127
FXUS65 KPSR 310829
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
129 AM MST THU JUL 31 2025
KEY MESSAGES
- HOT TEMPERATURES WILL CONTINUE TO BE A CONCERN THROUGH NEXT
WEEK WITH AT LEAST WIDESPREAD MODERATE HEATRISK EACH DAY.
- AREAS OF MAJOR HEATRISK ARE EXPECTED ACROSS SOUTH-CENTRAL
ARIZONA FRIDAY AND SATURDAY RESULTING IN AN EXTREME HEAT WARNING
FOR MARICOPA AND PINAL COUNTIES.
- OVERALL DRY CONDITIONS WILL PREVAIL FOR MUCH OF THE AREA WITH
VERY LIMITED CHANCES OF SHOWERS AND A FEW THUNDERSTORMS ACROSS
SOUTH-CENTRAL AND EASTERN ARIZONA TODAY INTO FRIDAY AND
POTENTIALLY AGAIN EARLY NEXT WEEK.
SHORT TERM /TODAY THROUGH FRIDAY/
LITTLE HAS CHANGED SINCE YESTERDAY WITH DRY AIR STILL STREAMING
INTO THE DESERT SOUTHWEST FROM OFF THE PACIFIC. THIS PERSISTENT
FETCH OF DRY AIR IS DUE TO FLOW AROUND THE STALLED OUT TROUGH
SITUATED OVER NORTHERN CALIFORNIA AND NEVADA. A TROUGH AXIS TO
OUR EAST IN NEW MEXICO ALSO HASN'T MOVED MUCH, BUT THE MOISTURE
ASSOCIATED WITH THE TROUGH HAS AT LEAST SHIFTED MORE INTO
SOUTHEASTERN ARIZONA. THE LIMITED MOISTURE IS STILL FORECAST TO
SEEP A BIT FURTHER WESTWARD, POTENTIALLY REACHING FAR SOUTH-
CENTRAL OR SOUTHWEST ARIZONA, BUT IT WILL BE VERY SHALLOW AND WILL
MOSTLY MIX OUT DURING THE AFTERNOON HOURS TODAY. THE MOISTURE MAY
BE ENOUGH FOR A FEW SCATTERED SHOWERS OR AN ISOLATED THUNDERSTORM
THIS AFTERNOON/EARLY EVENING ACROSS SOUTHERN MARICOPA INTO PINAL
COUNTY, BUT AS WITH THE PAST COUPLE OF DAYS THE BULK OF THE
CONVECTION WILL REMAIN OVER THE EASTERN ARIZONA HIGH TERRAIN. THE
HRRR IS ALSO STILL SHOWING SOME VERY LIMITED CHANCES FOR A FEW
SHOWERS OR A THUNDERSTORM DEVELOPING JUST AFTER MIDNIGHT INTO THE
PHOENIX AREA. WE HAVE ADDED 10% CHANCE POPS TO ACCOUNT FOR THIS
POTENTIAL.
ASIDE FROM THE LIMITED RAIN CHANCES, THE MAIN FORECAST CONCERN
WILL BE THE HOT TEMPERATURES AS THE SUBTROPICAL RIDGE RECENTERS
ITSELF OVER SOUTHERN ARIZONA BEGINNING FRIDAY. THIS WILL PUSH H5
HEIGHTS FROM 591-593DM CURRENTLY TO 595-597DM FOR FRIDAY INTO
SATURDAY AND PUSH DAYTIME HIGHS 2-4 DEGREES HIGHER. THE LATEST NBM
SHOWS HIGHS REACHING TO BETWEEN 110-114 DEGREES FOR FRIDAY AND
SATURDAY WITH OVERNIGHT LOWS AS WARM AS 90 DEGREES WITHIN THE
PHOENIX METRO. AREAS OF MAJOR HEATRISK ACROSS MARICOPA AND PINAL
COUNTIES HAS PROMPTED THE ISSUANCE OF AN EXTREME HEAT WARNING FOR
THE SOUTH-CENTRAL ARIZONA LOWER DESERTS FROM LATE FRIDAY MORNING
THROUGH EARLY SATURDAY EVENING.
