816
FXUS65 KPSR 051701
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1000 AM MST WED AUG 5 2026
UPDATE
UPDATED AVIATION
KEY MESSAGES
- EXTREME HEAT CONDITIONS WILL PERSIST THROUGH THE WEEKEND WITH
TEMPERATURES HOVERING NEAR TO SEVERAL DEGREES ABOVE NORMAL WHILE
HUMIDITY VALUES REMAIN HIGHER THAN NORMAL.
- SHOWER AND THUNDERSTORM CHANCES WILL FAVOR EAST AND SOUTHEAST
ARIZONA THE REMAINDER OF THE WEEK WITH GUSTY OUTFLOW WINDS AND
BLOWING DUST THE MOST LIKELY IMPACTS FOR SOUTH-CENTRAL ARIZONA.
SHORT TERM /TODAY THROUGH THURSDAY/
HOT AND SOMEWHAT HUMID CONDITIONS WILL PREVAIL OVER THE NEXT COUPLE
OF DAYS AS THE HEAT DOME REMAINS IN PLACE OVER THE SOUTHWESTERN U.S.
THE CENTER OF THE SUBTROPICAL HIGH IS CURRENTLY LOCATED ACROSS
CENTRAL ARIZONA, LIKELY STAYING THERE THROUGH THURSDAY, WHILE ENOUGH
MOISTURE REMAINS TRAPPED UNDER THE HIGH TO CREATE DAILY CHANCES OF
HIGH TERRAIN SHOWER AND THUNDERSTORMS.
ALTHOUGH TEMPERATURES HAVE DROPPED OFF FROM THE 115+ DEGREE READINGS
FROM THIS PAST WEEKEND, THE HEAT DOME WILL CONTINUE TO BE ENOUGH TO
BRING UNCOMFORTABLY HOT CONDITIONS, ESPECIALLY WHEN CONSIDERING THE
INCREASED HUMIDITIES. THE INCREASED LOW LEVEL MOISTURE, PATCHES OF
CLOUDS, AND EVEN SUSPENDED DUST HELD BACK TEMPERATURES YESTERDAY. AS
OF 2 AM, MOST LOCALES ARE STILL HOLDING IN THE LOW TO MID 90S WITH
FORECAST LOWS MOSTLY IN THE MID 80S TO UPPER 80S. MORNING CLOUDS ARE
AGAIN EXPECTED TODAY WHICH WILL INITIALLY HOLD BACK TEMPERATURES,
BUT DECENT CLEARING IN THE AFTERNOON SHOULD STILL ALLOW TEMPERATURES
TO REACH NEAR 110 DEGREES FOR HIGHS. HIGH SURFACE DEW POINTS HOLDING
ABOVE 60 DEGREES ALL DAY TODAY WILL ALSO RESULT IN HEAT INDICES
BREACHING 110 DEGREES FOR THE BULK OF THE LOWER DESERTS.
CONVECTIVE POTENTIAL FOR THIS AFTERNOON AND EVENING REMAINS QUITE
UNCERTAIN, AT LEAST FOR THE SOUTH-CENTRAL ARIZONA LOWER DESERTS.
GUIDANCE CONTINUES TO POINT TOWARD A MORE ACTIVE STORM DAY TODAY
THAN YESTERDAY, AS LONG AS ENOUGH INSOLATION IS REALIZED THIS
AFTERNOON. THE 00Z HREF SHOWS STRONG INSTABILITY DEVELOPING THIS
AFTERNOON OVER THE REGION, WITH MUCAPE AS HIGH AS 1500-2000 J/KG
OVER GILA COUNTY THROUGH SOUTHEAST ARIZONA AND CIN ERODING
SUFFICIENTLY. CAMS SHOW STORMS FIRING MID AFTERNOON ALONG THE
MOGOLLON RIM SOUTHEASTWARD INTO SOUTHWEST NEW MEXICO AND THEN ACROSS
SOUTHEAST ARIZONA LATE AFTERNOON. A FEW STRONG TO POSSIBLY SEVERE
STORMS WILL BE POSSIBLE OVER THE HIGHER TERRAIN WITH WINDS BEING THE
MAIN THREAT. A MORE DEFINITIVE 5-10 KT EASTERLY STEERING FLOW TODAY
SHOULD AID IN PROGRESSING THE STORM ACTIVITY A BIT MORE QUICKLY WITH
SOME STORMS LIKELY APPROACHING THE LOWER DESERTS BETWEEN 01-03Z. THE
STORMS WILL HOWEVER ENCOUNTER LOWER INSTABILITY AND HIGHER CIN OVER
THE LOWER DESERTS, LIKELY CAUSING MOST OF THE ACTIVITY TO DISSIPATE.
