912
FXUS65 KPSR 311006
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
306 AM MST MON AUG 31 2026
UPDATE
12Z AVIATION DISCUSSION.
KEY MESSAGES
- FLOOD WATCHES COVER MUCH OF SOUTHERN AND CENTRAL ARIZONA TODAY
AS PERIODS OF SHOWERS AND THUNDERSTORMS, CAPABLE OF PRODUCING
HEAVY RAINFALL, WILL REMAIN POSSIBLE.
- QUIET WEATHER UNDER MOSTLY CLEAR SKIES IS EXPECTED FOR TUESDAY
AND WEDNESDAY BEFORE POTENTIALLY ANOTHER MORE ACTIVE PERIOD OF
WEATHER MATERIALIZES BY THE END OF THE WEEK INTO THE WEEKEND.
- NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES ARE EXPECTED
THROUGHOUT MUCH OF THE WEEK.
SHORT TERM /TODAY INTO TONIGHT/
SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE TO IMPACT PORTIONS
OF SOUTH-CENTRAL AND EASTERN ARIZONA EARLY THIS MORNING, SOME OF
WHICH CONTINUE TO PRODUCE GUSTY (SUB-SEVERE) WIND GUSTS AND
LOCALIZED MODERATE RAINFALL. MUCH OF THE AVAILABLE INSTABILITY
THAT BUILT UP YESTERDAY HAS BEEN EXHAUSTED, BUT A NARROW CORRIDOR
OF 500-1000 J/KG OF ELEVATED CAPE REMAINS FROM EAST OF PHOENIX
NORTHWESTWARD THROUGH NORTHERN MARICOPA COUNTY INTO YAVAPAI
COUNTY. SHOWERS AND STORMS SHOULD MAINLY BE FOCUSED EAST OF
PHOENIX THROUGH THE REST OF THE MORNING WITH LOCALIZED RAINFALL
AMOUNTS OF AN INCH OR SO STILL A POSSIBILITY. THE FLOOD WATCH HAS
BEEN EXTENDED THROUGH NOON FOR PINAL AND GILA COUNTIES AND THE
EASTERN HALF OF THE PHOENIX METRO. GIVEN THIS ACTIVITY IS EXPECTED
THIS MORNING, IT IS LIKELY TO RUIN ANY CHANCES FOR ORGANIZED
ACTIVITY EAST OF PHOENIX DURING THE AFTERNOON HOURS.
LOOKING MORE BROADLY ACROSS THE REGION, THE MAIN DRIVER OF THE
SHOWER AND THUNDERSTORM ACTIVITY STEMS FROM A SHORTWAVE TROUGH
DIGGING EASTWARD THROUGH THE SOUTHERN HALF OF CALIFORNIA AND A
JET STREAK POSITIONED ACROSS NORTHERN ARIZONA THROUGH UTAH.
MOISTURE LEVELS ACROSS MOST OF ARIZONA REMAIN QUITE GOOD WITH LOW
LEVEL MIXING RATIOS OF 11-13 G/KG AND PWATS AROUND 150% OF NORMAL.
GIVEN THE CONTINUED BROAD FORCED ASCENT OVER MUCH OF THE AREA
PERSISTING THROUGH AT LEAST THIS AFTERNOON, ADDITIONAL ROUNDS OF
SHOWERS AND THUNDERSTORMS ARE LIKELY. THE BEST AREA OF FOCUS BY
THIS AFTERNOON SHOULD SWITCH TO OVER WESTERN MARICOPA COUNTY AND
LA PAZ COUNTY AND POSSIBLY INT NORTHERN YUMA COUNTY. THIS AREA
WILL LIKELY SEE A DECENT AMOUNT OF SUNSHINE LATER THIS MORNING AND
THIS AFTERNOON TO REBUILD THE INSTABILITY WITH HREF MUCAPES AGAIN
REACHING BETWEEN 1000-1500 J/KG FOR THIS AFTERNOON. CAMS
GENERALLY AGREE SCATTERED THUNDERSTORMS ARE LIKELY TO DEVELOP FROM
AROUND TUCSON THROUGH SOUTHERN/WESTERN MARICOPA COUNTY BY MID TO
LATE AFTERNOON WITH MORE ISOLATED STORMS ACROSS LA PAZ COUNTY.