LONG TERM /SATURDAY THROUGH THURSDAY/
THE REPOSITIONING AND THE STRENGTHENING OF THE SUBTROPICAL RIDGE
MEANS ANY MOISTURE WILL QUICKLY GET SCOURED OUT BY SATURDAY
DROPPING RAIN CHANCES TO BELOW 10% AREAWIDE. SURFACE DEW POINTS
ARE ALSO SHOWN DROPPING BRIEFLY INTO THE 20S AND 30S SATURDAY
BEFORE BEGINNING TO RECOVER STARTING SUNDAY. THE NEAR ZERO RAIN
CHANCES WILL CONTINUE TO PREVAIL INTO SUNDAY EVEN AS THE RIDGE
BEGINS TO WEAKEN AGAIN. TEMPERATURES ARE FORECAST TO DROP A FEW
DEGREES GOING INTO SUNDAY, PARTIALLY DUE TO THE WEAKENING RIDGE
AND ALSO BECAUSE OF THE MORE EFFICIENT OVERNIGHT COOLING FROM THE
DRY BOUNDARY LAYER CONDITIONS. HIGHS SUNDAY ARE STILL LIKELY TO
REACH 110 DEGREES FOR MANY LOWER DESERT LOCATIONS, BUT AS OF RIGHT
NOW NEARLY ALL OF THE AREA WILL FALL BELOW MAJOR HEATRISK.
GUIDANCE THEN SHOWS THE RIDGE SHIFTING A BIT FARTHER TO THE EAST
OVER SOUTHERN NEW MEXICO EARLY NEXT WEEK WITH H5 HEIGHTS BARELY
BUDGING ACROSS ARIZONA AND SOUTHERN CALIFORNIA. THIS EASTWARD
SHIFT MAY ALLOW FOR A RETURN OF SOME WEAK MOISTURE, BUT IT WOULD
LIKELY ONLY BE ENOUGH FOR SOME HIGH TERRAIN LOW END CONVECTION
FOR MONDAY AND TUESDAY.
ATTENTION THEN TURNS TOWARD A HEAVILY FAVORED SCENARIO OF ANOTHER
EXTREME HEAT EVENT BY THE MIDDLE OF NEXT WEEK. ENSEMBLES ALL AGREE
THE RIDGE WILL RESTRENGTHEN ONCE AGAIN STARTING TUESDAY, BUT WHILE
ALSO STAYING CENTERED OVER NEW MEXICO. THE H5 CENTER OF THE RIDGE
IS CURRENTLY FORECAST TO STRENGTHEN TO AROUND 600DM BY NEXT
WEDNESDAY OR THURSDAY REACHING RECORD OR NEAR RECORD HEIGHTS FOR
THE CLIMATOLOGICAL PERIOD. H5 HEIGHTS OF 598-600DM WILL BE
POSSIBLE THROUGH MUCH OF OUR AREA BY THE MIDDLE OF NEXT WEEK,
LIKELY BOOSTING OUR HIGHS TO BETWEEN 112-116 DEGREES. THE NBM IS
ALREADY FORECASTING LARGE AREAS OF MAJOR HEATRISK BEGINNING NEXT
WEDNESDAY WITH GUIDANCE SUGGESTING THIS NEXT HEAT EVENT WOULD
LAST AT LEAST 2-3 DAYS LATE NEXT WEEK. SOME MINOR RELIEF LOOKS TO
BE POSSIBLE BY THE FOLLOWING WEEKEND.
