917
FXUS65 KPSR 211010
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
310 AM MST TUE JUL 21 2026
KEY MESSAGES
- SHOWER AND THUNDERSTORM CHANCES WILL CONTINUE TODAY, ESPECIALLY
OVER THE ARIZONA HIGH TERRAIN. ISOLATED STORMS AND GUSTY STORM
OUTFLOW WINDS CAN ALSO BE EXPECTED INTO THE SOUTH-CENTRAL
ARIZONA LOWER DESERTS.
- DRYING CONDITIONS STARTING WEDNESDAY WILL MOSTLY END MONSOON
STORM CHANCES BY THURSDAY.
- EXTREME HEAT WATCHES ARE IN EFFECT FOR ALL OF THE LOWER DESERTS
FOR THE LATTER HALF OF THE WEEK AS HOT AND HUMID CONDITIONS WILL
DEVELOP OVER THE NEXT COUPLE OF DAYS.
SHORT TERM /TODAY THROUGH WEDNESDAY/
ACTIVE MONSOON WEATHER WILL CONTINUE FOR ONE MORE DAY THIS WEEK AS
A DISTINCT EASTERLY INVERTED TROUGH CONTINUES TO TRACK
NORTHWESTWARD THROUGH NEW MEXICO EARLY THIS MORNING AND THEN
THROUGH THE NORTHEASTERN 1/3 OF ARIZONA THIS AFTERNOON/EVENING.
THE ATMOSPHERE WILL HOWEVER HAVE TO RECOVER A BIT AFTER THE
COMPLEX OF SHOWERS AND STORMS THAT AFFECTED THE ARIZONA HIGH
TERRAIN BEFORE DYING AS IT MOVED INTO THE PHOENIX AREA. CURRENTLY,
THERE IS LITTLE AVAILABLE CAPE, BUT LINGERING ASCENT FROM AN MCV
JUST NORTH OF PHOENIX AND BROAD SCALE UPPER LEVEL ASCENT FROM THE
INCOMING INVERTED TROUGH MAY BE ENOUGH FOR SOME ISOLATED ELEVATED
SHOWERS THROUGH SUNRISE.
FOR THIS AFTERNOON AND EVENING, HI-RES CAMS ARE PAINTING A SIMILAR
PICTURE TO WHAT OCCURRED YESTERDAY. WIDESPREAD SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS EASTERN ARIZONA THIS
AFTERNOON WITH HEAVY RAINFALL AND LOCALIZED FLOODING BEING THE
MAIN THREATS. A FLOOD WATCH FOR THIS AFTERNOON THROUGH MID EVENING
COVERS MUCH OF THE ARIZONA HIGH TERRAIN WHERE LOCALIZED AMOUNTS OF
GREATER THAN 2" WILL BE POSSIBLE. ANOTHER POTENTIAL LINE OF STORMS
OR EVEN A MORE ORGANIZED MCS IS QUITE LIKELY TO APPROACH THE
LOWER DESERTS THIS EVENING. HOWEVER, MUCH MORE LIMITED
INSTABILITY OVER THE SOUTH-CENTRAL ARIZONA LOWER DESERTS IS
EXPECTED TO CAUSE THE STORMS TO DIMINISH IN STRENGTH AND COVERAGE
AS THEY ATTEMPT TO PUSH THROUGH PINAL AND MARICOPA COUNTIES. GUSTY
OUTFLOW WINDS OF 35-50 MPH SEEM QUITE PLAUSIBLE FOR THE PHOENIX
AREA THIS EVENING WITH AT LEAST SOME AREAS SEEING SOME MEASURABLE
RAINFALL, THOUGH MOST AREAS ARE NOT LIKELY TO SEE MORE THAN 0.25".
