729
FXUS65 KPSR 121131
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
431 AM MST FRI SEP 12 2025
UPDATE
UPDATED AVIATION DISCUSSION
KEY MESSAGES
- SEASONAL TEMPERATURES NEARLY EVERY DAY WITH A GRADUAL WARMING
THROUGH EARLY NEXT WEEK.
- ISOLATED SHOWERS AND THUNDERSTORMS EXPECTED EARLY THIS MORNING
JUST EAST OF PHOENIX AND AGAIN THIS AFTERNOON ACROSS SOUTHERN
GILA COUNTY BEFORE MUCH DRIER CONDITIONS DEVELOP THIS WEEKEND
AND EXTEND INTO EARLY NEXT WEEK.
SHORT TERM /TODAY THROUGH SATURDAY/
IT IS THAT TIME OF YEAR WHEN THE MONSOON PATTERN STARTS TO BREAK
DOWN AND MORE COASTAL TROUGHS COME INTO PLAY. THE LARGE SCALE
WEATHER PATTERN ACROSS THE CONUS THIS MORNING IS HIGHLY AMPLIFIED
AND SOMEWHAT RESEMBLES AN OMEGA BLOCK, EXCEPT THE PATTERN IS NOT
STAGNANT. AN AMPLIFIED RIDGE IS CENTERED OVER THE PLAINS, WHILE AN
AMPLIFIED TROUGH IS IN PLACE ACROSS THE WESTERN CONUS. THIS
TROUGH, AND THE INCREASED WEST TO SOUTHWEST FLOW ACROSS THE DESERT
SOUTHWEST, HAS USHERED IN MUCH DRIER AIR ACROSS SOUTHEAST CA AND
WESTERN AZ. THE LINGERING MONSOONAL MOISTURE IS SITUATED MAINLY
ACROSS SOUTHEAST AZ, AND THERE WAS ENOUGH FOR SCATTERED SHOWERS
AND STORMS TO DEVELOP ACROSS THIS AREA YESTERDAY. TODAY WILL
LIKELY BE SIMILAR TO YESTERDAY WITH AFTERNOON SHOWERS AND STORMS
FOCUSED IN THE SAME AREAS, IF NOT A TOUCH FURTHER EAST AS THE
TROUGH BEGINS TRACKING EASTWARD ACROSS THE AREA. BETTER DYNAMIC
ASCENT TODAY, WITH JET SUPPORT AND COOLING ALOFT, AND INCREASED
SHEAR (SFC-6KM SHEAR MAGNITUDES UP TO 35-40 KTS) WILL SUPPORT THE
POTENTIAL FOR STRONG TO MARGINALLY SEVERE THUNDERSTORMS IN PARTS
OF SOUTHEAST AZ, INCLUDING SOUTHERN GILA COUNTY. A ROTATING STORM
CANNOT BE RULED OUT, BUT THE LOW LEVEL ENVIRONMENT WILL NOT BE
SUPPORTIVE OF TORNADOGENESIS. LOCALLY STRONG TO SEVERE WIND GUSTS,
BRIEF HEAVY RAIN, AND MARGINALLY SEVERE HAIL (0.5-1.0" DIAMETER)
WILL BE THE PRIMARY HAZARDS THIS AFTERNOON. PHOENIX WILL BE
ACTIVELY DRYING OUT THROUGH TODAY, WITH SURFACE DEW POINT
TEMPERATURES DROPPING FROM AROUND 60 DEGREES THIS MORNING TO THE
LOW TO MID 40S BY SUNSET. SO, EXPECTED AFTERNOON STORMS TO STAY
WELL EAST OF PHOENIX.
