969
FXUS65 KPSR 031003
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
303 AM MST MON AUG 3 2026
KEY MESSAGES
- EXTREME HEAT WILL PERSIST FOR AT LEAST THE FIRST PART OF THE
WEEK WITH HIGH TEMPERATURES TOPPING OUT IN THE 110 TO 116
DEGREE RANGE OVER MUCH OF THE LOWER DESERTS.
- SHOWER AND THUNDERSTORM CHANCES WILL INCREASE AT LEAST ACROSS
EASTERN ARIZONA TODAY WITH GUSTY WINDS AND BLOWING DUST A BETTER
POSSIBILITY INTO THE SOUTH-CENTRAL ARIZONA LOWER DESERTS THIS
EVENING.
- DAY TO DAY MOSTLY EASTERN ARIZONA HIGH TERRAIN STORM CHANCES ARE
EXPECTED THROUGH THE REST OF THE WEEK WITH HOT AND HUMID
CONDITIONS PERSISTING.
SHORT TERM /TODAY THROUGH TUESDAY/
A CONDITIONAL AND UNCERTAIN FORECAST IS PRESENTING ITSELF FOR
TODAY INTO TONIGHT AS MOISTURE CONTINUES TO INCREASE ACROSS
SOUTHERN ARIZONA AND INSTABILITY IMPROVES. THE STRONG HIGH
PRESSURE RIDGE REMAINS IN PLACE ACROSS THE SOUTHWESTERN U.S., BUT
IT WILL CONTINUE TO WEAKEN OVER THE NEXT 24 HOURS. THE HEAT DOME
IS STILL IN PLACE WHICH WILL CONTINUE TO BRING AREAS OF MAJOR TO
EXTREME HEATRISK THROUGH AT LEAST TUESDAY, BUT IT WILL ALSO HELP
TO PRODUCE STEEP MID-LEVEL LAPSE RATES AND MODESTLY HIGH ELEVATED
CAPE OF AROUND 1000 J/KG TODAY AND POTENTIALLY EVEN HIGHER CAPE
TUESDAY. EXTREME HEAT WARNINGS REMAIN IN EFFECT THROUGH TUESDAY
WITH HIGHS LOWERING SLIGHTLY, BUT STILL STAYING ABOVE 110 DEGREES,
WHILE INCREASING HUMIDITIES HELP TO KEEP AFTERNOON HEAT INDICES
BETWEEN 110-115 DEGREES.
CONVECTIVE POTENTIAL TODAY IS A CHALLENGING FORECAST AS MANY
FACTORS WILL COME INTO PLAY. LOW AND MID LEVEL MOISTURE HAS BEEN
LACKING OVER THE PAST SEVERAL DAYS, BUT THAT IS NOW CHANGING AS
INCREASING SOUTHERLY FLOW IN THE LOW LEVELS WILL PULL DECENT
MOISTURE NORTHWARD INTO SOUTHEAST CALIFORNIA AND SOUTHERN ARIZONA
OVER THE NEXT 48 HOURS. SURFACE DEW POINTS HAVE BEEN GRADUALLY
IMPROVING SINCE SATURDAY WITH MID TO UPPER 50S NOW ACROSS MUCH OF
THE AREA TO AS HIGH AS THE UPPER 60S TO LOWER 70S IN YUMA. STEADY
MOISTURE ADVECTION IS FORECAST, KEEPING DEW POINTS MOSTLY IN THE
MID 50S TO AROUND 60 EVEN THROUGH THIS AFTERNOON.
THE DECREASING INFLUENCE OF THE HIGH WILL LESSEN SUBSIDENCE A BIT
TODAY, WHILE THE INCREASING MOISTURE WILL IMPROVE INSTABILITY.
