004
FXUS65 KPSR 251717
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1017 AM MST MON AUG 25 2025
UPDATE
UPDATED 18Z AVIATION DISCUSSION.
KEY MESSAGES
- A FLOOD WATCH HAS BEEN ISSUED FOR MUCH OF SOUTHWEST ARIZONA AND
SOUTHEAST CALIFORNIA FOR THIS AFTERNOON AND EVENING. WIDESPREAD
SHOWERS AND THUNDERSTORMS WILL BE CAPABLE OF PRODUCING HEAVY
RAINFALL LOCALIZED FLOODING.
- SHOWERS AND THUNDERSTORMS ARE LIKELY OVER MUCH OF THE AREA TODAY
AND POSSIBLY AGAIN ON TUESDAY. GUSTY WINDS, BLOWING DUST, HEAVY
RAINFALL, AND LOCALIZED FLOODING WILL ALL BE POSSIBLE,
ESPECIALLY THROUGH THIS EVENING.
- TEMPERATURES WILL COOL OFF OVER THE NEXT COUPLE OF DAYS,
DROPPING TO BELOW NORMAL STARTING TUESDAY.
SHORT TERM /TODAY THROUGH TUESDAY/
THE MAIN FORECAST CONCERN OVER THE NEXT DAY OR TWO WILL BE THE
POTENTIAL FOR HEAVY RAINFALL AND LOCALIZED FLASH FLOODING GIVEN
THE STRONG MOISTURE ADVECTION WHICH CONTINUES OVER MUCH OF THE
REGION AND INCREASED FORCING FROM A PACIFIC TROUGH COMING IN FROM
THE WEST. IN ADDITION TO THE HEAVY RAINFALL POTENTIAL, GUIDANCE IS
SUGGESTING WE MAY SEE A FEW STRONG TO SEVERE WIND GUSTS ALONG
WITH THE POTENTIAL FOR STRONG OUTFLOW WINDS AND BLOWING DUST
FOCUSED ACROSS SOUTH-CENTRAL AND SOUTHERN ARIZONA.
THE SYNOPTIC PICTURE OVER THE PAST COUPLE OF DAYS HAS SLOWLY
CHANGED WITH THE SUBTROPICAL HIGH CENTERED JUST TO OUR NORTHEAST
WEAKENING WHILE AN UPPER LEVEL TROUGH IS STARTING TO DIG ALONG AND
JUST OFF THE CALIFORNIA COAST. THIS IS LEADING TO INCREASED
SOUTHEASTERLY FLOW INTO THE REGION PULLING UP GOOD MOISTURE,
PUSHING PWATS CURRENTLY TO BETWEEN 1.3-1.6" ACROSS THE LOWER
DESERTS. OVER THE NEXT 12 HOURS OR SO, MOISTURE ADVECTION WILL
CONTINUE BUMPING PWATS MORE INTO A 1.5-1.8" RANGE WHILE MIXING
RATIOS RISE TO A RESPECTABLE 10-12 G/KG.
ISOLATED SHOWERS AND THUNDERSTORMS ARE ALREADY DEVELOPING OVER
PORTIONS OF THE AREA, SPECIFICALLY PHOENIX AND SOUTHERN YUMA
COUNTY. AS MOISTURE CONTINUES TO IMPROVE AND DIFLUENCE ALOFT
INCREASES FROM THE INCOMING TROUGH BY THIS AFTERNOON, WE ARE
LIKELY TO SEE CLUSTERS OF SHOWERS AND THUNDERSTORMS TO FORM. HI-
RES CAMS SEEM TO BE ALL OVER THE PLACE AS FAR AS PLACEMENT OF
CONVECTION LATER TODAY, BUT THERE AT LEAST SEEMS TO BE AN OVERLAP
ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA. THIS AREA
SHOULD ALSO HAVE THE HIGHEST MOISTURE AND INSTABILITY, ALONG WITH
THE POTENTIAL FOR SOME TRAINING OF CONVECTIVE CELLS. GIVEN THE
GOOD MOISTURE AND EXPECTED INSTABILITY, IT SEEMS FAIRLY LIKELY
SOME AREAS WILL SEE HEAVY RAINFALL AND THE POTENTIAL FOR LOCALIZED
FLOODING FOCUSED MORE ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST
ARIZONA. WE HAVE LOFTED A FLOOD WATCH FOR A GOOD PORTION OF THIS
AREA FROM EARLY AFTERNOON THROUGH MID EVENING WITH RAINFALL
AMOUNTS OF 1-2" POSSIBLE WITHIN THIS AREA.
