781
FXUS65 KPSR 271816
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1116 AM MST THU AUG 27 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- EXTREME HEAT WARNINGS REMAIN IN EFFECT THROUGH SATURDAY WITH
AREAS OF MAJOR TO EXTREME HEAT RISK, DESPITE TEMPERATURES
SLOWLY DECREASING.
- TODAY AND FRIDAY WILL BRING LOW END CHANCES FOR SHOWERS AND A
FEW THUNDERSTORMS, FOCUSED MORE ACROSS SOUTHERN AND CENTRAL
ARIZONA.
- A LOW PRESSURE SYSTEM NEARING THE REGION OVER THE WEEKEND WILL
BRING MUCH BETTER CHANCES FOR RAIN, INCLUDING A CHANCE OF STRONG
TO SEVERE STORMS ACROSS SOUTHERN ARIZONA FROM MAINLY ON SUNDAY
OR MONDAY.
SHORT TERM /TODAY THROUGH FRIDAY/
AN UNSEASONABLY STRONG SUBTROPICAL RIDGE REMAINS POSITIONED
DIRECTLY OVER THE DESERT SOUTHWEST, BUT IT IS GETTING INFILTRATED
BY A GOOD AMOUNT OF HIGH LEVEL MOISTURE PEELED AWAY FROM THE
REMNANTS OF TC ISELLE. WATER VAPOR IMAGERY SHOWS A DECENT STREAM
OF UPPER LEVEL MOISTURE JUST WEST AND SOUTHWEST OF NORTHERN BAJA
INTO ARIZONA. WE ANTICIPATE PARTLY TO MOSTLY CLOUDY SKIES ACROSS
SOUTHEAST CALIFORNIA AND PARTLY CLOUDY SKIES OVER ARIZONA TODAY
PROVIDING A SLIGHT REPRIEVE FROM THE SCORCHING TEMPERATURES.
DESPITE THE HIGHER CLOUDS, HIGHS ARE STILL EXPECTED TO EASILY TOP
110 DEGREES ACROSS THE LOWER DESERTS TODAY, BUT THEY SHOULD BE A
FEW DEGREES COOLER THAN YESTERDAY'S.
IN THE LOWER LEVELS, A MODEST GULF SURGE OF MOISTURE IS CURRENTLY
WORKING ITS WAY INTO THE AREA WITH 65-70 DEGREE DEW POINTS ALREADY
INTO YUMA AND THE IMPERIAL VALLEY AND EVENTUALLY TO AROUND 60
DEGREES IN THE PHOENIX AREA LATER THIS MORNING. HOWEVER, EVEN WITH
SOME IMPROVEMENT IN MOISTURE FOR TODAY FORECAST SOUNDINGS SHOW
LITTLE SUPPORT FOR CONVECTION. LOW LEVEL MIXING RATIOS WILL AT
MOST REACH 8 G/KG THIS AFTERNOON WHICH IS BARELY ADEQUATE FOR EVEN
HIGH TERRAIN STORMS FOR AN IDEAL MONSOON SEASON DAY. THE
CONTINUED STRONG SUBSIDENCE FROM THE RIDGE OVERHEAD SHOULD BE
ENOUGH TO KEEP ANY POTENTIAL CONVECTION CONFINED TO HIGHER TERRAIN
AREAS THIS AFTERNOON/EARLY EVENING WITH AT MOST ISOLATED
COVERAGE. SLIGHTLY MORE FAVORABLE CONDITIONS SHOULD AT LEAST ALLOW
FOR SOME MORE SCATTERED CONVECTION OVER FAR SOUTHEAST ARIZONA
WHICH EVENTUALLY MAY BE ENOUGH TO KICK OFF A NORTHWARD PROGRESSING
OUTFLOW TOWARD PINAL AND MARICOPA COUNTIES LATE IN THE EVENING.
THE HRRR SUGGESTS A COMBINATION OF THIS POTENTIAL OUTFLOW WITH
SOME MID-LEVEL MOISTURE ADVECTION AND/OR GRAVITY WAVES FROM MORE
ORGANIZED CONVECTION OVER SONORA MAY BE ENOUGH TO SPARK OFF SOME
ELEVATED LATE EVENING SHOWERS AND WEAK STORMS. HAVE ADJUSTED POPS
UPWARD TO 10-20% OVER SOUTH-CENTRAL ARIZONA FROM 10 PM TO 3 AM
TONIGHT TO ACCOUNT FOR THIS POTENTIAL.