IN ADDITION TO THE AFTERNOON STORMS TODAY, SOME CONVECTION CANNOT
BE RULED OUT THIS MORNING, DEVELOPING IN NORTHERN PINAL AND
EASTERN MARICOPA COUNTIES. THIS POTENTIAL IS REFLECTED IN THE
FORECAST WITH UP TO 20-40% POPS. A HIGH-BASED CU FIELD DEVELOPED
SHORTLY AFTER MIDNIGHT IN THE MENTIONED AREAS AND SOME ISOLATED
STORMS DEVELOPED AROUND 230AM MST. MANY OF THE MOST RECENT RUNS
OF GLOBAL AND HI-RES MODELS BACKED OFF A BIT ON THIS MORNING
ACTIVITY, BUT ENOUGH MID-LEVEL CONVERGENCE AND SOME UPPER-LEVEL
JET SUPPORT HAS PROVED TO BE ENOUGH TO TRIGGER THE EARLY MORNING
STORMS. WITH MESOANALYSIS STILL SHOWING MUCAPE UP TO 500-1000 J/KG,
ANY ACTIVITY THIS MORNING WILL HAVE THE POTENTIAL TO PRODUCE
BRIEF HEAVY DOWNPOURS AND SOME STRONG GUSTY WINDS.
HEADING THROUGH SATURDAY MOST OF THE LINGERING MONSOONAL MOISTURE
WILL BE SCOURED OUT AS THE BASE OF THE TROUGH FULLY MOVES THROUGH
AZ. ENS AND GEFS SHOW PWAT ANOMALIES DROPPING TO AROUND 50% OF
NORMAL (MAGNITUDES AROUND 0.6") FOR THIS TIME OF YEAR BY THE END
OF THE DAY SATURDAY. SO, SATURDAY WILL FEATURE CLEAR SKIES WITH NO
RAIN EXPECTED. TEMPERATURES TODAY WILL BE RIGHT AROUND TO SLIGHTLY
BELOW DAILY AVERAGES, WITH THE TROUGH STARTING TO MOVE IN, AND
THEN TEMPERATURES COOL A FEW MORE DEGREES FOR SATURDAY, ESPECIALLY
ACROSS SOUTH-CENTRAL AZ, AS THE TROUGH MOVES THROUGH. ALL LOWER
DESERT LOCATIONS ARE FORECAST TO COME UP SHY OF 100 DEGREES ON
SATURDAY. PERHAPS A MORE WELCOME FEELING WILL BE LOWER DESERT
MORNING LOWS IN THE 70S TO MIDDLE 60S
LONG TERM /SUNDAY THROUGH FRIDAY/
FOLLOWING THE PASSAGE OF THE TROUGH ON SATURDAY, THE SYNOPTIC
PATTERN ACROSS THE DESERT SOUTHWEST WILL ENTER A RELATIVELY WEAK
WESTERLY FLOW REGIME, WITH NO CONSIDERABLE SYNOPTIC SCALE OR LARGE
SCALE FEATURES IMPACTING THE REGION, THROUGH AT LEAST THE FIRST
HALF OF NEXT WEEK. THIS WILL ALLOW TEMPERATURES TO REMAIN NEAR
SEASONAL LEVELS, WITH LOWER DESERT HIGH TEMPERATURES FORECAST TO
REACH RIGHT AROUND THE CENTURY MARK EACH DAY AND MORNINGS
CONTINUING TO START OUT IN THE 70S. GLOBAL ENSEMBLES DO SHOW A
GRADUAL TREND TOWARD POSITIVE 500MB HEIGHT ANOMALIES BY THE MIDDLE
OF NEXT WEEK, WHICH WILL SUPPORT A GRADUAL WARM-UP. LATEST NBM
FORECAST HAS HIGH TEMPERATURES RETURN TO A COUPLE OF DEGREES ABOVE
DAILY AVERAGES BY TUESDAY OR WEDNESDAY.
THIS WEAK FLOW PATTERN HEADING INTO EARLY NEXT WEEK WILL ALLOW
FOR AT LEAST A SLOW RETURN OF PBL MOISTURE FROM THE SOUTHEAST, BUT
AFTERNOON SHOWER AND STORM CHANCES DURING THE FIRST HALF OF NEXT
WEEK WILL MOSTLY FAVOR SOUTHEAST AZ, WITH NBM POP AT OR BELOW 10%
ACROSS SOUTH-CENTRAL AZ.