STARTING WEDNESDAY, DRIER AIR WILL BE ADVECTING INTO THE AREA FROM
THE SOUTH SOUTHWEST WHILE THE INVERTED TROUGH EXITS NORTHWARD INTO
UTAH. SHOWER AND STORM CHANCES WEDNESDAY WILL BE MUCH MORE LIMITED
COMPARED TO TODAY WITH ONLY 15-30% POPS OVER THE ARIZONA HIGH
TERRAIN TO LESS THAN 10% ACROSS THE LOWER DESERTS. TEMPERATURES
WILL BECOME THE MAIN FORECAST CONCERN BEGINNING WEDNESDAY AS THE
SUBTROPICAL RIDGE SHIFTS SOUTHWARD INTO THE SOUTHERN PLAINS WHILE
ALSO NUDGING MORE INTO OUR REGION, PUSHING OUR H5 HEIGHTS TO
592-594DM. ALTHOUGH FORECAST HIGHS WEDNESDAY ARE RIGHT AROUND
NORMAL, IT WILL BE A FAIRLY MUGGY DAY FOR OUR AREA WITH SURFACE
DEW POINTS STILL IN THE 60S IN MOST AREAS. EXTREME HEAT WATCHES
ARE IN EFFECT FOR SOUTHEAST CALIFORNIA STARTING WEDNESDAY WITH
AFTERNOON HEAT INDICES (FEELS LIKE TEMPERATURES) TOPPING 110
DEGREES IN MANY SPOTS.
LONG TERM /THURSDAY THROUGH MONDAY/
EXTREME HEAT IS EXPECTED TO IMPACT MUCH OF THE AREA LATE THIS
WEEK THROUGH AT LEAST THE WEEKEND AS THE SUBTROPICAL RIDGE
STRENGTHENS WHILE THE CENTER GRADUALLY SHIFTS OVER THE REGION
FRIDAY INTO SATURDAY. RECORD OR NEAR RECORD CLIMATOLOGICAL H5
HEIGHTS ARE FORECAST ACROSS NEW MEXICO STARTING THURSDAY,
EVENTUALLY MOVING INTO ARIZONA FRIDAY INTO SATURDAY WITH H5
HEIGHTS POTENTIALLY REACHING 598-600DM OVER ARIZONA. MAJOR
HEATRISK IS EXPECTED TO IMPACT ALL OF THE LOWER DESERTS STARTING
THURSDAY, BECOMING EVEN MORE WIDESPREAD FRIDAY INTO THE WEEKEND AS
LOCALIZED AREAS OF EXTREME HEATRISK MAY DEVELOP. THE FORECAST
HIGHS OF 110-116 DEGREES THURSDAY THROUGH NEXT MONDAY (BELOW
RECORDS) IS MASKING THE POTENTIAL SEVERITY OF THIS HEAT WAVE AS
DEW POINTS AND HUMIDITIES ARE EXPECTED TO REMAIN ELEVATED. HEAT
INDICES ARE LIKELY TO REACH 113-120 DEGREES OVER THE LOWER DESERTS
STARTING FRIDAY WITH THE HIGHEST READINGS ACROSS SOUTHWEST
ARIZONA AND SOUTHEAST CALIFORNIA. OVERNIGHT LOWS WILL ALSO BECOME
VERY WARM WITH READINGS NOT LIKELY FALLING MUCH BELOW THE UPPER
80S. LOWER 90S CAN BE EXPECTED FOR MUCH OF THE URBAN CORE OF
PHOENIX STARTING THURSDAY NIGHT. IF WE DO END UP MIXING OUT MORE
OF THE BOUNDARY LAYER MOISTURE, THE HIGHER END OF NBM GUIDANCE
SHOWS HIGHS POTENTIALLY REACHING 116-118 DEGREES IN THE PHOENIX
AREA TO AS HIGH AS 117-120 DEGREES FOR PORTIONS OF SOUTHEAST
CALIFORNIA.
THE HOTTEST DAYS ARE LIKELY TO BE FRIDAY-SUNDAY, BUT THERE IS MORE
FORECAST UNCERTAINTY BY SUNDAY AS SOME GUIDANCE INDICATES SOME
MOISTURE RETURN THIS WEEKEND AND THE POTENTIAL FOR MORE
CONVECTIVE ACTIVITY. FOR NOW, WE ARE NOT EXPECTING MUCH IF ANY
HIGH TERRAIN SHOWERS OR THUNDERSTORMS THURSDAY AND FRIDAY, BUT
THAT COULD CHANGE STARTING SATURDAY OR SUNDAY. ANY MORE EXTENSIVE
CONVECTIVE ACTIVITY MAY EVENTUALLY DISRUPT THE EXTREME HEAT, AT
LEAST OVER EASTERN AND POSSIBLY INTO CENTRAL ARIZONA BY SUNDAY OR
MONDAY. IF WE DON'T GET RELIEF FROM STORM ACTIVITY, GUIDANCE AT
LEAST HEAVILY FAVORS SOME WEAKENING OF THE RIDGE EARLY NEXT WEEK
WHILE ALSO SHIFTING IT FARTHER TO THE EAST.