FRIDAY IS SHAPING UP TO BE RELATIVELY QUIET THROUGH THE MAJORITY
OF THE DAY WITH NO ADDITIONAL MOISTURE ADVECTION TONIGHT AND
THROUGH THE FIRST HALF OF FRIDAY. THE HIGHER LEVEL MOISTURE AND
CLOUDS FOR TODAY ARE ALSO EXPECTED TO PUSH OUT OF THE AREA
LEAVING MORE SUNSHINE FOR FRIDAY. CAMS SHOW LESS CONVECTIVE
ACTIVITY THAN TODAY, BUT THAT IS ONLY THROUGH FRIDAY AFTERNOON.
THE SUBTROPICAL HIGH IS ALSO FORECAST TO WEAKEN AND PUSH INTO
NORTHERN NEW MEXICO. GIVEN THE LOWERING HEIGHTS, BUT MORE
SUNSHINE FORECAST HIGHS ON FRIDAY ARE VERY SIMILAR TO TODAY'S,
KEEPING WIDESPREAD MAJOR TO EXTREME HEATRISK OVER THE AREA.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
A SIGNIFICANT PATTERN CHANGE IS SET TO BEGIN THIS WEEKEND WITH A
LARGE PACIFIC TROUGH SLOWLY MOVING SOUTHEASTWARD ACROSS THE
WESTERN U.S., EVENTUALLY PUSHING THE SUBTROPICAL HIGH INTO THE
SOUTHERN PLAINS BY SUNDAY. OUR MAIN FORECAST CONCERN WITH THIS
CHANGE WILL BE THE INCREASINGLY FAVORABLE CONDITIONS FOR
THUNDERSTORMS, ESPECIALLY BY SUNDAY AND MONDAY. THE INFLUENCE OF
THE TROUGH MAY OCCUR AS EARLY AS LATE FRIDAY NIGHT AND EARLY
SATURDAY AS A RELATIVELY STRONG JET STREAK MOVES THROUGH
CALIFORNIA INTO THE GREAT BASIN. THIS SHOULD RESULT IN INCREASING
UPPER LEVEL SUPPORT FOR SHOWERS AND THUNDERSTORMS, BUT WE WILL
ALSO HAVE TO HAVE ENOUGH MOISTURE. FOR NOW, GUIDANCE IS UNCLEAR ON
THE RAIN CHANCES FOR EARLY SATURDAY, BUT THE NBM IS TRYING TO PUT
A 30-40% CHANCE IN AFTER MIDNIGHT. THE DAYTIME HOURS SATURDAY ARE
JUST AS UNCLEAR AS MOISTURE IS LIKELY TO CONTINUE TO IMPROVE, BUT
WILL IT BE ENOUGH TO OVERCOME A MODEST CAPPING INVERSION.
GUIDANCE DOES SHOW POPS OF 30-40% DURING THE EVENING HOURS
SATURDAY FROM PHOENIX AND AREAS TO THE NORTH AND EAST OF PHOENIX,
BUT LITTLE CHANCE TO THE WEST. TEMPERATURES SATURDAY WILL COOL A
BIT FROM FRIDAY, BUT THERE SHOULD STILL BE ENOUGH RESIDUAL HEAT TO
PUSH DAYTIME HIGHS TO AROUND 110 DEGREES ACROSS THE WESTERN LOWER
DESERTS TO 107-109 DEGREES IN THE PHOENIX AREA.
SUNDAY INTO POSSIBLY MONDAY VERY WELL COULD BE QUITE ACTIVE AS
GUIDANCE IS POINTING AT VERY GOOD MOISTURE ADVECTION INTO ARIZONA,
SOMEWHAT DIRECTED BY A PASSING TROPICAL SYSTEM TO THE SOUTHWEST OF
SOUTHERN BAJA. ATMOSPHERIC PARAMETERS IMPROVE ON SUNDAY WITH
MUCAPES ANYWHERE FROM 1000-2000 J/KG AND LITTLE IF ANY CIN DURING
THE AFTERNOON HOURS. THE PRESENCE OF THE TROUGH OVER OR JUST TO
THE NORTHWEST OF OUR AREA SHOULD ALSO PROVIDE SOME MODEST SHEAR
AND UPPER LEVEL SUPPORT FOR STORM POTENTIAL ON SUNDAY AND/OR
MONDAY. DEPENDING ON THE EVOLUTION OF THE TROUGH, HEATING, AND
HOW MUCH MOISTURE GETS PULLED INTO OUR AREA, WE MAY NEED TO WORRY
ABOUT A STRONG TO SEVERE STORM POTENTIAL AS WELL AS A HEAVY
RAINFALL THREAT AS PWATS MAY REACH NEAR 1.75". DRIER AIR WILL ALSO
BE TRYING TO WORK INTO WESTERN PORTIONS OF OUR AREA BY SUNDAY,
LEAVING LITTLE CHANCE FOR RAIN OVER SOUTHEAST CALIFORNIA AND
POTENTIALLY SOUTHWEST ARIZONA. NBM POPS REFLECT THIS WITH AT MOST
10-20% CHANCES OVER THE WESTERN DESERTS, BUT POPS RISE TO 40-60%
FROM PHOENIX AND AREAS TO THE NORTH AND EAST OF PHOENIX ON SUNDAY.