STRONG OUTFLOW WINDS WITH AREAS OF DUST SEEMS LIKE AT LEAST A 50/50
CHANCE OF REACHING PINAL AND MARICOPA COUNTY THIS EVENING. THE
LATEST 06Z HRRR HAS ALSO INTRODUCED REDEVELOPING STORMS ALONG AN
ADVANCING OUTFLOW BOUNDARY, POTENTIALLY AFFECTING THE PHOENIX METRO
AND OTHER PARTS OF MARICOPA COUNTY THROUGH LATE EVENING. AS WITH THE
PAST COUPLE OF DAYS, THERE WILL BE PLENTY OF ELEVATED INSTABILITY
WITH HREF FORECAST MUCAPE OF 1000-1500 J/KG, BUT THE CONVECTIVE
INHIBITION WILL BE THE MAIN ISSUE. HAVE INCREASED POPS TO 10-20%
OVER THE SOUTH-CENTRAL ARIZONA LOWER DESERTS TO ACCOUNT FOR THE
HRRR'S OPTIMISM.
THE SUBTROPICAL HIGH IS FORECAST TO START STRENGTHENING AGAIN BY
THURSDAY WITH THE CENTER DRIFTING TO OVER NORTHERN ARIZONA AND
SOUTHERN UTAH. SLIGHTLY LESS CONVECTIVE POTENTIAL IS EXPECTED FOR
THURSDAY ACROSS THE EAST-CENTRAL ARIZONA HIGH TERRAIN AS SOME DRIER
AIR IS LIKELY TO MOVE IN FROM THE EAST. THIS SHOULD ALSO LEAD TO
LESS POTENTIAL OVER THE LOWER DESERTS.
LONG TERM /FRIDAY THROUGH TUESDAY/
STRENGTHENING OF THE RIDGE IS FORECAST THROUGH FRIDAY BEFORE
GRADUALLY WEAKENING THIS WEEKEND INTO MONDAY. GUIDANCE AGREES H5
HEIGHTS WILL RISE TO 596-598DM ON FRIDAY BEFORE DROPPING BACK TO 594-
596DM BY SUNDAY. THE STRENGTH OF THIS RIDGE WILL EASILY BE AROUND
THE 99TH PERCENTILE OF CLIMATOLOGY ACROSS THE REGION ON FRIDAY,
DROPPING BACK TO 90-97TH PERCENTILE ON SUNDAY. DUE TO THE STRENGTH
OF THE RIDGE AND SOME SLIGHT DRYING, TEMPERATURES ARE FORECAST TO
PEAK ON FRIDAY AND/OR SATURDAY WITH HIGHS 110-115 DEGREES. SURFACE
DEW POINTS SHOULD FALL BACK INTO THE UPPER 50S TO LOWER 60S DURING
THIS TIME, BUT IT WILL STILL FEEL SOMEWHAT HUMID AS HEAT INDICES
COULD REACH AS HIGH AS 115-120 DEGREES ACROSS THE LOWER DESERTS OF
SOUTHEAST CALIFORNIA. THERE WAS ENOUGH CONFIDENCE IN GUIDANCE TO
ALSO EXTEND THE EXTREME HEAT WARNING THROUGH SUNDAY AS THE
CONVECTIVE POTENTIAL SHOULD BE FAIRLY LIMITED. THE STRENGTH OF THE
HIGH AND SLIGHT DIP IN MOISTURE IS EXPECTED KEEP CIN VALUES QUITE
HIGH ACROSS THE AREA, ESPECIALLY OVER THE LOWER DESERTS. HIGHER
TERRAIN AREAS OF EASTERN ARIZONA WILL KEEP DAILY 15-30% CHANCE POPS,
WHILE THE PHOENIX AREA MOSTLY STAY BETWEEN 10-15%.
