572
FXUS65 KPSR 240810
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
110 AM MST FRI JUL 24 2026
KEY MESSAGES
- MUCH ABOVE NORMAL TEMPERATURES WILL CONTINUE THROUGH THE WEEKEND
WITH READINGS APPROACHING NEAR RECORD LEVELS AND EXTREME HEAT
WARNINGS IN EFFECT.
- THE HIGH PRESSURE SYSTEM RESPONSIBLE FOR THE EXTREME HEAT WILL
ALSO RESTRICT THUNDERSTORM DEVELOPMENT WITH MINIMAL CHANCES TODAY.
- TEMPERATURES WILL COOL SLIGHTLY EARLY NEXT WEEK AS INCREASED
THUNDERSTORM COVERAGE RETURNS TO THE REGION.
SHORT TERM /TODAY THROUGH SUNDAY/
A SPRAWLING SUBTROPICAL HIGH PRESSURE SYSTEM WAS COVERING THE
SOUTHERN CONUS EARLY THIS MORNING WITH ONE 597DM H5 CENTER OVER
SOUTHERN NEW MEXICO. THE OVERALL TREND IN THE ANTI-CYCLONE CENTER IS
TOWARDS A RETROGRESSIVE PHASE, HOWEVER THIS WILL CHANGE OVER THE
NEXT 48 HOURS WITH THE CORE LIFTING TOWARDS CENTRAL COLORADO.
DESPITE THIS MOVEMENT, THE FORECAST AREA WILL MAINTAIN H5 HEIGHTS IN
A 596-598DM RANGE WITH H8 AND H7 TEMPERATURES WELL ABOVE +30C AND
+15C RESPECTIVELY WHICH ARE GENERAL PROXIES FOR LOWER ELEVATION
TEMPERATURES REACHING/EXCEEDING 110F. NUMERICAL GUIDANCE SPREAD HAS
NARROWED RECENTLY PROVIDING INCREASED CONFIDENCE OF MANY LOWER
ELEVATION COMMUNITIES TOUCHING 115F TODAY AND SATURDAY YIELDING
WIDESPREAD MAJOR AND AREAS OF EXTREME HEATRISK. CONFIDENCE IN
FORECAST TEMPERATURES DETERIORATES SIGNIFICANTLY SUNDAY AS STRONG,
MOIST THUNDERSTORM OUTFLOWS SATURDAY NIGHT MAY SUBSTANTIALLY ALTER
BOUNDARY LAYER MOISTURE AND MIXING DEPTHS, AS WELL AS INTRODUCING
PESKY MIDLEVEL CLOUD DECKS DETRIMENTAL TO DAYTIME INSOLATION. THIS
OUTCOME IS REFLECTED IN NUMERICAL GUIDANCE WHERE THE FULL RANGE IN
ENSEMBLE SPREAD WIDENS, BUT ALSO ABRUPTLY DROPS FROM THE
FRIDAY/SATURDAY LEVELS.
AS THE CENTER OF THE SUBTROPICAL RIDGE SHIFTS INTO COLORADO, THIS
WILL ALLOW BETTER EASTERLY FLOW TO DEVELOP ON THE SOUTHERN PERIPHERY
OF THE ANTI-CYCLONE OVER NORTHERN MEXICO/SOUTHERN ARIZONA.
SUBSIDENCE AND SOMEWHAT DRIER AIR WILL BE MAINTAINED TODAY OVER THE
CWA IN PROXIMITY TO THE HIGH PRESSURE CENTER. HOWEVER MUCH LIKE
YESTERDAY, THIS WILL NOT COMPLETELY PRECLUDE DEEP CONVECTIVE
DEVELOPMENT OVER THE MOST FAVORED MOUNTAIN LOCATIONS, THOUGH THIS
ACTIVITY SHOULD BE VERY ISOLATED AND SHORT-LIVED IN NATURE. THIS
WILL GRADUALLY CHANGE OVER THE WEEKEND AS A WELL DEFINED EASTERLY
WAVE/INVERTED TROUGH COMPRISED OF TROPICAL REMNANTS CROSSES INTO
NORTHERN MEXICO.