FROM PHOENIX AND AREAS TO THE EAST OF PHOENIX, MOISTURE WILL BE A
BIT MORE LIMITED, BUT STILL FAIRLY GOOD CONSIDERING WHAT WE HAVE
HAD LATELY. INSTABILITY SHOULD ALSO BE LOWER THAN THE WESTERN
DESERTS, BUT DCAPES SHOULD BE HIGHER PROMOTING BETTER CHANCES FOR
STRONG OUTFLOWS. CAMS HAVE BEEN QUITE UNCERTAIN WITH THE POTENTIAL
SHOWER AND THUNDERSTORM COVERAGE, BUT TRENDS HAVE MOSTLY AGREED
ON SOME SORT OF COMPLEX OF SHOWERS AND STORMS COMING OUT OF TUCSON
REACHING THE PHOENIX AREA LATE IN THE AFTERNOON AND EARLY
EVENING. THIS WILL LIKELY PROMOTE SOME BLOWING DUST ACROSS SOUTH-
CENTRAL ARIZONA, PARTICULARLY TO THE SOUTH OF PHOENIX. WE ALSO
CAN'T RULE OUT SOME LOCALIZED HEAVY RAINFALL AND MINOR FLOODING,
BUT THE CHANCES SEEM TO BE TOO LOW TO INCLUDE IN THE FLOOD WATCH.
BY LATE THIS EVENING INTO TONIGHT, GUIDANCE GENERALLY AGREES ON A
DIMINISHING THREAT FOR SHOWER AND THUNDERSTORM ACTIVITY. FORECAST
UNCERTAINTY INCREASES FURTHER FOR TUESDAY AS WE ARE LIKELY TO BE
UNDER A SCENARIO WHERE WE HAVE WORKED OVER THE ATMOSPHERE A GOOD
DEAL TODAY LEAVING LESS INSTABILITY FOR TUESDAY. THERE IS ALSO
DIFFERENCES IN THE AMOUNT OF MOISTURE AVAILABLE FOR TUESDAY WITH
THE GEFS INDICATING SOME DRYING ALREADY OCCURRING WHILE THE EPS
KEEPS THE 1.5-1.7" PWATS IN PLACE. NBM POPS ALSO SEEM WAY OUT OF
WHACK FOR TUESDAY PROVIDING HIGHER CHANCES ON TUESDAY VERSUS
TODAY. WE HAVE LOWERED POPS TUESDAY TO MOSTLY SHOW 30-50% CHANCES
ACROSS THE LOWER DESERTS TO 50-70% OVER THE EASTERN ARIZONA HIGHER
TERRAIN. TUESDAY MAY END UP PLAYING OUT WELL FOR THOSE AREAS THAT
DO NOT RECEIVE MUCH CONVECTION TODAY, SPECIFICALLY FROM PHOENIX
AND AREAS TO THE EAST OF PHOENIX. WE ALSO CAN'T RULE OUT A THREAT
FOR HEAVY RAINFALL AND LOCALIZED FLOODING ON TUESDAY FOCUSED MORE
OVER THE EASTERN PORTION OF THE REGION.
TEMPERATURES TODAY WILL DROP FROM WHAT WE SAW OVER THE WEEKEND,
BUT DAYTIME HIGHS TODAY ARE LIKELY TO STILL REACH TO WITHIN A
DEGREE OR TWO OF NORMALS. THE INCREASED MOISTURE AND RAIN COOLED
AIR SHOULD BRING DOWN TEMPERATURES FURTHER FOR TUESDAY WITH HIGHS
ANYWHERE FROM THE MID 90S TO AROUND 100 DEGREES.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
BY WEDNESDAY, THE INFLUENCES OF THE SUBTROPICAL HIGH WILL BE MUCH
LESS AS IT SHIFTS ITS CENTER OVER THE SOUTHERN PLAINS. AT THE SAME
TIME, THE PACIFIC TROUGH WILL NUDGE INTO AT LEAST WESTERN
PORTIONS OF OUR REGION LEADING TO LOWER HEIGHTS AND TURNING OUR
FLOW OUT OF THE SOUTHWEST. THIS WILL BRING IN A GOOD AMOUNT OF
DRIER AIR WEDNESDAY INTO THURSDAY, EVENTUALLY SCOURING OUT MUCH OF
OUR LOW LEVEL MOISTURE BY FRIDAY. HOWEVER, THE LINGERING MOISTURE
ON WEDNESDAY SHOULD STILL BE ENOUGH TO ALLOW FOR SOME ISOLATED
SHOWER AND THUNDERSTORM ACTIVITY LIKELY FOCUSED OVER HIGHER
TERRAIN AREAS. AS THE DRY AIR REALLY SETTLES IN BY THURSDAY, WE
SHOULD EXPECT ONLY VERY MINIMAL RAIN CHANCES ACROSS THE EASTERN
ARIZONA HIGH TERRAIN. THIS WESTERLY FLOW DRY PATTERN IS LIKELY TO
CONTINUE THROUGH THE UPCOMING WEEKEND KEEPING MUCH IF NOT ALL OF
OUR AREA DRY.
