756
FXUS65 KPSR 202102
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
202 PM MST THU AUG 20 2026
KEY MESSAGES
- AFTER A BRIEF REPRIEVE FROM THE EXTREME HEAT TODAY OVER SOUTH-
CENTRAL AND EASTERN ARIZONA, HIGHS WILL RETURN TO AROUND 110
DEGREES BY FRIDAY, LASTING INTO EARLY NEXT WEEK.
- EXTREME HEAT WARNINGS ARE IN EFFECT THROUGH SUNDAY EVENING DUE TO
CONTINUED AREAS OF HIGH-END MODERATE TO MAJOR HEATRISK.
- ISOLATED THUNDERSTORMS ARE EXPECTED ACROSS THE AZ HIGH TERRAIN
THIS AFTERNOON AND EVENING WITH LESS THAN 10% CHANCES FOR THE
LOWER DESERTS. CHANCES WILL LIKELY REMAIN CONFINED TO THE HIGH
TERRAIN THROUGH AT LEAST SATURDAY.
SHORT TERM /TODAY THROUGH SATURDAY/
AFTER THE BIGGEST MONSOON EVENT OF THE SEASON SO FAR IN THE
PHOENIX METRO AREA, WE ARE NOT ANTICIPATING MUCH IF ANY ACTIVITY
IN THE LOWER DESERTS TODAY DUE TO AN OVERTURNED ATMOSPHERE. LATEST
VISIBLE SATELLITE AND COMPOSITE RADAR IMAGERY REVEALS A REMNANT
MCV LEFT OVER FROM LAST NIGHT'S STORM COMPLEX WHICH IS NOW
PROGRESSING THROUGH THE YUMA AREA. THIS MCV IS EXPECTED TO
CONTINUE BRINGING AN AREA OF LIGHT TO MODERATE SHOWERS WITH A FEW
EMBEDDED LIGHTNING STRIKES TO YUMA AND IMPERIAL COUNTIES OVER THE
NEXT FEW HOURS BEFORE FINALLY DISSIPATING. FARTHER EAST, SKIES
HAVE CLEARED OUT ACROSS SOUTHCENTRAL AZ ALLOWING TEMPERATURES TO
BEGIN RISING, HOWEVER HIGHS IN THE PHOENIX AREA WILL LIKELY TOP
OUT RIGHT AROUND NORMAL DUE TO RESIDUAL MOISTURE FROM PREVIOUS
RAINFALL. THEREFORE, NBM HIGH TEMPERATURES WERE ADJUSTED DOWN BY
SEVERAL DEGREES THIS AFTERNOON AND OVERNIGHT LOWS TONIGHT AS WELL.
LATEST RAP 13 MESOANALYSIS ACROSS SOUTHCENTRAL AZ SHOWS CAPE
VALUES ARE STILL AROUND 1000-1200 J/KG, BUT THERE IS A MUCH
STRONGER MID-LVL INVERSION TODAY WITH ML CIN ON THE ORDER -120
TO -150 J/KG. THEREFORE STORM COVERAGE WILL BE MUCH MORE ISOLATED
THIS AFTERNOON, AND WITHOUT A STRONG OUTFLOW, LITTLE TO NO STORMS
ARE EXPECTED ACROSS THE LOWER DESERTS THIS AFTERNOON AND EVENING.