00Z CAMS SHOWED SCATTERED STORM COVERAGE FORMING OVER THE WHITE
MTNS AND EVEN MORE SO ACROSS SOUTHEAST ARIZONA, TRACKING
SOUTHEASTWARD LATE THIS AFTERNOON AND EVENING. HOWEVER, A STRONG
CAPPING INVERSION IS STILL EXPECTED ACROSS THE LOWER DESERTS,
LIKELY PROHIBITING CONVECTION TO FORM. THE MAIN THREATS FOR TODAY
SHOULD BE STRONG GUSTY WINDS AND BLOWING DUST AS MOISTURE WILL
STILL BE FAIRLY MARGINAL AND THE FLOW ALOFT IS VERY WEAK. A STORM
OR TWO COULD STILL END UP BECOMING ANCHORED TO A HIGH TERRAIN
FEATURE LEADING TO LOCALIZED HEAVY RAINFALL, BUT THE THREAT FOR
ANY FLOODING IS STILL QUITE LOW. CAMS ALSO MOSTLY AGREE ON A
DECENT NORTHWARD PROPAGATING OUTFLOW MOVING INTO PINAL AND
MARICOPA COUNTIES THIS EVENING POTENTIALLY BRINGING 35+ MPH WINDS
AND BLOWING DUST.
THE 06Z THAT CAME OUT JUST AFTER MIDNIGHT HAS NOW INTRODUCED SOME
SHOWERS AND STORMS DEVELOPING OVER THE HIGH TERRAIN JUST TO THE
NORTHEAST OF PHOENIX MID TO LATE EVENING BEFORE PROGRESSING
THROUGH PHOENIX. THERE HAD BEEN HINTS OF THIS POTENTIAL WITHIN THE
00Z RUNS, BUT THE CAMS ONLY SHOWED WEAK SHOWERS. THIS STORM
POTENTIAL WILL BE VERY CONDITIONAL AND OF LOW PROBABILITY (10%)
AS IT WILL BE DIFFICULT TO GET THROUGH A RATHER STRONG CAP. IT
LOOKS LIKE THE HRRR IS TRYING TO PICK UP ON A LITTLE BATCH OF
SHOWERS AND WEAK STORMS DRIFTING SOUTH SOUTHWESTWARD ACROSS
NORTHERN GILA COUNTY BEFORE POTENTIALLY INTERACTING WITH THE
EXPECTED NORTHWARD PROGRESSING OUTFLOW MID EVENING. IT IS POSSIBLE
COLLIDING OUTFLOWS MAY BE ENOUGH TO TAP INTO THE ELEVATED CAPE
OVER THE LOWER DESERTS TO SPAWN SOME ADDITIONAL STORMS NEAR OR
EVEN OVER PHOENIX LATE THIS EVENING. WE HAVE INTRODUCED A SLIGHT
CHANCE FOR THIS POTENTIAL FROM AROUND 9 PM THROUGH JUST AFTER
MIDNIGHT TONIGHT.
TUESDAY'S FORECAST IS ALSO QUITE CONDITIONAL AS IT WILL LARGELY
DEPEND ON WHAT HAPPENS THIS EVENING. IF STORMS END UP BEING QUITE
EXTENSIVE TODAY, IT SHOULD COOL THINGS OFF SOME OR EVEN SLIGHTLY
OVERTURN THE ATMOSPHERE TO DECREASE INSTABILITY. RIGHT NOW, THIS
SCENARIO PROBABLY HAS A 20% CHANCE OF OCCURRING. OF HIGHER
LIKELIHOOD IS A MORE MODEST STORM COVERAGE TODAY, MAINLY AFFECTING
HIGHER TERRAIN AREAS. THIS WOULD NOT AFFECT INSTABILITY FOR
TUESDAY MUCH LEADING TO ANOTHER DECENT CHANCE OF SHOWERS AND
STORMS ACROSS EAST-CENTRAL AND SOUTHEASTERN ARIZONA TUESDAY
AFTERNOON/EVENING. IN FACT, THE 00Z HREF SHOWS EVEN HIGHER
INSTABILITY FOR TUESDAY AS MOISTURE CONTINUES TO INCREASE WITH
SIMILAR LEVELS OF CONVECTIVE INHIBITION. CAMS FOR TUESDAY SHOW
DECENT STORM COVERAGE FROM THE WHITE MTNS SOUTHWARD THROUGH FAR
SOUTHEAST ARIZONA WITH ANOTHER POTENTIAL OUTFLOW PROGRESSING INTO
THE LOWER DESERTS IN THE EVENING. HOWEVER, THE CHANCES FOR ANY
FURTHER DEVELOPMENT INTO THE LOWER DESERTS SEEMS LOWER THAN TODAY.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
HOT AND HUMID (AT LEAST FOR THIS REGION) CONDITIONS ARE FORECAST
FOR THE LATTER HALF OF THE WEEK AS THE SUBTROPICAL RIDGE WILL
STRENGTHEN ONCE AGAIN WITH PEAK H5 HEIGHTS LIKELY REACHING
597-599DM OVER NORTHERN ARIZONA, SOUTHERN NEVADA, AND SOUTHERN
UTAH. THE STRENGTH LOOKS TO BE JUST SHY OF WHAT JUST OCCURRED THIS
PAST WEEKEND, BUT GUIDANCE SHOWS THE RIDGE CENTER TO OUR NORTH
INSTEAD OF DIRECTLY OVER CENTRAL ARIZONA.
