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FXUS65 KPSR 031817
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1117 AM MST THU SEP 3 2026
UPDATE
UPDATED 18Z AVIATION DISCUSSION.
KEY MESSAGES
- ISOLATED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ACROSS
SOUTH CENTRAL ARIZONA LATE THIS AFTERNOON.
- TROPICAL MOISTURE WILL ARRIVE INTO THE REGION TONIGHT INTO
FRIDAY, FURTHER INCREASING RAIN CHANCES MAINLY ACROSS THE
FOOTHILLS AND HIGH TERRAIN AREAS EAST OF PHOENIX BEFORE CHANCES
SHIFT INTO SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA THIS
WEEKEND.
- TEMPERATURES REMAIN IN A NEAR TO BELOW NORMAL CATEGORY FOR THE
REST OF THIS WEEK AND INTO THE WEEKEND, RESULTING IN WIDESPREAD
MINOR HEAT RISK AND LOCALIZED AREAS OF MODERATE HEAT RISK.
SHORT TERM /TODAY THROUGH FRIDAY/
LATEST GOES-18 MID-LVL WV IMAGERY AND 500 MB STREAMLINE ANALYSIS
REVEALS A BROAD TROUGH OF LOW PRESSURE ENCOMPASSING THE PACIFIC NW
AND INTERMOUNTAIN WEST WHILE A RIDGE OF HIGH PRESSURE EXTENDS
FROM THE SOUTHERN PLAINS INTO THE SOUTHEASTERN U.S. OUR FORECAST
AREA IS SITUATED BETWEEN BOTH OF THESE FEATURES UNDER A PROMINENT
FETCH OF DRY SW FLOW ALOFT. MEANWHILE, NOW CAT 2 HURRICANE MARIE
IS CHURNING OVER THE E PACIFIC, WELL SOUTHWEST OF THE TIP OF THE
BAJA PENINSULA. MOISTURE ADVECTION IS ONGOING WELL OUT AHEAD OF
THE MAIN CIRCULATION INTO N SONORA MX AND BEGINNING TO ENCROACH ON
SOUTHERN AZ. MOISTURE WILL CONTINUE TO BE TRANSPORTED NWD INTO
CENTRAL AZ WITH PWAT VALUES EXPECTED TO CLIMB TO AROUND 1.5-1.7"
LATER TODAY THROUGH EARLY FRIDAY, HOWEVER THERE IS EXPECTED TO BE
A WELL DEFINED MOISTURE GRADIENT FROM E TO W ACROSS AZ. MUCH DRIER
AIR ASSOCIATED WITH THE TROUGHING TO THE NW OF OUR REGION WILL
EXTEND INTO SE CALIFORNIA AND SOUTHWEST AZ THROUGH FRIDAY WHICH
WILL REALLY LIMIT RAIN CHANCES ACROSS THE WESTERN HALF OF THE
FORECAST AREA UNTIL BETTER MOISTURE ARRIVES THIS WEEKEND. NBM POPS
HAVE CONTINUED TO SHIFT EWD WITH EACH SUBSEQUENT RUN AND THE MAIN
FOCUS FOR SHOWER AND STORM ACTIVITY NOW LOOKS TO BE EAST OF
PHOENIX, MAINLY IN THE FOOTHILLS OF MARICOPA COUNTY AND S GILA
COUNTY. THIS ALIGNS WITH THE LATEST WPC ERO FOR DAY 2 (FRIDAY)
WITH AN EASTWARD SHIFT IN THE SLIGHT RISK WHICH MOSTLY ENCOMPASSES
THE TWC FORECAST AREA AND CLIPS S GILA COUNTY. NONETHELESS, CAMS
STILL INDICATE A FEW POP UP ISOLATED SHOWERS AND STORMS IN CENTRAL
MARICOPA COUNTY INCLUDING THE PHOENIX METRO AREA LATE TODAY
THROUGH EARLY FRIDAY AND AGAIN FRIDAY AFTERNOON/EVENING. SOME
STORMS COULD PRODUCE GUSTY WIND AND LOCALIZED FLASH FLOODING.
