868
FXUS65 KPSR 051029
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
329 AM MST WED AUG 5 2026
KEY MESSAGES
- THE EXTREME HEAT WARNING HAS BEEN EXTENDED THROUGH SUNDAY.
- 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 0900Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
THE MAIN AVIATION CONCERN WILL BE THE POTENTIAL FOR STRONG OUTFLOW
WINDS WEDNESDAY AFTERNOON/EVENING. DETAILS ABOUT THIS BOUNDARY
REMAIN UNCERTAIN AT THIS TIME, BUT AN INITIAL BEST GUESS HAS IT
ORIGINATING OUT OF THE EAST WITH GUSTS AROUND 25-30 KT, THOUGH
STRONGER GUSTS ARE NOT OUT OF THE QUESTION. IF A DUE EAST ORIGIN IS
FAVORED, DENSE BLOWING DUST WILL LIKELY BE LESS OF A CONCERN, BUT A
BRIEF WINDOW OF SUB-VFR CONDITIONS IN HAZE CANNOT BE RULED OUT.
THERE ARE SIGNS THAT POINT TOWARD VCSH/VCTS POPPING ALONG THIS
OUTFLOW, BUT CHANCES OF THAT REMAIN AT 15% OR LESS, SO ANY MENTION
OF RAIN OR THUNDERSTORMS HAS BEEN OMITTED FROM THE TAFS AT THIS
TIME. BOTTOM LINE IS, FORECAST CONFIDENCE FOR THIS WINDOW OF TIME IS
LOW AND MULTIPLE ADJUSTMENTS AND AMENDMENTS ARE LIKELY TO BE NEEDED.
IN THE MEAN TIME, WINDS APPEAR LIKELY TO FAVOR A WESTERLY COMPONENT
THROUGH THE REMAINDER OF THE MORNING, THOUGH SOME BRIEF PERIODS OF
VARIABILITY WOULD NOT BE SURPRISING. WESTERLY FLOW WILL CONTINUE
INTO THE AFTERNOON AND WILL BE ACCOMPANIED BY GUSTS AROUND 20 KT.
SCT TO SOMETIMES BKN MID-LEVEL CLOUDS WILL BE COMMON THROUGH MOST
OF THE FORECAST.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION CONCERNS ARE EXPECTED DURING THE NEXT 24 HOURS.
KIPL, WILL CONTINUE TO EXPERIENCE SOUTHEASTERLY FLOW WITH OCCASIONAL
GUSTS AND A BRIEF PERIOD OF VRB CONDITIONS LATE THIS MORNING. KBLH,
WILL SEE GENERALLY SOUTHERLY WINDS WITH GUSTS CLOSE TO 25 KT
DEVELOPING BY LATE MORNING. FEW TO SOMETIMES SCT MID AND HIGH LEVEL
CLOUDS WILL BE PRESENT OVER THE REGION THROUGH THE TAF PERIOD.
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...RW
FIRE WEATHER...KUHLMAN
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