THE CURRENT EXTREME HEAT WARNING GOES THROUGH TUESDAY WITH THE
HEATRISK DECREASING TO VERY LOCALIZED MAJOR ON WEDNESDAY.
HOWEVER, THIS DECREASE IN HEATRISK IS LARGELY DUE TO THE INCREASE
IN MOISTURE AS FORECAST HEAT INDICES REALLY DO NOT GO DOWN.
FORECAST HIGHS WEDNESDAY RANGE FROM 107-110 DEGREES IN PHOENIX TO
108-111 DEGREES ACROSS THE WESTERN LOWER DESERTS, HOWEVER HEAT
INDICES SHOULD STAY BETWEEN 110-115 DEGREES AS DEW POINTS SURGE
INTO THE 60S TO AS HIGH AS THE LOWER 70S ACROSS FAR SOUTHWEST
ARIZONA AND SOUTHEAST CALIFORNIA. BEYOND WEDNESDAY, A RESURGENCE
OF THE RIDGE IS EXPECTED TO BEGIN TO RAISE TEMPERATURES AGAIN WITH
HIGHS DRIFTING A DEGREE OR TWO HIGHER BY FRIDAY. UNLESS THINGS
CHANGE, IT SEEMS LIKELY THE EXTREME HEAT WARNING WILL BE EXTENDED
FOR A GOOD PORTION OF THE AREA THROUGH THE REST OF THE WEEK.
HOWEVER, ANY BIGGER CONVECTIVE DAY COULD DISRUPT THE ATMOSPHERE
LEADING TO A SLIGHTLY COOLER DAY.
MONSOON STORM POTENTIAL FOR THE REST OF THE WEEK LOOKS TO BE
FAIRLY LOW TO AT MOST MID GRADE WITH 20-40% CHANCES MOST DAYS OVER
THE EASTERN ARIZONA HIGH TERRAIN TO 10-20% INTO THE ARIZONA LOWER
DESERTS. THERE ARE SOME HINTS AT A POTENTIAL INCREASE IN
CONVECTIVE ACTIVITY MAYBE BY THE WEEKEND INTO EARLY NEXT WEEK, BUT
WE DO NOT PUT MUCH FAITH IN THE LONG RANGE MODELS FOR MONSOON
ACTIVITY. ALTHOUGH, AS LONG AS THE HIGH CENTER ENDS UP STAYING
POSITIONED FAR ENOUGH TO OUR NORTH, IT AT LEAST SEEMS QUITE
PLAUSIBLE ANY MINOR EASTERLY WAVE COULD MARCH ON THROUGH
PROVIDING ENHANCED CHANCES AT SOME POINT.
AVIATION
UPDATED AT 0800Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
THE PRIMARY AVIATION WEATHER CONCERN AND POTENTIAL IMPACT WILL BE
STRONG THUNDERSTORM OUTFLOW WINDS MOVING THROUGH THE PHOENIX AREA
LATE THIS EVENING FROM THE SOUTH. THERE IS MODERATE TO HIGH
CONFIDENCE THAT AN OUTFLOW WILL MOVE THROUGH, CURRENTLY FAVORED
BETWEEN 03-06Z, BUT THERE IS SOME UNCERTAINTY ON HOW STRONG WINDS
WILL BE. THERE IS MODEL SUPPORT FOR GUSTS AS HIGH AS 35-40 KTS AND
WINDS OF THIS MAGNITUDE MAY ALSO BRING A WALL OF DUST INTO THE AREA,
ENOUGH TO REDUCE VISIBILITY TO 5SM OR LESS. STORMS ARE EXPECTED TO
STAY WELL EAST AND SOUTH OF THE AREA, BUT THERE IS STILL A 5-10%
SOMETHING POPS UP OR DRIFTS INTO THE METRO.