AVIATION
UPDATED AT 1100Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
GUSTY OUTFLOW WINDS AND MODEST CHANCES FOR TSRA THIS EVENING ARE THE
PRIMARY WEATHER ISSUES UNDER PERIODS OF MID/HIGH CLOUD DECKS.
CONFIDENCE IS GOOD THAT PREVAILING EAST WINDS WILL SWITCH TO W/SW BY
NOON WITH ONLY SOME MINOR AFTERNOON GUSTINESS. TSRA FORMING OVER
HIGHER TERRAIN TO THE EAST SHOULD SEND GUSTY OUTFLOWS AND AN ABRUPT
WIND SHIFT TOWARDS THE PHOENIX TERMINALS. CONFIDENCE IS FAIR THAT
WIND SPEEDS WILL BE WEAKER THAN MONDAY, YET STILL POSSIBLY 25-35KT.
THE CHANCE FOR DIRECT TSRA IMPACTS ON ANY GIVEN AERODROME IS ALSO
LOWER THAN MONDAY, BUT STILL NEARLY A 30% CHANCE OF SOME SHRA BEHIND
THE OUTFLOW BOUNDARY.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR WEATHER ISSUES WILL EXIST THROUGH WEDNESDAY MORNING UNDER
A FEW PASSING MID/HIGH CLOUD DECKS. WINDS WILL GENERALLY FAVOR A
SOUTH DIRECTION AT KBLH, WHILE DIRECTIONS SHOULD BE MORE VARYING
AT KIPL BETWEEN SOUTH AND WEST. THERE MAY BE SUNDOWNER GUSTS OVER
20KT AT KIPL THIS EVENING, HOWEVER CONFIDENCE IN EXPANSE AND
DURATION OF GUSTY WINDS IS LOW.
FIRE WEATHER
MUCH OF THE SHOWER AND THUNDERSTORM ACTIVITY WILL BE OVER THE
ARIZONA HIGH TERRAIN TODAY WHILE GUSTY STORM OUTFLOW WINDS WILL
BE THE MAIN CONCERN TODAY FOR THE SOUTH-CENTRAL ARIZONA LOWER
DESERTS. CHANCES FOR SHOWERS AND STORMS WILL QUICKLY DROP OFF
WEDNESDAY WITH LITTLE IF ANY ACTIVITY EXPECTED THURSDAY AS HOTTER
AND DRIER CONDITIONS SETTLE INTO THE REGION. HUMIDITIES WILL
REMAIN ELEVATED TODAY WITH MINRHS OF 30-45% ACROSS THE EASTERN
DISTRICTS, WHILE THE WESTERN DISTRICTS WILL DIP TO 20-25%. MINRHS
WILL THEN DIP TO 15-20% ACROSS ALL OF THE LOWER DESERTS STARTING
THURSDAY.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WATCH FROM WEDNESDAY MORNING THROUGH MONDAY EVENING
FOR AZZ530-532.
FLOOD WATCH FROM 11 AM MST THIS MORNING THROUGH THIS EVENING FOR
AZZ556-560-562-563.
EXTREME HEAT WATCH FROM THURSDAY MORNING THROUGH MONDAY EVENING
FOR AZZ531-533>555-559.
CA...EXTREME HEAT WATCH FROM WEDNESDAY MORNING THROUGH MONDAY EVENING
FOR CAZ562>570.
EXTREME HEAT WATCH FROM THURSDAY MORNING THROUGH MONDAY EVENING
FOR CAZ560-561.
SHORT TERM...KUHLMAN
LONG TERM...KUHLMAN
AVIATION...18
FIRE WEATHER...KUHLMAN
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