THERE IS MUCH HIGHER MODEL UNCERTAINTY GOING INTO THE MID TO
LATTER HALF OF NEXT WEEK AS GEFS FAVORS MOISTURE STAYING MOSTLY IN
PLACE WHILE THE EPS FAVORS SOME MORE SIGNIFICANT DRYING. PART OF
THIS UNCERTAINTY IS DUE TO A HIGHLY ACTIVE TROPIC REGION TO OUR
SOUTHWEST WHICH VERY WELL COULD INFLUENCE OUR REGION AT TIMES.
TEMPERATURES ARE AT LEAST SLATED TO DROP A GOOD AMOUNT OVER THE
WEEKEND INTO EARLY NEXT WEEK WITH FORECAST HIGHS FALLING BACK TO
NEAR NORMAL ON SUNDAY AND THEN AT OR JUST BELOW THE NORMAL RANGE
EARLY NEXT WEEK. WE CAN'T EVEN RULE OUT HAVING HIGHS IN THE 90S
FOR A DAY ACROSS SOUTH-CENTRAL ARIZONA IF THE RAIN ACTIVITY IS
WIDESPREAD ENOUGH ON SUNDAY AND/OR MONDAY.
AVIATION
UPDATED AT 1814Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
NO SIGNIFICANT AVIATION WEATHER CONCERNS ARE ANTICIPATED UNDER
SCT-BKN MID/HIGH CLOUDS THROUGHOUT THE PERIOD. WINDS WILL MOSTLY
FOLLOW LIGHT, DIURNAL TENDENCIES WITH SPEEDS LESS THAN 10 KTS.
HOWEVER, GUSTY WINDS WILL BE POSSIBLE THIS EVENING AS A SOUTHERLY
OUTFLOW IS EXPECTED TO PUSH INTO THE VALLEY AROUND 03Z-06Z WITH
GUSTS AROUND 20-25 KTS. COULD SEE THIS OUTFLOW GENERATE SOME
BLOWING DUST THAT MAY RESULT IN REDUCED VISIBILITIES. HEADING INTO
THE OVERNIGHT HOURS, A FEW SHOWERS/ISOLATED STORM MAY DEVELOP
NEAR THE TERMINALS AND RESULT IN ERRATIC WIND DIRECTIONS AT TIMES.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION CONCERNS ARE EXPECTED THROUGH THE TAF PERIOD.
WINDS AT KIPL WILL FAVOR AN E/SE COMPONENT THROUGHOUT MUCH OF THE
PERIOD, WHILE WINDS AT KBLH FAVOR THE S TO SSW. SCT-BKN MID/HIGH
CLOUDS WILL PERSIST THROUGHOUT THE PERIOD.
FIRE WEATHER
HOT AND RELATIVELY DRY CONDITIONS WILL CONTINUE OVER THE NEXT
COUPLE OF DAYS WITH ONLY WIDELY ISOLATED SHOWERS AND THUNDERSTORMS
POSSIBLE. AFTERNOON MINIMUM HUMIDITIES WILL IMPROVE SLIGHTLY TO
15-20% THROUGH FRIDAY BEFORE IMPROVING FURTHER OVER THE WEEKEND AS
RAIN CHANCES INCREASE OVER ARIZONA. WINDS THROUGH FRIDAY WILL
OVERALL BE LIGHT AND FOLLOW DIURNAL TENDENCIES, WITH MODEST
AFTERNOON UPSLOPE/UPVALLEY BREEZINESS.
CLIMATE
RECORD HIGHS:
DATE PHOENIX YUMA EL CENTRO
---- ------- ---- ---------
AUG 27 114 IN 2023 120 IN 1981 117 IN 1981
AUG 28 117 IN 2023 118 IN 2023 117 IN 2009
AUG 29 116 IN 2023 117 IN 1954 117 IN 2005
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING UNTIL 8 PM MST SATURDAY FOR AZZ530>555-559-
560.
EXTREME HEAT WARNING UNTIL 8 PM MST FRIDAY FOR AZZ556-561-562.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT SATURDAY FOR CAZ562-565>567-
569-570.
EXTREME HEAT WARNING UNTIL 8 PM PDT FRIDAY FOR CAZ561-563-564-
568.
SHORT TERM...KUHLMAN
LONG TERM...KUHLMAN
AVIATION...SMITH
FIRE WEATHER...KUHLMAN
CLIMATE...18/KUHLMAN
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