BY EARLY NEXT WEEK, MODELS SHOW THE RIDGE WEAKENING AGAIN, WHILE
MOST LIKELY STAYING CENTERED TO OUR NORTH. THIS SHOULD ALLOW FOR
BETTER MONSOON STORM CHANCES WITH MODELS LEANING TOWARD SOME
IMPROVING MOISTURE AND BETTER UPPER LEVEL SUPPORT. NBM/WPC POPS SEEM
TOO HIGH FOR SUNDAY AT 30-40% OVER CENTRAL AND EASTERN ARIZONA, BUT
THOSE CHANCES MAY BE MORE REASONABLE FOR MONDAY AND/OR TUESDAY OF
NEXT WEEK. TEMPERATURES WILL ALSO DRIFT LOWER EARLY NEXT WEEK DUE TO
THE WEAKENING OF THE RIDGE AND WITH MORE CONVECTIVE ACTIVITY IN THE
AREA. THE LATEST NBM SHOWS TEMPERATURES BACK INTO THE NORMAL RANGE
BY AROUND MONDAY OR TUESDAY.
AVIATION
UPDATED AT 1700Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
UNCERTAINTY IN STRONG, GUSTY OUTFLOW WINDS AND THE POTENTIAL FOR
SCATTERED TSRA THIS EVENING ARE THE MAIN FORECAST CHALLENGES.
CONFIDENCE IS VERY GOOD THAT WEST WINDS WILL PREVAIL THROUGH THE
AFTERNOON WITH THE POTENTIAL FOR SOME 15-20KT LATE AFTERNOON GUSTS.
TSRA SHOULD INITIALLY FORM WELL EAST AND SOUTH OF TERMINALS THIS
AFTERNOON WITH MULTIPLE OUTFLOW BOUNDARIES FOCUSED TOWARDS THE METRO
THIS EVENING. MODEL INDICATIONS SUGGEST AN INITIAL EASTERLY WIND
SHIFT FOLLOWED BY A SOUTHERLY OUTFLOW BOUNDARY. THIS SECONDARY
COLLISION MAY ALLOW SCATTERED TSRA TO DEVELOP MID EVENING WITH
ADDITIONAL ERRATIC WIND DIRECTIONS AND LOWERED VSBY DUE TO IMPORTED
BLDU. CONFIDENCE IN THIS OUTCOME IS ONLY LOW TO MODERATE WITH PROB30
APPROPRIATE FOR THIS SCENARIO.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR WEATHER ISSUES WILL EXIST THROUGH THURSDAY AFTERNOON UNDER
PERIODS OF MID/HIGH CLOUD DECKS. TRENDS IN WINDS WILL BE SIMILAR TO
THE PAST 24 HOURS WITH A PREFERENCE TOWARDS A SOUTHERLY DIRECTION
AND MODEST AFTERNOON/EARLY EVENING GUSTS.
FIRE WEATHER
HOT TEMPERATURES WILL CONTINUE ALL WEEK WITH FAIRLY ELEVATED
HUMIDITIES, BUT SHOWERS AND THUNDERSTORMS WILL MOSTLY REMAIN OVER
FAR EASTERN AND SOUTHEASTERN ARIZONA. GUSTY OUTFLOW WINDS ARE LIKELY
TO IMPACT THE SOUTH-CENTRAL ARIZONA LOWER DESERTS AGAIN TODAY WITH A
10% CHANCE OF STORMS. MINRHS WILL REMAIN ELEVATED AT 20-30% THROUGH
THURSDAY BEFORE DROPPING BACK INTO THE TEENS OVER THE LOWER DESERTS
FRIDAY INTO SATURDAY. OVERNIGHT RECOVERIES WILL REMAIN FAIR TO GOOD
AT 40-60%. OUTSIDE OF STORM OUTFLOWS, WINDS WILL MOSTLY FOLLOW
DIURNAL PATTERNS, WITH UPSLOPE AFTERNOON GUSTS OF 15-20 MPH AT TIMES.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING UNTIL 8 PM MST SUNDAY FOR AZZ530>544-546-
548>551-553>555-559.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT SUNDAY FOR CAZ560>570.
SHORT TERM...KUHLMAN
LONG TERM...KUHLMAN
AVIATION...18
FIRE WEATHER...KUHLMAN
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