SOME OF THESE STORMS MAY RESULT IN STRONG GUSTY WINDS, BUT THE
SEVERE THREAT REMAINS QUITE LOW. ADDITIONAL RAINFALL AMOUNTS OF UP
TO OR JUST OVER 1" WILL ALSO BE POSSIBLE IN THESE AREAS RESULTING
IN A RENEWED LOCALIZED FLASH FLOOD THREAT. FLOOD WATCHES HAVE
BEEN EXTENDED ACROSS WESTERN MARICOPA COUNTY THROUGH EARLY THIS
EVENING AND ALSO EXPANDED INTO LA PAZ AND NORTHERN YUMA COUNTIES
FOR THIS AFTERNOON THROUGH EARLY EVENING.
AS THE SHORTWAVE TROUGH LIFTS NORTHEASTWARD INTO NEVADA THIS
AFTERNOON AND INTO UTAH THIS EVENING, WE WILL GRADUALLY LOSE OUR
UPPER LEVEL SUPPORT LEAVING ONLY SLIGHT CHANCES FOR A FEW SHOWERS
DURING THE OVERNIGHT HOURS TONIGHT.
LONG TERM /TUESDAY THROUGH SUNDAY/
WEST SOUTHWESTERLY DRIER FLOW ALOFT WILL SPREAD OVER THE REST OF
ARIZONA BY TUESDAY WITH A BRIEF TIME PERIOD OF ANTICYCLONIC FLOW
ALOFT. THE DRIER AIR ALOFT IS EXPECTED TO MIX INTO THE BOUNDARY
LAYER BY TUESDAY AFTERNOON DROPPING SURFACE DEW POINTS INTO THE
40S ACROSS SOUTHEAST CALIFORNIA TO 55-60 DEGREES IN THE PHOENIX
AREA. ALTHOUGH WE CAN'T RULE OUT A FEW ISOLATED SHOWERS OR WEAK
THUNDERSTORMS TUESDAY AFTERNOON OVER THE MORE FAVORED HIGHER
TERRAIN LOCATIONS, THE CHANCES ARE ONLY AROUND 10-15%.
TEMPERATURES WILL REMAIN BELOW NORMAL ACROSS SOUTH-CENTRAL AND
EASTERN ARIZONA WITH LOWER DESERT HIGHS AT AROUND 100 DEGREES,
WHILE THE DRIER WESTERN LOWER DESERTS SHOULD REACH CLOSER TO 105
DEGREES.
THE DRYING ALOFT WILL CONTINUE TO A LESSER DEGREE INTO WEDNESDAY
AS LOW LEVEL MIXING RATIOS DROP TO 5-6 G/KG IN SOUTHEAST
CALIFORNIA TO 7-9 G/KG ACROSS MUCH OF ARIZONA. CHANCES FOR ANY
SHOWERS AND STORMS SHOULD BE SIMILAR OR EVEN LESS THAN TUESDAY'S
CHANCES. TEMPERATURES SHOULD ALSO WARM ANOTHER COUPLE OF DEGREES
UNDER SUNNY TO MOSTLY SUNNY SKIES.
FORECAST CONCERN IS INCREASING FOR THE POTENTIAL OF TROPICAL
MOISTURE SURGING NORTHWARD INTO THE REGION AS EARLY AS THURSDAY
NIGHT INTO FRIDAY, BUT MORE SO FOR THE COMING WEEKEND. NHC SHOWS A
TROPICAL DISTURBANCE CURRENTLY NEAR 10N AND 107W WITH A 90%
CHANCE OF CYCLONE FORMATION THIS WEEK AND LIKELY TRACKING
NORTHWARD OFF THE COAST OF BAJA BY FRIDAY INTO THE WEEKEND. THERE
IS STILL A LOT OF UNCERTAINTY WITH THIS POTENTIAL TROPICAL
SYSTEM, BUT MODEL GUIDANCE HAS BEEN COMING TO A BIT BETTER
CONSENSUS THE LAST SEVERAL MODEL RUNS. ROUGHLY 90% OF THE GEFS AND
EPS MEMBERS NOW SHOW PWATS INCREASING TO 1.8-2.2" OVER PORTIONS OF
OUR AREA BY FRIDAY OR SATURDAY. GIVEN THIS LIKELY INCREASE IN
MOISTURE, POPS HAVE GONE UP STARTING FRIDAY AND CONTINUE THROUGH
THE WEEKEND. IT WILL LIKELY BE AT LEAST 2 OR 3 MORE DAYS UNTIL WE
HAVE A GOOD IDEA ON WHAT WOULD LIKELY HAPPEN LATE THIS WEEK.
