512
FXUS65 KPSR 251010
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
310 AM MST SAT JUL 25 2026
KEY MESSAGES
- MUCH ABOVE NORMAL TEMPERATURES WILL CONTINUE THROUGH THE
WEEKEND WITH READINGS APPROACHING NEAR RECORD LEVELS AND EXTREME
HEAT WARNINGS IN EFFECT.
- STRONG OUTFLOW BOUNDARY WINDS WILL MOVE THROUGH SOUTH-CENTRAL
ARIZONA LATE THIS AFTERNOON AND EVENING, WITH A SLIGHT CHANCE TO
GENERATE SHOWERS AND AND STORMS OVER THE LOWER DESERTS.
- TEMPERATURES WILL COOL SLIGHTLY EARLY NEXT WEEK AS HIGH PRESSURE
WEAKENS, BUT WILL RISE AGAIN HEADING INTO THE LATTER HALF OF THE
WEEK WITH WIDESPREAD MAJOR AND AREAS OF EXTREME HEAT RISK
RETURNING.
- TYPICAL MONSOON CONDITIONS ARE EXPECTED NEXT WEEK WITH DAILY
THUNDERSTORM CHANCES FAVORING NORTHERN ARIZONA HIGH TERRAIN AND
SOUTHEAST ARIZONA AND LOW CHANCES IN THE SOUTH-CENTRAL ARIZONA
LOWER DESERTS.
SHORT TERM /TODAY THROUGH MONDAY/
THE TEMPERATURE AT MIDNIGHT IN PHOENIX WAS 107 DEGREES, WHICH IS
QUITE FRANKLY DISGUSTING AND VERY UNPLEASANT. THIS IS NOT THE
FIRST TIME THOUGH THAT TEMPERATURES WERE THIS HOT IN THE MIDNIGHT
TO 1 AM HOUR. THE TEMPERATURE WAS 107 AT MIDNIGHT BACK ON JULY
30TH, 2023 AND WAS NEARLY AS HOT DURING THE MIDDLE OF THE SAME
MONTH, WHEN THE 97 DEGREE RECORD WARM LOW WAS FIRST SET. THERE IS
A DECENT CHANCE TO BREAK THE ALL TIME RECORD WARM LOW THIS
MORNING, ESPECIALLY CONSIDERING THE RECORD WAS TIED YESTERDAY
MORNING AND THE TEMPERATURE SHORTLY AFTER MIDNIGHT THIS MORNING
WAS 3-4 DEGREES WARMER THAN THE SAME TIME YESTERDAY MORNING.
WHETHER THE RECORD IS BROKEN IS LARGELY DEPENDENT ON THE WINDS. IF
A WESTERLY BREEZE CAN BE MAINTAINED THROUGH SUNRISE, THEN THE
RECORD WILL PROBABLY BE BROKEN AND IT IS NOT OUT OF THE REALM OF
POSSIBILITY TO SEE THE FIRST 100 DEGREE LOW.
AFTER ANOTHER HOT MORNING TEMPERATURES THIS AFTERNOON WILL AGAIN
HEAT UP TO SIMILAR LEVELS TO YESTERDAY, IF NOT 1-3 DEGREES HOTTER,
WITH LOWER DESERT HIGHS FORECAST TO REACH 114-119 DEGREES. THIS
COMBO OF FORECAST RECORD WARM LOWS AND NEAR RECORD HIGHS IS
LEADING TO WIDESPREAD MAJOR HEATRISK AND AREAS OF EXTREME HEATRISK
IN THE MOST POPULATED AREAS. COMBINING THIS WITH THE WEEKEND ONLY
INCREASES THE ALREADY HEIGHTENED RISK FOR HEAT-RELATED HEALTH
IMPACTS. EVEN THE MORNING HOURS ARE NOT RECOMMENDED FOR OUTDOOR
RECREATION GIVEN THE VERY HOT START AND RAPID WARMING THROUGH THE
MORNING - 110 DEGREES BY 11 AM. THE MUGGINESS, DEW POINT
TEMPERATURES IN THE UPPER 50S TO 60S WILL ONLY ADD TO THE
DISCOMFORT. WHILE NOT MUCH, THERE WILL BE A SMALL DEGREE OF
RELIEF TO THE TEMPERATURES, AT LEAST WITH THE HIGHS, HEADING INTO
SUNDAY AND MONDAY AS H5 HEIGHTS COME DOWN A FEW DECAMETERS AND
850MB TEMPS COOL A FEW DEGREES C. THE MORNINGS WILL REMAIN
UNCOMFORTABLE WITH LOWS IN THE UPPER 80S TO LOW 90S. HIGH
TEMPERATURES MONDAY ARE FORECAST TO DROP TO WITHIN A FEW DEGREES
ABOVE NORMAL, BUT THE ADDED HUMIDITY MAY ADD A FEW DEGREES ONTO
THE EARLY AFTERNOON APPARENT TEMPERATURES. SO, FOR NOW THE
EXTREME HEAT WARNING WILL BE MAINTAINED THROUGH MONDAY.