DUE TO THE PRESENCE OF TROUGHING TO OUR WEST MAINTAINING 500 MB
HGHTS WITHIN A 587-590 DAM RANGE, TEMPERATURES WILL BE WITHIN A
DEGREE OR TWO OF DAILY NORMALS THROUGH THE END OF THIS WEEK. LOWER
DESERT HIGHS WILL GENERALLY RANGE FROM THE UPPER 90S TO AROUND
105 DEGREES EACH AFTERNOON, FOLLOWING MORNING LOWS FROM THE UPPER
70S TO MIDDLE 80S. THE WEST COAST TROUGH WILL ALSO PROMOTE A
TIGHTER MID LVL PRESSURE GRADIENT OVER SOUTHEAST CA AND WESTERN AZ
WHICH WILL LEAD TO CONTINUED BREEZY TO LOCALLY WINDY CONDITIONS
ACROSS THE IMPERIAL AND LOWER COLORADO RIVER VALLEYS. GUSTS COULD
REACH UPWARDS OF 25-30 MPH IN THE AFOREMENTIONED AREAS AND
POTENTIALLY AS HIGH AS 40 MPH IN FAR SW IMPERIAL COUNTY.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
GLOBAL MODELS ARE COMING INTO SOMEWHAT BETTER AGREEMENT WITH THE
PATTERN EVOLUTION THIS WEEKEND. BOTH THE ECMWF AND GFS SHOW HIGH
PRESSURE STRENGTHENING OVER THE SOUTHERN PLAINS WITH THE WESTERN
PERIPHERY OF THE RIDGE EXTENDING OVER E AZ AND NM. THIS WILL CAUSE
THE SUBTROPICAL JET TO SHIFT WWD BEGINNING SATURDAY, SETTING UP
BETTER MOISTURE ADVECTION OVER SOUTHEAST CA AND SOUTHWEST AZ. NBM
POPS ARE STILL NOT OVERLY IMPRESSIVE, MAINLY IN THE 20-30% RANGE
ON SATURDAY, HOWEVER THE GEFS/GFS INDICATES A FINAL SLUG OF
MOISTURE FROM MARIE BEING PULLED INTO SOUTHEAST CA ON SUNDAY WITH
PWATS RISING ABOVE 2.0". THEREFORE WE WILL HAVE TO MONITOR FOR
HEAVIER RAINFALL POTENTIAL IN PORTIONS OF SE CALIFORNIA INCLUDING
JOSHUA TREE NP ON SUNDAY. ELSEWHERE, ACROSS SOUTHCENTRAL AZ, RAIN
CHANCES LOOK TO BE MEAGER DUE TO MORE EXTENSIVE CLOUD COVER AND
VERY LOW INSTABILITY. THE LATEST WPC QPF FIELD SHOWS A LOCAL
MINIMUM IN RAINFALL TOTALS (<0.10") IN SOUTHCENTRAL AZ INCLUDING
THE PHOENIX METRO THROUGH THIS WEEKEND. BY EARLY NEXT WEEK, THERE
ARE LARGE DISCREPANCIES IN THE RIDGE/TROUGH POSITIONING WHICH WILL
COMPLICATE THE PRECIPITATION FORECAST, BUT THERE WILL STILL BE
ADEQUATE MOISTURE ACROSS OUR REGION WHICH WILL KEEP LOW END POPS
IN PLACE ACROSS EASTERN AND SOUTHEASTERN AZ MONDAY AND TUESDAY
WITH POTENTIALLY BETTER PRECIPITATION CHANCES ARRIVING WEDNESDAY.
THE TEMPERATURE FORECAST THIS WEEKEND INTO EARLY NEXT WEEK
REMAINS LARGELY UNCHANGED, ALTHOUGH THERE WILL LIKELY BE A GRADUAL
INCREASE FROM NEAR NORMAL TEMPERATURES ON SATURDAY TO SLIGHTLY
ABOVE NORMAL TEMPERATURES SUNDAY INTO EARLY NEXT WEEK AS RIDGING
STRENGTHENS OVER THE REGION. DEPENDING ON HOW STRONG THE RIDGE
GETS, NBM TEMPS COULD CLIMB A FEW MORE DEGREES IN SUBSEQUENT RUNS
AND IT IS NOT OUT OF THE QUESTION THAT WE COULD SEE LOWER DESERT
HIGHS APPROACHING 110 DEGREES AS INDICATED BY THE NBM 75TH
PERCENTILE ON MONDAY AND TUESDAY.