DETERMINISTIC MODELS AND ENSEMBLE MEMBERS SUGGEST THE SUBTROPICAL
HIGH WILL SHIFT OVER COLORADO ON FRIDAY AND THEN MIGRATE INTO
EASTERN NM ON SATURDAY. THIS SHIFT IN THE UPPER-LVL PATTERN WILL
CAUSE WINDS TO TURN MORE OUT OF THE SOUTH, USHERING DRIER AIR INTO
OUR BEGINNING ON FRIDAY. BOTH THE GEFS AND ECS SHOW PWATS FALLING
TO 1.3" OR LOWER AND MIXING RATIOS AS LOW AS 7-8 G/KG. AS SUCH,
NBM POPS FOR BOTH FRIDAY AND SATURDAY FALL BELOW 10% FOR THE LOWER
DESERTS TO 10-20% OVER PORTIONS OF THE HIGH TERRAIN. DESPITE
STORM COVERAGE DECREASING SUBSTANTIALLY, THERE WILL STILL BE A
CHANCE OF A DISTANT OUTFLOW FROM STORMS ALONG THE INTERNATIONAL
BORDER REACHING MARICOPA OR PINAL COUNTIES, BUT ADDITIONAL STORM
DEVELOPMENT IS UNLIKELY. ALTHOUGH THE RIDGE AXIS WILL SHIFT EWD
INTO THIS WEEKEND, OVERALL 500 MB HGHT FIELDS WILL REMAIN LARGELY
UNCHANGED FROM PREVIOUS DAYS. THEREFORE, WE SHOULD SEE A RETURN OF
ABOVE NORMAL TEMPERATURES AND EXTREME HEAT CONDITIONS BY FRIDAY
AND PERSISTING INTO THIS WEEKEND AND THE EXTREME HEAT WARNING WILL
REMAIN IN EFFECT THROUGH SUNDAY.
LONG TERM /SUNDAY THROUGH WEDNESDAY/
MODEL UNCERTAINTY REMAINS QUITE HIGH FOR THE FIRST HALF OF NEXT
WEEK AS THE POSITION OF THE HIGH IS LIKELY TO SET UP SOMEWHERE
OVER EASTERN NEW MEXICO AND WESTERN TEXAS BY MONDAY WITH LITTLE TO
NO MOVEMENT INTO THE MIDDLE OF NEXT WEEK. THIS POSITION CAN CAUSE
HIGHER UNCERTAINTY IN MOISTURE LEVELS FOR OUR AREA WITH THE
LATEST GUIDANCE TRYING TO ADVECT SOME MOISTURE INTO OUR AREA BY
SUNDAY OR MONDAY, BUT NBM FORECAST POPS ARE AT MOST 10-15% FOR THE
LOWER DESERTS. AT THIS POINT, WE COULD CONTINUE TO SEE MOSTLY
SLIGHT CHANCES FAVORING THE HIGH TERRAIN INTO EARLY NEXT WEEK, BUT
IF MOISTURE DOES EVENTUALLY IMPROVE ENOUGH STORM CHANCES ARE
LIKELY TO BE HIGHER THAN WHAT THE NBM IS DEPICTING. ANOTHER
WILDCARD WILL BE THE POTENTIAL INFLUENCE OF AN UPPER LEVEL TROUGH
THAT MAY ATTEMPT TO MOVE INTO WESTERN PORTIONS OF OUR REGION
SUNDAY INTO MONDAY. IF THIS OCCURS, IT MAY BE ENOUGH TO IMPROVE
CONVECTIVE POTENTIAL ACROSS SOUTHEAST CALIFORNIA AND WESTERN
ARIZONA FOR SUNDAY AND/OR MONDAY.
TEMPERATURES ARE EXPECTED TO CONTINUE TO BE MORE INFLUENCED BY THE
STRONG SUBTROPICAL HIGH AS H5 HEIGHTS HOVER BETWEEN 593-596DM
ACROSS THE DESERT SOUTHWEST THROUGH EARLY NEXT WEEK. DAYTIME HIGHS
ARE NOT EXPECTED TO CHANGE MUCH DAY TO DAY FROM SUNDAY THROUGH
EARLY NEXT, BARRING ANY SIGNIFICANT CHANGE WITH THE CONVECTIVE
CHANCES. THE EXTREME HEAT WARNING IS CURRENTLY IN EFFECT THROUGH
SUNDAY, BUT IT SEEMS QUITE LIKELY IT WILL NEED TO BE EXTENDED
AGAIN AT SOME POINT.
