429
FXUS65 KPSR 032121
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
221 PM MST MON AUG 3 2026
KEY MESSAGES
- EXTREME HEAT WILL PERSIST THROUGH THE END OF THE WORKWEEK WITH
INCREASING MOISTURE PUSHING HEAT INDICES TO AROUND 110 TO 115
DEGREES FOR THE LATTER HALF OF THE WEEK.
- SHOWER AND THUNDERSTORM CHANCES WILL FAVOR EASTERN AND
SOUTHEASTERN ARIZONA TODAY WITH A LOW CHANCE FOR A FEW ISOLATED
STORMS TO DEVELOP THIS EVENING ACROSS SOUTH-CENTRAL ARIZONA.
STRONG WINDS AND BLOWING DUST WILL BE THE PRIMARY CONCERNS.
- 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/
EXTREME HEAT CONTINUES ACROSS THE REGION AS A STRONG RIDGE OF HIGH
PRESSURE REMAINS IN PLACE. THIS MORNING, PHOENIX SKY HARBOR RECORDED
A LOW TEMPERATURE OF ONLY 97 DEGREES, WHICH TIES FOR THE ALL-TIME
RECORD WARM LOW FOR PHOENIX PROVIDED WE DON'T SEE TEMPERATURES COOL
BELOW THIS PRIOR TO MIDNIGHT TONIGHT. THE PERSISTENT STRONG RIDGE
WILL YIELD AFTERNOON HIGHS OF 112-116 DEGREES TODAY, RESULTING IN
FAIRLY WIDESPREAD MAJOR HEATRISK ACROSS THE REGION WITH EXTREME
HEATRISK FOCUSED ACROSS THE PHOENIX METRO AREA. THE WEAKENING TREND
OF THE RIDGE WILL ALLOW FOR AFTERNOON HIGH TEMPERATURES TO TREND
DOWNWARD OVER THE NEXT COUPLE OF DAYS. TEMPERATURES TUESDAY
AFTERNOON ARE FORECAST TO TOP OUT AROUND 108-113 DEGREES ACROSS THE
LOWER DESERTS AND WILL RESULT IN LOCALIZED AREAS OF MAJOR HEATRISK.
EXTREME HEAT WARNINGS REMAIN IN EFFECT TUESDAY FOR OUR ENTIRE AREA,
WITH THE EXCEPTION OF OUR HIGHER TERRAIN AREAS EAST OF PHOENIX, AND
HAVE NOW BEEN EXTENDED THROUGH FRIDAY EVENING (SEE LONG TERM
DISCUSSION FOR DETAILS).
MONSOONAL ACTIVITY ACROSS SOUTH-CENTRAL ARIZONA OVER THE NEXT COUPLE
OF DAYS IS EXPECTED TO REMAIN LIMITED, THOUGH THE FORECAST REMAINS
CONDITIONAL AND UNCERTAIN. AN ACTIVE DAY IS EXPECTED ACROSS
SOUTHEAST ARIZONA WHERE STRONG TO SEVERE THUNDERSTORMS ARE EXPECTED
TO DEVELOP THIS AFTERNOON IN AN ENVIRONMENT FAVORABLE FOR PRODUCING
STRONG OUTFLOWS. EAST-NORTHEASTERLY STEERING FLOW WILL KEEP MOST OF
THIS ACTIVITY CONFINED TO THE SOUTH OF OUR AREA, WHILE A FEW SHOWERS
AND STORMS MAY MOVE INTO FAR EASTERN GILA COUNTY THIS AFTERNOON.
DESPITE THE MONSOONAL ACTIVITY ACROSS SOUTHEAST ARIZONA REMAINING
FOCUSED SOUTH OF OUR AREA, CAMS CONTINUE TO SUPPORT STRONG
OUTFLOWS MOVING UP FROM THE SOUTH TOWARD THE VALLEY THIS EVENING.
GIVEN THIS, AREAS OF DENSE BLOWING DUST MAY OCCUR THIS EVENING,
PARTICULARLY ACROSS PINAL COUNTY. THE FORECAST THEN BECOMES MORE
CONDITIONAL AND UNCERTAIN IN REGARDS TO WHETHER OR NOT WE SEE NEW
THUNDERSTORM DEVELOPMENT OCCUR ACROSS SOUTH-CENTRAL ARIZONA. THE
HRRR REMAINS CONSISTENTLY OPTIMISTIC, SUGGESTING THE POTENTIAL FOR
COLLIDING OUTFLOWS OVER THE VALLEY THIS EVENING TO TRIGGER NEW
SHOWER AND THUNDERSTORM DEVELOPMENT. WHILE CAPE VALUES ARE
EXPECTED TO BE AROUND 1,000 J/KG, THERE WILL BE A FAIR AMOUNT OF
INHIBITION THAT WILL NEED TO BE OVERCOME, THUS YIELDING AN
UNCERTAIN FORECAST AROUND WHETHER OR NOT OUTFLOWS THIS EVENING
WILL BE ENOUGH TO PUNCH THROUGH THIS. WITH DCAPE VALUES IN EXCESS
OF 1,500 J/KG, ANY STORMS THAT WERE TO DEVELOP WOULD BE CAPABLE OF
PRODUCING STRONG WIND GUSTS.