THE PROSPECT OF SHOWERS AND THUNDERSTORMS IN THE LOWER DESERTS OF
SOUTH-CENTRAL AZ ARE SLIGHTLY BETTER TODAY-TONIGHT THAN THEY WERE
THE PAST FEW DAYS, FOR A FEW FACTORS COMING TOGETHER. BROAD
ANTICYCLONIC FLOW REMAINS IN PLACE ACROSS THE DESERT SOUTHWEST,
WITH AN IT (BERTHA REMNANTS) SEEN MOVING ACROSS SONORA, MX THIS
MORNING AND THERE IS A SMALL MESOSCALE LOW PRESSURE OVER CENTRAL
NM. LATEST GUIDANCE SHOWS THE MESOSCALE LOW WILL PROGRESS INTO
EAST-CENTRAL AZ THIS AFTERNOON AND EVENING, ASSISTING RIM
CONVECTION AND INDUCING A LIGHT EAST-NORTHEAST STEERING WIND OFF
THE RIM. DCAPE WILL BE FAIRLY HIGH TODAY ACROSS SOUTH-CENTRAL AZ
(1200-1800 J/KG), GIVEN THE VERY HOT TEMPERATURES, AND LATEST
HREF FAVORS MODERATE TO STRONG OUTFLOWS (30-50 MPH WIND GUSTS)
MOVING OFF THE RIM INTO THE LOWER DESERTS IN THE LATE AFTERNOON
AND EVENING. IT REMAINS TO BE SEEN IF THE OUTFLOWS WILL GENERATE
NEW STORMS OVER THE LOWER DESERTS OR IF THE CAP/CIN WILL WILL BE
TOO MUCH TO OVERCOME. EVEN IF IT IS OVERCOME, SHOWERS AND STORMS
OVER THE LOWER DESERTS ARE NOT EXPECTED TO BE TOO INTENSE, DUE TO
SUB-1000 J/KG CAPE, OWING TO THE VERY WARM AIR ALOFT AND DEEP
BOUNDARY LAYER. THE STRONGEST STORMS TODAY WILL BE AROUND TUCSON
AND POINTS SOUTH, WHERE MOISTURE AND INSTABILITY WILL BE GREATEST,
WITH MODEST SHEAR (20-25 KT) AS WELL. THESE STORMS WILL LIKELY
PUSH OUTFLOWS NORTH-NORTHWESTWARD TOWARD SOUTH-CENTRAL AZ LATER
IN THE EVENING, WHICH MAY COLLIDE WITH THE SOUTHWESTWARD-MOVING
OUTFLOWS TO SPARK ACTIVITY. MID AND UPPER LEVEL ASCENT WILL
INCREASE HEADING INTO THE OVERNIGHT HOURS TONIGHT, TO PERHAPS
SUPPORT LINGERING SHOWERS DURING THE NIGHT, AS AN UPPER LEVEL JET
STREAK NUDGES IN FROM THE EAST.
HEADING INTO SUNDAY AND MONDAY, THE SYNOPTIC SETUP WILL TAKE ON
MORE OF A TRADITIONAL MONSOON REGIME WITH HIGH PRESSURE CENTERED
TO THE NORTHEAST AND INCREASING SOUTHEAST FLOW. STORMS WILL
PRIMARILY FOCUS OVER N AZ AND SE AZ, WITH THE STRONGEST STORMS
STILL NEAR THE INTERNATIONAL BORDER. DESPITE AN INCREASE IN
BOUNDARY LAYER MOISTURE (11-12 G/KG MIXING RATIOS) AND
INSTABILITY MODEL SOUNDINGS SHOW A MODERATE-STRONG CAPPING
INVERSION THAT MAY BE DIFFICULT TO OVERCOME FOR CONVECTION TO
ENSUE OVER THE LOWER DESERTS, AWAY FROM TERRAIN FEATURES. LATEST
NBM HAS 10-20% CHANCES IN MARICOPA AND NORTHERN PINAL COUNTIES
SUNDAY AND MONDAY.