GETTING TROPICAL MOISTURE INTO OUR REGION IS DEFINITELY NOT
UNUSUAL, BUT MANY TIMES WHEN IT HAPPENS WE STRUGGLE TO BUILD
INSTABILITY DUE TO EXTENSIVE CLOUDINESS AND POOR LAPSE RATES.
HOWEVER, IT SEEMS QUITE LIKELY A PACIFIC TROUGH WILL BE SITUATED
ALONG OR JUST OFF THE WEST COAST WHICH MAY PROVIDE FOR ENOUGH
UPPER LEVEL FORCED ASCENT TO OVERCOME THE LIKELY LACKLUSTER
INSTABILITY. WE WILL CONTINUE TO WATCH THIS THROUGHOUT THE WEEK AS
IT VERY WELL COULD LEAD TO ANOTHER ROUND OF HEAVY RAINFALL AT
SOME POINT.
AVIATION
UPDATED AT 1000Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
CURRENT RADAR MOSAIC DEPICTS A BAND OF SHOWERS WITH EMBEDDED
LIGHTNING STRIKES CONTINUING TO STREAM N-NE INTO SOUTHCENTRAL AZ.
THIS TREND WILL CONTINUE THROUGH SUNRISE WITH A POTENTIAL
REINVIGORATION OF SHRA/TSRA FOR A FEW HOURS (MAINLY BETWEEN
15Z-18Z). THE MOST LIKELY TERMINALS TO SEE ANY VCTS OR TS WILL BE
KIWA, BUT A FEW LIGHTNING STRIKES CANNOT BE RULED OUT AT KPHX
THROUGH THE MORNING HOURS. BY LATER THIS AFTERNOON, STORM ACTIVITY
SHOULD LARGELY COME TO AN END ACROSS THE PHOENIX METRO. WINDS
WILL LIKELY MAINTAIN AN E TO SE COMPONENT THROUGH THE PERIOD WITH
SOME GUSTS INTO THE TEENS TO AROUND 20 KTS. SCT TO BKN MID TO HIGH
CLOUDS WILL PREVAIL OVER THE REGION WITH GRADUAL CLEARING
ANTICIPATED BY THIS EVENING.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION CONCERNS ARE EXPECTED AT THE SE CALIFORNIA
TERMINALS. AT KIPL, WINDS WILL FLUCTUATE BETWEEN SOUTHEASTERLY
DURING THE DAYTIME AND WESTERLY AFTER SUNSET. AT KBLH, WINDS WILL
MAINTAIN A SOUTHERLY DIRECTION THROUGH THE TAF PERIOD. SPEEDS
WILL RANGE MOSTLY BETWEEN 10-13 KTS WITH INTERMITTENT GUSTS AROUND
20 KTS AT KBLH THIS AFTERNOON. ASIDE FROM A FEW PASSING HIGHT
CLOUDS, SKIES SHOULD REMAIN MOSTLY CLEAR.
FIRE WEATHER
ELEVATED MOISTURE AND PERIODS OF SHOWERS AND THUNDERSTORMS WILL
CONTINUE TODAY, MAINLY ACROSS THE EASTERN DISTRICTS. GUSTY WINDS,
HEAVY RAINFALL, AND LOCALIZED FLOODING WILL REMAIN A THREAT. DRIER
CONDITIONS WILL MOVE IN BEGINNING TUESDAY WITH RAIN CHANCES
MOSTLY ENDING THROUGH MIDWEEK. EXPECT MINRHS OF 15-25% ACROSS THE
WESTERN DISTRICTS TO 35-50% OVER THE EASTERN DISTRICTS TODAY
BEFORE FALLING BACK TO 15-25% AREAWIDE BY WEDNESDAY. TEMPERATURES
WILL RANGE FROM AROUND NORMAL OVER WESTERN DISTRICTS TO SLIGHTLY
BELOW NORMAL OVER THE EASTERN DISTRICTS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...FLOOD WATCH FROM NOON MST TODAY THROUGH THIS EVENING FOR AZZ531-
533-539.
FLOOD WATCH THROUGH THIS EVENING FOR AZZ534-537-538-540-554-559.
FLOOD WATCH UNTIL NOON MST TODAY FOR AZZ541>553-555>558-560>563.
CA...NONE.
SHORT TERM...KUHLMAN
LONG TERM...KUHLMAN
AVIATION...SALERNO
FIRE WEATHER...KUHLMAN
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