TEMPERATURES SHOULD CONTINUE TO RUN SLIGHTLY BELOW NORMAL FOR
WEDNESDAY AND THURSDAY BEFORE SOME GRADUAL WARMING PUSHES HIGHS
BACK INTO THE NORMAL RANGE OF 102-105 DEGREES BY FRIDAY.
ADDITIONAL WARMING IS FAVORED OVER THE WEEKEND AS THE SUBTROPICAL
HIGH SOMEWHAT NUDGES BACK INTO OUR REGION. THE NBM SUGGESTS
DAYTIME HIGHS WARMING BACK TO BETWEEN 104-108 DEGREE RANGE FOR
THE WEEKEND.
AVIATION
UPDATED AT 1720Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
CONFIDENCE CONTINUES TO INCREASE FOR IMPACTS FROM THUNDERSTORMS
LATER THIS AFTERNOON INTO THE EVENING AT VALLEY TERMINALS. A
COMPLEX OF THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS SOUTHERN
AZ THIS AFTERNOON AND LIFT NORTH ACROSS THE VALLEY BY EARLY
EVENING. THESE STORMS WILL PUSH OUT A STRONG OUTFLOW FROM THE
SOUTH WITH A GENERAL TIMING OF THE INTIAL GUSTY WIND SHIFT
EXPECTED BETWEEN 23Z-01Z. BLOWING DUST IS ANTICIPATED WITH THIS
OUTFLOW DUE TO THE FAVORABLE SSE DIRECTION REDUCING SURFACE AND
SLATWISE VISIBILITIES. THIS ENTIRE COMPLEX OF STORMS WILL LIKELY
(40-60%) SHIFT INTO THE VALLEY. HAVE ADDED TEMPO GROUP FOR
THUNDERSTORMS AT ALL TERMINALS, GENERALLY IN THE 01Z-05Z
TIMEFRAME. SOME SHOWERS WILL LINGER INTO OVERNIGHT WITH LINGERING
SCT/BKN CLOUD COVER.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
SHRA/TSRA WITH GUSTY WINDS WILL BE THE PRIMARY HAZARD TO
OPERATIONS THROUGH TONIGHT UNDER PERIODS OF MID/HIGH CIGS ABOVE 8K
FT AGL. CONFIDENCE IS FAIR THAT ANOTHER ROUND OF TSRA SIMILAR TO
YESTERDAY WILL DEVELOP THIS AFTERNOON SOUTH AND WEST OF KIPL.
GUSTY WINDS WITH BLOWING DUST AND LOCALLY HEAVY RAINFALL ARE
POSSIBLE BEFORE LIFTING AWAY FROM THE AREA IN THE EVENING, MAINLY
IN THE 22-01Z TIMEFRAME.
FIRE WEATHER
ABUNDANT MOISTURE AND PERIODS OF SHOWERS AND THUNDERSTORMS ARE
EXPECTED EARLY THIS WEEK. THE BEST RAINFALL CHANCES TODAY ARE
LIKELY TO BE FOCUSED ACROSS THE WESTERN DISTRICTS BEFORE SHIFTING
OVER THE EASTERN DISTRICTS ON TUESDAY. STRONG GUSTY WINDS, HEAVY
RAINFALL AND LOCALIZED FLOODING WILL BE POSSIBLE, ESPECIALLY
TODAY. ELEVATED HUMIDITIES WILL LEAD TO MINRHS BETWEEN 25-40%
TODAY AND TUESDAY BEFORE GRADUALLY LOWERING BEGINNING WEDNESDAY.
TEMPERATURES WILL DROP INTO THE NORMAL RANGE TODAY AND TO BELOW
NORMAL STARTING TUESDAY. DRYING CONDITIONS LATER THIS WEEK SHOULD
MOSTLY END RAIN CHANCES BY THURSDAY WITH MINRHS DROPPING BACK INTO
THE TEENS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...FLOOD WATCH UNTIL 9 PM MST THIS EVENING FOR AZZ530>533-535-536-
539-559.
BLOWING DUST ADVISORY FROM 2 PM THIS AFTERNOON TO 6 PM MST THIS
EVENING FOR AZZ539-551-553-554-559.
CA...FLOOD WATCH UNTIL 9 PM PDT THIS EVENING FOR CAZ562>567-569-570.
SHORT TERM...KUHLMAN
LONG TERM...KUHLMAN
AVIATION...FRIEDERS
FIRE WEATHER...KUHLMAN
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