LONG TERM /TUESDAY THROUGH FRIDAY/
STRONG, EXPANSIVE RIDGING WILL REMAIN NEARLY IN PLACE THROUGH 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. OVERALL,
THIS APPEARS TO BE A VERY TYPICAL MONSOON PATTERN WITH ALTERNATING
CONVECTIVELY ACTIVE AND INACTIVE DAYS. HOWEVER, 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 AND THE CENTER OF THE ANTICYCLONE SHIFTING TO 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, AFTER THE
VERY SHORT-LIVED REPRIEVE AT THE BEGINNING OF THE WEEK. AS A
RESULT, THE CURRENT EXTREME HEAT WARNING MAY ACTUALLY BE EXTENDED
AS ONE PROLONGED WARNING EVENT.
AVIATION
UPDATED AT 0515Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
GUSTY OUTFLOWS SATURDAY EVENING WILL BE THE MAIN AVIATION WEATHER
ISSUE THROUGHOUT THE TAF PERIOD. IN THE MEANTIME, THROUGH SATURDAY
AFTERNOON, FAIRLY TRANQUIL CONDITIONS WILL PREVAIL WITH WESTERLY
WINDS MOSTLY PREVAILING ACROSS MOST OF THE TERMINALS, WITH THE
ONLY EXCEPTION BEING KIWA WITH EASTERLY WINDS DURING THE OVERNIGHT
AND EARLY MORNING HOURS. SOME GUSTS INTO THE MID TO UPPER TEENS
WILL BE POSSIBLE DURING THE AFTERNOON HOURS. HEADING INTO SATURDAY
EVENING, LATEST MODEL TRENDS ARE DEPICTING A STRONG NORTH TO
NORTHEAST OUTFLOW MOVING THROUGH THE AREA BETWEEN 02-04Z, WITH
POTENTIAL PEAK GUSTS EXCEEDING 25-30 KTS. THEREAFTER, A WEAKER
SOUTHERLY OUTFLOW MAY PENETRATE THROUGH THE AREA AFTER 05-06Z WITH
THE POTENTIAL FOR SOME LOFTED DUST/HAZE. THERE IS ABOUT A 20%
CHANCE OF ISOLATED SHRA DEVELOPING ALONG THE VICINITY OF THESE
OUTFLOWS, HOWEVER, CONFIDENCE WAS TOO LOW AT THIS TIME TO MENTION
IN THE LATEST TAF PACKAGE. FEW-SCT MID TO HIGH-LEVEL CLOUD DECKS
WILL PREVAIL THROUGH SATURDAY AFTERNOON BEFORE COVERAGE INCREASES
TO BKN SATURDAY EVENING.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION WEATHER CONCERNS UNDER FEW MID TO HIGH-LEVEL
CLOUD DECKS ARE EXPECTED THROUGH SATURDAY EVENING. OVERALL WIND
PATTERN WILL CONTINUE TO FLUCTUATE BETWEEN SOUTHEAST TO SOUTHWEST
WITH SPEEDS GENERALLY UNDER 12 KTS. PERIODS OF LIGHT VARIABILITY
WILL BE LIKELY EARLY SATURDAY MORNING.
FIRE WEATHER
THUNDERSTORM CHANCES WILL REMAIN LOW TODAY WITH ONLY ISOLATED
SHOWERS AND STORMS EXPECTED OVER THE HIGH TERRAIN AREAS IN EASTERN
ARIZONA. THESE STORMS ARE EXPECTED TO BE SHORT-LIVED. 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. TEMPERATURES ARE EXPECTED TO COOL BACK TO
NEAR TO SLIGHTLY ABOVE NORMAL EARLY 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 UNTIL 8 PM MST THIS EVENING FOR AZZ556-
560>562.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT MONDAY FOR CAZ560>570.
SHORT TERM...BENEDICT
LONG TERM...18/BENEDICT
AVIATION...LOJERO
FIRE WEATHER...BERISLAVICH/18
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