THUNDERSTORM ACTIVITY TUESDAY WILL AGAIN BE FOCUSED ACROSS EASTERN
AND SOUTHEASTERN ARIZONA WITH EASTERLY STEERING FLOW KEEPING THIS
ACTIVITY FOCUSED SOUTH OF OUR AREA. A FEW ISOLATED SHOWERS AND
STORMS MAY PUSH INTO SOUTHERN GILA COUNTY TUESDAY AFTERNOON WITH
POPS CURRENTLY AROUND 20%. HI-RES GUIDANCE SUPPORT THUNDERSTORMS
ACROSS SOUTHEAST ARIZONA SENDING AN OUTFLOW NORTHWARD INTO OUR AREA,
WHICH COULD LEAD TO DENSE BLOWING DUST CONCERNS. HOWEVER, CHANCES
FOR NEW CONVECTIVE DEVELOPMENT INTO SOUTH-CENTRAL ARIZONA TUESDAY
EVENING IS LOW.
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.
AFTERNOON TEMPERATURES WEDNESDAY ARE FORECAST TO DROP INTO THE
107-111 DEGREE RANGE ACROSS THE LOWER DESERTS, RESULTING IN
VERY LOCALIZED COVERAGE OF MAJOR HEATRISK. HOWEVER, WE WILL SEE
INCREASING MOISTURE INTO THE REGION AS DEW POINTS SURGE INTO THE
60S TO AS HIGH AS THE LOWER/MID 70S ACROSS FAR SOUTHWEST ARIZONA
AND SOUTHEAST CALIFORNIA. THE INCREASED MOISTURE WILL LEAD TO HEAT
INDICES UPWARDS OF 110-115 DEGREES WITH HIGHER VALUES POSSIBLE
ACROSS PORTIONS OF SOUTHEAST CALIFORNIA. BEYOND WEDNESDAY, A
RESURGENCE OF THE RIDGE IS EXPECTED TO BEGIN TO RAISE TEMPERATURES
AGAIN WITH HIGHS DRIFTING 2-3 DEGREES HIGHER BY FRIDAY. GIVEN THE
RESTRENGTHENING OF THE RIDGE LATER THIS WEEK ALONG WITH HIGHER
HEAT INDICES EXPECTED THROUGH MUCH OF THE LATTER HALF OF THE
WEEK, THE EXTREME HEAT WARNING HAS BEEN EXTENDED THROUGH FRIDAY
EVENING FOR MOST OF THE AREA.
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 1715Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
A LOT OF UNCERTAINTY WITH THIS FORECAST FOR THIS EVENING,
ESPECIALLY WITH MAGNITUDE, DIRECTION AND TIMING OF WINDS WITH
THUNDERSTORM OUTFLOWS REACHING THE VALLEY. A COMPLEX OF STRONG
THUNDERSTORMS TO THE SOUTHEAST IS EXPECTED TO PUSH OUTFLOW WINDS
FROM THE SOUTH AND INTO THE VALLEY MID/LATE EVENING. THE FAVORED
TIMEFRAME LOOKS TO BE 03Z-06Z. 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 LOWER SLANTWISE VISIBILITY
AND REDUCE SURFACE VISIBILITY TO 5SM OR LESS. THERE IS ALSO A
CHANCE THAT THE VALLEY COULD SEE A FEW STORMS POP UP ALONG THE
OUTFLOW, BUT THESE CHANCES REMAIN LOW (5-10%). SHOULD THIS OCCUR,
ADDITIONAL OUTFLOWS WOULD BE ERRATIC AT THE TAF SITES.
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.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
GUSTY SOUTHERLY WINDS, PRIMARILY AT KBLH THIS 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 FAVOR EASTERN AND SOUTHEASTERN
ARIZONA OVER THE NEXT COUPLE OF DAYS, WHILE RAIN CHANCES REMAIN
LOWER ACROSS SOUTH-CENTRAL ARIZONA. STORMS ACROSS EASTERN AND
SOUTHEASTERN ARIZONA MAY SEND STRONG OUTFLOWS TOWARD THE PHOENIX
METRO AREA OVER THE NEXT COUPLE OF EVENINGS, WHICH COULD SPARK A
FEW ISOLATED SHOWERS AND STORMS. MIN RHS WILL CONTINUE TO IMPROVE,
CLIMBING TO AROUND 20-30% BY WEDNESDAY, WHILE OVERNIGHT
RECOVERIES RANGE BETWEEN 40-70%. 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 FRIDAY 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 FRIDAY FOR CAZ560>570.
SHORT TERM...SMITH
LONG TERM...SMITH/KUHLMAN
AVIATION...BENEDICT/FRIEDERS
FIRE WEATHER...SMITH/KUHLMAN
CLIMATE...18
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