AVIATION
UPDATED AT 1816Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
THE MAIN AVIATION WEATHER IMPACT AND FORECAST UNCERTAINTY THIS TAF
PERIOD WILL BE THE POTENTIAL FOR 1-3 PERIODS OF VCTS/TSRA/VCSH
STARTING AS EARLY AS 21-22Z THIS AFTERNOON AND GOING THROUGH
13-14Z FRIDAY MORNING. PROB30 TS WAS ADDED TO KPHX FOR THIS
AFTERNOON, WITH THE POTENTIAL FOR A SHOWER OR STORM TO POP UP OVER
THE ESTRELLA MTNS. CONFIDENCE IS A LITTLE BETTER IN SHOWER AND
STORM DEVELOPMENT FRIDAY MORNING, BUT THIS ACTIVITY MAY STAY JUST
SE AND E OF TERMINALS. AN ISOLATED SHOWER OR STORM ALSO CANNOT BE
RULED OUT IN THE MIDDLE OF THE NIGHT. WINDS WILL FAVOR A S'RLY
COMPONENT FOR MUCH OF THE AFTERNOON WITH A VEERING TOWARD SW BY
22-23Z. WINDS WINDS WILL EVENTUALLY TURN BACK E'RLY TONIGHT,
LIKELY AFTER MIDNIGHT AND SPEEDS WILL INCREASE UP TO 8-13 KT BY
14-16Z. FEW TO SCT CLOUDS WILL BE COMMON WITH LOWEST DECKS AROUND
8-12 KFT THROUGH MOST OF THE TAF PERIOD.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
BREEZY CONDITIONS, ONCE AGAIN DURING THE AFTERNOON AND EVENING,
HOURS WILL BE THE MAIN AVIATION WEATHER IMPACT. WINDS AROUND 5-10
KT ARE EXPECTED THROUGH EARLY AFTERNOON BEFORE INCREASING UP TO
9-14 KT WITH GUSTS UP TO 20-25 KT LATE THIS AFTERNOON THROUGH THIS
EVENING. WIND DIRECTIONS WILL MOSTLY MAINTAIN A WESTERLY TO
SOUTHWESTERLY COMPONENT AT KIPL WHILE KBLH SWITCHES BETWEEN
SOUTHERLY AND SOUTHWESTERLY DIRECTIONS. MOSTLY CLEAR SKIES WILL
PREVAIL.
FIRE WEATHER
ISOLATED TO WIDELY SCATTERED SHOWERS AND STORMS WILL BE POSSIBLE
IN SOUTHCENTRAL AZ LATER TODAY THROUGH FRIDAY. RAIN CHANCES WILL
EXPAND WESTWARD THROUGH THIS WEEKEND, BECOMING FOCUSED OVER THE
WESTERN DISTRICTS SATURDAY AND SUNDAY. THE BEST CHANCES FOR
WETTING RAINFALL WILL BE OVER THE HIGHER TERRAIN AREAS OF EASTERN
AND SOUTHEASTERN AZ. AFTERNOON MINIMUM HUMIDITIES WILL RANGE FROM
7-15% ACROSS SOUTHEAST CA AND BETWEEN 20-35% FOR THE REMAINDER OF
THE REGION THROUGH FRIDAY AND WILL LIKELY INCREASE ABOVE 25%
AREAWIDE THIS WEEKEND. OVERNIGHT RECOVERIES WILL RANGE FROM POOR
ACROSS THE WESTERN DESERTS AND GOOD TO EXCELLENT ACROSS THE
EASTERN DISTRICTS. DAYTIME WINDS WILL REMAIN ELEVATED OUT OF THE
SOUTH TO SOUTHWEST, WITH THE STRONGEST GUSTS IN SOUTHEAST CA AND
ALONG THE LOWER COLORADO RIVER VALLEY PEAKING BETWEEN 20-30 MPH
DURING THE AFTERNOON/EARLY EVENING.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...SALERNO
LONG TERM...SALERNO
AVIATION...BENEDICT
FIRE WEATHER...WHITTOCK/SALERNO
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