AVIATION
UPDATED AT 1818Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
A DOWN DAY IN TERMS OF THUNDERSTORM ACTIVITY IS EXPECTED FOR THE
PHOENIX AREA, WITH PRIMARILY JUST OUTFLOW PASSAGE POTENTIAL THIS
EVENING. W'RLY WINDS ARE EXPECTED THROUGH THIS EVENING, AHEAD OF
ANY OUTFLOW WINDS FROM THE NORTH AND/OR NORTHEAST. TIMING OF ANY
OUTFLOWS ARE MOST LIKELY BETWEEN 03-07Z. OUTFLOW GUSTS TO 20-25
KTS ARE POSSIBLE, BUT THE OUTFLOWS MAY JUST SERVE AS A WIND SHIFT,
WITH E'RLY WINDS THEN PREVAILING THE REST OF THE NIGHT. VCSH/VCTS
IS NOT EXPECTED AT TERMINALS THIS EVENING/TONIGHT, BUT THERE WILL
REMAIN A 10-15% CHANCE. FEW MID AND HIGH CLOUDS ARE EXPECTED
THROUGH THE AFTERNOON, FOLLOWED BY SCT TO BKN THIS EVENING AND
TONIGHT.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
A COMPLEX OF RAIN SHOWERS WITH EMBEDDED LIGHTNING IS CURRENTLY
SLOWLY MOVING WEST INTO IMPERIAL COUNTY. THIS COMPLEX IS EXPECTED
TO CONTINUE WESTWARD THROUGH THIS AFTERNOON, BUT THE RAIN MAY
GRADUALLY DISSIPATE WITH TIME. VCSH WAS ADDED TO THE KIPL TAF FOR
THE AFTERNOON AND VCTS CANNOT BE RULED OUT. WINDS WILL EVENTUAL
SHIFT MORE SE'RLY AS THE COMPLEX NEARS THE TERMINAL. A SHIFT IN
THE WIND TO MORE OF A W/SW DIRECTION IS ANTICIPATED THIS EVENING
AS THE COMPLEX SHIFTS WEST AND STORMS IN THE MOUNTAINS TO THE WEST
MAY PUSH OUTFLOWS TO KIPL. AT KBLH A S/SW WIND COMPONENT IS
EXPECTED THROUGH THE TAF PERIOD. BOTH TERMINALS WILL SEE WIND
SPEEDS MOSTLY AT OR BELOW 12 KTS SUSTAINED, WHILE KIPL MAY SEE
GUSTS UP TO 20-25 KTS THIS AFTERNOON AND EVENING. FEW-SCT CLOUD
DECKS WILL BE PRESENT THROUGH MUCH OF THE FORECAST WINDOW, WITH
THE LOWEST BASES AROUND 12 KFT.
FIRE WEATHER
ELEVATED MOISTURE LEVELS WILL PERSIST TODAY WITH A TEMPORARY
REPRIEVE FROM THE EXTREME HEAT ACROSS MUCH OF THE AREA. EXPECT
MAINLY ISOLATED SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND
EARLY EVENING OVER THE AZ HIGH TERRAIN, WITH A LESS THAN 10%
CHANCE OF STORMS IN THE LOWER DESERTS. DRIER AIR WILL FILTER INTO
THE REGION FRIDAY AND SATURDAY WITH EVEN LOWER CHANCES FOR RAIN
WHILE TEMPERATURES HEAT BACK UP TO EXTREME LEVELS. MINRHS OF
20-30% TODAY WILL LOWER TO 15-25% BEGINNING FRIDAY. WINDS SHOULD
OVERALL FOLLOW THE TYPICAL DIURNAL TENDENCIES WITH SOME MODEST
AFTERNOON UPSLOPE GUSTINESS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING UNTIL 8 PM MST SUNDAY FOR AZZ530>544-546-
548>551-553>555-559-560.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT SUNDAY FOR CAZ562-565>567-
569-570.
SHORT TERM...SALERNO
LONG TERM...KUHLMAN
AVIATION...BENEDICT
FIRE WEATHER...KUHLMAN/SALERNO
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