEEK.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING UNTIL 8 PM MST THIS EVENING FOR AZZ530-532-
533.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT THIS EVENING FOR CAZ562-566-
567-569-570.
SHORT TERM...RW
LONG TERM...KUHLMAN
AVIATION...BERISLAVICH
FIRE WEATHER...KUHLMAN
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