THE OVERALL PICTURE BECOMES LESS CLEAR BY THE SECOND HALF OF NEXT
WEEK WITH A HIGHLY VARIABLE FORECAST. THERE IS A HIGH DEGREE OF
UNCERTAINTY AS THE SYNOPTIC FLOW PATTERN LOOKS TO REMAIN PRETTY
WEAK AND MESSY AND THEN THERE IS THE POTENTIAL FOR TROPICAL
MOISTURE ADVECTION INTO THE REGION STEMMING FROM WHAT IS FORECAST
TO BECOME TROPICAL STORM MARIO OFF THE WEST COAST OF MEXICO. AS
OF NOW, MODELS GENERALLY FAVOR THE TRACK OF THIS SYSTEM REMAINING
OFF THE WESTERN COAST OF THE BAJA PENINSULA BEFORE EVENTUALLY
FALLING APART. HOWEVER, SOME MODELS WANT TO BRING REMNANT
TROPICAL MOISTURE INTO THE SOUTHWEST DESERTS AND COASTAL AREA,
WHICH COULD RESULT IN CONSIDERABLE CLOUD COVER AND EVEN RAIN
CHANCES. SUBTLE SHIFTS IN THE FORECAST COULD YIELD VASTLY
DIFFERENT FOREAST SOLUTIONS FOR THIS TIMEFRAME, SO HOW THIS
POTENTIAL SYSTEM EVOLVES WILL BE SOMETHING TO MONITOR IN THE
COMING DAYS. THE INTERQUARTILE RANGES ON FORECAST TEMPERATURES
FROM THE NBM ARE CURRENTLY AROUND 7-10 DEGREES ACROSS SOUTHERN AZ
AND SOCAL BEGINNING FRIDAY AND THE RANGES ON PWAT ARE AROUND
0.4-0.6".
AVIATION
UPDATED AT 1130Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
NO AVIATION CONCERNS ARE EXPECTED DURING THE TAF PERIOD. WINDS
WILL FOLLOW FAMILIAR DIURNAL TRENDS WITH GUSTS DURING THE
AFTERNOON AROUND 20-25 KTS. PRIOR TO THE USUAL AFTERNOON W'RLY
SHIFT, A FEW HOURS OF S'RLY CROSS WINDS SHOULD BE ANTICIPATED AT
KPHX AND KDVT. CONVECTIVE ACTIVITY WILL BE OBSERVED OVER THE HIGH
TERRAIN EAST OF THE PHOENIX METRO, BUT RAINFALL ACTIVITY SHOULD
REMAIN WELL OUTSIDE OF THE VICINITY OF THE TERMINALS.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO AVIATION CONCERNS ARE EXPECTED DURING THE NEXT 24 HOURS. WINDS
AT KIPL WILL REMAIN OUT OF THE W, WITH A BRIEF PERIOD OF GUSTS
UPWARDS OF 25 KTS THIS EVENING. AT KBLH, VRB WINDS WILL EVENTUALLY
SETTLE OUT OF THE SSW/SW BY THIS AFTERNOON. MOSTLY CLEAR SKIES
WILL PREVAIL THROUGH SATURDAY MORNING.
FIRE WEATHER
NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES WILL BE COMMON ACROSS
THE REGION THROUGH THIS WEEKEND THANKS TO AN AREA OF LOW PRESSURE
PASSING TO THE NORTH. OUTSIDE OF SOME BREEZY CONDITIONS THIS
AFTERNOON WITH PEAK GUSTS AROUND 20-25 MPH, WINDS OVER THE NEXT
SEVERAL DAYS WILL FAVOR FAMILIAR DIURNAL TRENDS. MOST OF THE
FORECAST AREA WILL REMAIN DRY, BUT SOME SLIGHT CHANCES OF WETTING
RAINS DO EXIST FOR THE FOOTHILLS AND HIGH TERRAIN EAST OF PHOENIX
BOTH THIS MORNING AND THIS AFTERNOON. MINRHS OVER THE NEXT FEW
DAYS ARE LIKELY TO RANGE FROM 10-15% ACROSS THE WESTERN DISTRICTS
TO 15-25% ACROSS THE EASTERN DISTRICTS. BY THIS WEEKEND, EVEN
DRIER CONDITIONS ARE EXPECTED.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...BENEDICT
LONG TERM...BENEDICT
AVIATION...RW
FIRE WEATHER...BENEDICT/LOJERO
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