AVIATION
UPDATED AT 0530Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
THE PRIMARY WEATHER CONCERN WILL BE LOW CONFIDENCE ON THE WIND
FORECAST FOR THURSDAY EVENING DUE TO UNCERTAINTY IN EXACT LOCATION
AND STRENGTH OF THUNDERSTORMS THAT MAY DEVELOP TO THE
SOUTH/SOUTHEAST OF THE TERMINALS. A DECAYING OUTFLOW WILL SHIFT
WINDS OUT OF THE SOUTHEAST WITHIN THE NEXT HOUR OR SO. THOUGH THE
SHIFT WILL BE MORE ABRUPT THAN USUAL, SPEEDS ARE LIKELY TO BE AOB
12 KTS AND CONFIDENCE IS LOW THAT IT WILL REACH KSDL/KDVT.
THURSDAY, WINDS WILL SLOWLY VEER FROM SE TO SW DURING THE LATE
MORNING INTO THE AFTERNOON. EXPECT OCCASIONAL WESTERLY GUSTS INTO
THE UPPER TEENS ACROSS THE TERMINAL DURING THE MID-LATE AFTERNOON.
THUNDERSTORMS ARE ANTICIPATED TO FORM SOUTH AND EAST OF THE
TERMINALS THURSDAY AFTERNOON, CLOSER THAN PREVIOUS DAYS THIS WEEK.
THE PROXIMITY OF STORMS WILL MEAN THAT GUSTY OUTFLOW WINDS HAVE A
BETTER CHANCE OF REACHING THE TERMINALS, THOUGH THE EXACT
DIRECTION AND TIMING ARE QUITE UNCERTAIN AND HIGHLY DEPENDENT ON
WHERE STORM DEVELOPMENT IS MOST FOCUSED FORM AND THEIR STRENGTH.
AT THIS TIME, CONFIDENCE IS TOO LOW TO INCLUDE THE IMPACTS OF ANY
OUTFLOWS IN THE TAF.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
WINDS WILL FOLLOW A PATTERN NEARLY IDENTICAL TO THAT OF THE LAST
24 HOURS UNDER CLEAR SKIES. WINDS WILL BECOME VERY LIGHT AND VRB
OVERNIGHT AT KBLH, THEN SOUTH WINDS WILL PICK UP ONCE AGAIN AROUND
MIDDAY THURSDAY, DEVELOPING GUSTS INTO THE LOW 20S DURING THE
AFTERNOON. AT KIPL, WEST WINDS WILL LINGER THROUGH 10-12Z, THEN
BEGIN TO FAVOR SOUTHEAST THROUGH THURSDAY AFTERNOON. ANOTHER
PERIOD OF STRONGER WEST WINDS IS ANTICIPATED AT KIPL THURSDAY
EVENING.
FIRE WEATHER
THE LIMITED MONSOON MOISTURE WILL PROVIDE FOR ANOTHER DAY OF
MOSTLY HIGH TERRAIN SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
WITH DIMINISHING CHANCES ALREADY BY FRIDAY. CHANCES FOR WETTING
RAINS WILL REMAIN BELOW 10% RESULTING IN AT LEAST MINOR RISK OF
DRY LIGHTNING. AFTERNOON MINRHS TODAY AND FRIDAY WILL MOSTLY BE
BETWEEN 10-15% ACROSS THE LOWER DESERTS TO 15-20% IN HIGHER
TERRAIN AREAS BEFORE DROPPING FURTHER INTO THE WEEKEND. OUTSIDE
OF THE INFLUENCE OF THUNDERSTORMS, WINDS WILL GENERALLY FOLLOW
DIURNAL TENDENCIES WITH TYPICAL AFTERNOON UPSLOPE GUSTINESS.
TEMPERATURES WILL REMAIN ABOVE NORMAL WITH LOWER DESERT HIGHS
MOSTLY BETWEEN 108-113 DEGREES. DRY CONDITIONS WILL PREVAIL THIS
WEEKEND WITH NO RAIN CHANCES BEFORE VERY LIMITED MOSTLY HIGH
TERRAIN CHANCES RETURN EARLY NEXT WEEK.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING FROM 10 AM FRIDAY TO 8 PM MST SATURDAY FOR
AZZ534-537>544-546-548>555-559.
CA...NONE.
SHORT TERM...KUHLMAN
LONG TERM...KUHLMAN
AVIATION...WHITTOCK
FIRE WEATHER...KUHLMAN
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