PRIOR TO THE OUTFLOW, WINDS WILL CONTINUE TO FOLLOW TYPICAL DIURNAL
TENDENCIES, WITH SOME GUSTY (20-25 KT) WESTERLY WINDS THIS
AFTERNOON. THERE IS SOME UNCERTAINTY WITH WIND DIRECTIONS LATER
TONIGHT, FOLLOWING THE OUTFLOW, BUT EASTERLY WINDS GENERALLY FAVORED
TO DEVELOP BEFORE DAWN TUESDAY. MID AND HIGH CLOUDS WILL BE COMMON
THROUGH THE TAF PERIOD, WITH BASES DROPPING DOWN TO AROUND 10K FT
AGL MONDAY EVENING.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
GUSTY SOUTHERLY WINDS, PRIMARILY AT KBLH MONDAY AFTERNOON AND
EVENING, WILL BE THE MAIN AVIATION WEATHER ISSUE THROUGHOUT THE
TAF PERIOD UNDER MOSTLY CLEAR SKIES. AT KIPL, WINDS WILL GENERALLY
BE OUT OF THE SOUTHEAST, WITH AN INCREASE IN SPEEDS BETWEEN THE
SOUTH AND SOUTH-SOUTHWEST. OVERALL WIND SPEEDS WILL FLUCTUATE
BETWEEN 8-13 KTS, WITH GUSTS NEAR 20-25 KTS IN THE AFTERNOON AT
KBLH THAT INCREASE FURTHER IN THE EVENING UPWARDS OF 25-30 KTS.
LOCALIZED DUST STREAMERS AND WIDESPREAD LOFTED DUST MAY BE
GENERATED BY THE WINDS MONDAY NIGHT, WHICH COULD IMPACT SLANTWISE
VISIBILITY.
FIRE WEATHER
HOT TEMPERATURES WILL CONTINUE ALL WEEK, BUT WITH INCREASING LOW
LEVEL MOISTURE AND IMPROVING HUMIDITIES OVER THE NEXT COUPLE OF
DAYS. SHOWER AND STORM POTENTIAL WILL BE QUITE GOOD ACROSS FAR
SOUTHEAST ARIZONA TODAY, WHILE THE ACTIVITY IS LIKELY TO STAY
MOSTLY EAST AND SOUTHEAST OF GLOBE. GUSTY SOUTHERLY OUTFLOW WINDS
ARE LIKELY THIS EVENING ACROSS SOUTH-CENTRAL ARIZONA AND
POTENTIALLY AGAIN ON TUESDAY. MINRHS WILL IMPROVE TO 15-20% TODAY
AND 20-25% ON TUESDAY WITH OVERNIGHT RECOVERIES BETWEEN 40-60%.
OUTSIDE OF STORM OUTFLOWS, WINDS WILL MOSTLY FOLLOW DIURNAL
PATTERNS, BUT WEST SOUTHWESTERLY WINDS WILL BE DOMINANT MUCH OF
THE TIME WITH AFTERNOON GUSTS OF 15-25 MPH AT TIMES. SIMILAR LOW-
GRADE MONSOON STORM CONDITIONS ARE EXPECTED THROUGH THE REST OF
THE WEEK WITH HUMIDITIES STAYING FAIRLY ELEVATED AND TEMPERATURES
ABOVE NORMAL.
CLIMATE
RECORD HIGH TEMPERATURES:
DATE PHOENIX YUMA EL CENTRO
---- ------- ---- ---------
AUG 3 116 IN 2024 116 IN 1998 117 IN 2021
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING UNTIL 8 PM MST TUESDAY FOR AZZ530>544-546-
548>551-553>555-559.
EXTREME HEAT WARNING UNTIL 8 PM MST THIS EVENING FOR AZZ545-547-
552-556>558-560>563.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT TUESDAY FOR CAZ562-563-
565>567-569-570.
EXTREME HEAT WARNING UNTIL 8 PM PDT THIS EVENING FOR CAZ560-561-
564-568.
SHORT TERM...KUHLMAN
LONG TERM...KUHLMAN
AVIATION...BENEDICT
FIRE WEATHER...KUHLMAN
CLIMATE...18
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