CONFIDENCE IS GROWING THAT THE NORTHERN EXTENT OF THE INVERTED
TROUGH AND JET STREAK WILL CROSS INTO SOUTHERN ARIZONA SATURDAY
AFTERNOON PROVIDING A VERY CONVECTIVELY FAVORABLE DIFLUENT FLOW
ALOFT. WHILE MIXING RATIOS LANGUISHING UNDER 10 G/KG AND A WARM
MIDLEVEL THERMAL LAYER SHOULD PRECLUDE STORM DEVELOPMENT OVER MOST
LOWER ELEVATION LOCATIONS, DCAPE VALUES 1500-2000 J/KG WILL PROMOTE
STRONG, LONG LIVED OUTFLOW BOUNDARIES RACING INTO LOWER DESERTS
CREATING ELEVATED CHANCES OF DENSE BLOWING DUST (PRIMARILY OVER
PINAL COUNTY). THIS OUTFLOW WILL ALSO ENHANCE AND DEEPEN THE
MOISTURE POOL BRINGING BOUNDARY LAYER MIXING RATIOS BACK INTO A 11-
12 G/KG RANGE AND SPIKING TOTAL COLUMN PWATS NEAR 1.75".
SURPRISINGLY, MODELS ARE NOT OVERLY ENTHUSIASTIC REGARDING MORE
EXPANSIVE THUNDERSTORM DEVELOPMENT SUNDAY WITH A CONTINUATION OF A
FAVORABLE SYNOPTIC PATTERN, MLCAPE EXCEEDING 1000 J/KG, AND DCAPE
STILL NEAR 1500 J/KG. FORECAST BUFR SOUNDINGS SUGGEST LOWER
ELEVATION CINH IN EXCESS OF 25 J/KG, THOUGH MULTIPLE COLLIDING
OUTFLOWS SHOULD CONCEIVABLY BREACH THIS INHIBITION SUGGESTING THERE
MAY BE OTHER FACTORS CONTRIBUTING TO MODELS NOT PRODUCING BETTER
STORM CHANCES.
LONG TERM /MONDAY THROUGH THURSDAY/
STRONG, EXPANSIVE RIDGING WILL REMAIN NEARLY IN PLACE NEXT WEEK
ACROSS THE SOUTHWEST AND CENTRAL UNITED STATES WITH THE ANTI-CYCLONE
CENTER ROTATING BACK FROM CENTRAL COLORADO INTO NEW MEXICO AND
ARIZONA. EARLY IN THE WEEK, SUFFICIENT EASTERLY FLOW WILL PREVAIL
OVER THE REGION JUXTAPOSED WITH MARGINALLY SUPPORTIVE MIXING RATIOS
OF 9-11 G/KG FOR SCATTERED STORMS. THERE REMAINS CONSIDERABLE
UNCERTAINTY REGARDING A MORE PREFERRED TIME FRAME FOR HIGHER POPS IN
ANY GIVEN LOCATION WITH MESOSCALE DETAILS LIKELY BECOMING MORE
IMPORTANT TOWARDS CONVECTIVE EVOLUTION. UNFORTUNATELY, THE MANDATED
NBM/WPC FORECAST DURING THIS TIME ONLY FURTHER COMPLICATES AND
DIMINISHES THE FORECAST CONFIDENCE WITH NUMEROUS INSTANCES OF
SPURIOUS QPF FORCING PROCEDURAL, UN-SCIENTIFIC HIGHER POPS SPREAD
OVER UNCOMMON TIME PERIODS BASED ON CLIMATOLOGY AND THE
PREPONDERANCE OF TRUSTED MODEL OUTPUT. IN REALITY, THIS APPEARS TO
BE A VERY TYPICAL MONSOON PATTERN WITH ALTERNATING CONVECTIVELY
ACTIVE AND INACTIVE DAYS. BY THE LATTER HALF OF THE WEEK, THERE ARE
A HANDFUL OF NAEFS MEMBERS INDICATING NOTABLE STRENGTHENING OF THE
HIGH PRESSURE WITH 600DM H5 HEIGHTS MATERIALIZING OVER NORTHERN
AZ/SOUTHERN UT. IT APPEARS THE NBM/WPC FORECASTS ARE LATCHING ONTO
THIS SCENARIO AS POPS DWINDLE TO MUCH LOWER THAN EXPECTED VALUES
GIVEN THE ENSEMBLE MEAN SYNOPTIC PATTERN. THE LARGER IMPACT OF THIS
OUTCOME WOULD BE A RETURN TO MAJOR HEATRISK AND EXTREME HEAT
THRESHOLDS TOWARDS THE END OF THE WEEK.
AVIATION
UPDATED AT 0450Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
NO MAJOR AVIATION WEATHER CONCERNS UNDER FEW MID TO HIGH LEVEL CLOUD
DECKS ARE EXPECTED THROUGHOUT THE TAF PERIOD. THE OVERALL WIND
PATTERN WILL CONTINUE TO EXHIBIT THE TYPICAL DIURNAL TENDENCIES WITH
SPEEDS GENERALLY AOB 10 KTS, ALTHOUGH SOME OCCASIONAL AFTERNOON
GUSTS IN THE MID TO UPPER TEENS WILL BE POSSIBLE FRIDAY.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION WEATHER CONCERNS UNDER FEW MID TO HIGH LEVEL CLOUD
DECKS ARE EXPECTED THROUGHOUT THE TAF PERIOD. WIND DIRECTIONS WILL
GENERALLY FLUCTUATE BETWEEN THE SOUTHEAST TO SOUTHWEST. SOME
ELEVATED GUSTS UPWARDS OF 20-25 KTS ARE LIKELY FRIDAY AFTERNOON AT
KBLH.
FIRE WEATHER
THUNDERSTORM CHANCES WILL REMAIN LOW TODAY WITH ONLY A LIMITED
OPPORTUNITY REMAINING OVER HIGH TERRAIN AREAS IN ARIZONA. BETTER
CHANCES FOR MORE EXPANSIVE STORM COVERAGE AND WETTING RAINFALL WILL
ARRIVE LATER IN THE WEEKEND AND EARLY NEXT WEEK WITH ACTIVITY
FOCUSED OVER HIGHER TERRAIN LOCATIONS. WITH TEMPERATURES HOVERING
MUCH ABOVE NORMAL AND NEAR RECORD LEVELS THE NEXT SEVERAL DAYS,
MINIMUM AFTERNOON HUMIDITY IN A 10-25% RANGE WILL IMPROVING CLOSER
TO A 20-30% RANGE NEXT WEEK. CORRESPONDINGLY, OVERNIGHT RECOVERY
WILL MOSTLY BE IN A FAIR TO GOOD RANGE OF 30-60% WITH SOMEWHAT
HIGHER VALUES NEXT WEEK. OUTSIDE OF THUNDERSTORM OUTFLOWS, WIND
SPEEDS SHOULD BE FAIRLY LIGHT THROUGH THE PERIOD WITH ONLY LOCAL
AFTERNOON GUSTS 20-25 MPH.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING UNTIL 8 PM MST MONDAY FOR AZZ530>555-559.
EXTREME HEAT WARNING FROM 10 AM THIS MORNING TO 8 PM MST
SATURDAY FOR AZZ556-560>562.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT MONDAY FOR CAZ560>570.
SHORT TERM...18
LONG TERM...18
AVIATION...LOJERO
FIRE WEATHER...18
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