965
FXUS65 KPSR 261918
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1218 PM MST SUN JUL 26 2026
UPDATE
UPDATED 18Z AVIATION DISCUSSION.
KEY MESSAGES
- ABOVE NORMAL TEMPERATURES WILL CONTINUE THROUGH THE START OF
THE WORKWEEK WITH EXTREME HEAT WARNINGS REMAINING IN EFFECT.
- TYPICAL MONSOON CONDITIONS ARE EXPECTED INTO NEXT WEEK WITH
DAILY THUNDERSTORM CHANCES FAVORING NORTHERN ARIZONA HIGH
TERRAIN AND SOUTHEAST ARIZONA AND LOW CHANCES IN THE SOUTH
CENTRAL ARIZONA LOWER DESERTS.
- AFTER A SLIGHT DROP IN TEMPERATURES DURING THE FIRST HALF OF
THE COMING WORKWEEK, HIGH PRESSURE WILL STRENGTHEN OVER THE
REGION ONCE AGAIN LATE IN THE WEEK, RESULTING IN ANOTHER PERIOD
OF UNSEASONABLY HOT TEMPERATURES AND A RETURN OF WIDESPREAD
MAJOR HEAT RISK.
SHORT TERM /TODAY THROUGH WEDNESDAY/
SATELLITE OBSERVATIONS EARLY THIS MORNING SHOWS THE LARGE MONSOON
HIGH ENCOMPASSING THE DESERT SOUTHWEST AND THE PLAINS, WITH THE
CENTRAL ANTICYCLONE NEAR THE CO-NM BORDER. THERE WERE ALSO TWO
FEATURES EVIDENT IN IR, REMNANT WEAK VORTICITY OVER NORTHERN AZ
AND THE REMNANTS OF TC BERTH STILL MOVING NORTHWEST THROUGH
NORTHERN BAJA AND SOCAL. THE INTERACTION OF BERTHA REMNANTS WITH
THE FAR-TRAVELING OUTFLOW BOUNDARY FROM SATURDAY AFTERNOON AZ
STORMS HELPED SPARK SPOTTY CONVECTION IN SOUTHEAST CA. THE
SYNOPTIC PATTERN TODAY THROUGH TUESDAY WILL SEE MINIMAL CHANGES,
WITH OVERALL LOW-GRADE MONSOON CONDITIONS FAVORED. GUIDANCE KEEPS
THE MONSOON HIGH POSITIONED OVER NORTHERN NM THROUGH THE FIRST
HALF OF THE WEEK, WITH A GRADUAL WEAKENING OF THE HIGH PRESSURE AS
WELL - H5 HEIGHTS OVER AZ DROPPING FROM 597-598DAM TODAY TO
594-594DAM TUESDAY. BOUNDARY LEVEL MOISTURE WILL REMAIN DECENT
ACROSS THE AZ DESERTS - MIXING RATIOS AROUND 9-11 G/KG AND AVERAGE
SURFACE DEW POINTS IN THE UPPER 50S TO LOWER 60S - TO SUPPORT
DAILY AFTERNOON THUNDERSTORMS, BUT STORMS WILL MOSTLY REMAIN
FOCUSED OVER THE NORTHERN AZ HIGH TERRAIN AND SOUTHEAST AZ.
MEANWHILE THE ENVIRONMENT OVER THE LOWER DESERTS OF SOUTH-CENTRAL
AND SOUTHWEST AZ WILL MOSTLY BE SUB- OPTIMAL FOR ANY ROBUST
CONVECTIVE DEVELOPMENT, WITH MUCAPE VALUES FORECAST TO MOSTLY STAY
BELOW 1000 J/KG AND A MODEST CAP WITH CIN STAYING MOSTLY <-25
J/KG. STILL, A FEW STORMS MAY DEVELOP OVER TERRAIN FEATURES OF LA
PAZ COUNTY AND THE TABLE TOP AREA IN SOUTHERN MARICOPA COUNTY.
THROUGH THE SHORT TERM, AND LONG TERM, THE PRIMARY WEATHER HAZARD
WILL CONTINUE TO BE DANGEROUSLY HOT TEMPERATURES. AN EXTREME HEAT
WARNING REMAINS IN EFFECT THROUGH MONDAY FOR THE MAJORITY OF THE
DESERTS. HIGH TEMPERATURES WILL NOT BE QUITE AS HIGH THE NEXT FEW
DAYS AS THEY WERE THE PREVIOUS FEW DAYS, WITH THE SLIGHT WEAKENING
OF THE HIGH PRESSURE, AND THERE WILL BE A DOWNTREND IN THE
HEATRISK LEVEL WITH A REDUCTION IN THE COVERAGE OF MAJOR HEATRISK.
LOWER DESERT HIGHS THE NEXT FEW DAYS WILL BE IN THE 107-114F
RANGE, WHICH IS AROUND 3-6F ABOVE NORMAL. ALTHOUGH IT IS NOT TOO
UNUSUAL TO SEE HIGHS OF THIS MAGNITUDE THIS TIME OF THE YEAR, THE
LOW TEMPERATURES WILL CONTINUE TO BE VERY WARM EACH MORNING AND
WILL BE THE PRIMARY DRIVER OF THE LINGERING AREAS OF MAJOR
HEATRISK. MOST LOWER DESERTS WILL ONLY COOL OFF INTO THE UPPER 80S
TO LOWER 90S. THIS DOES NOT OFFER MUCH RELIEF FROM THE HEAT AND
ALLOWS TEMPERATURES TO SOAR QUICKLY INTO THE 100S BY 10-11 AM EACH
MORNING. THE EXTREME HEAT WARNING IS STILL BEING CONSIDERED FOR
EXTENSION BEYOND MONDAY TO CARRY RIGHT INTO THE NEXT EXTREME HEAT
EVENT LATER IN THE WEEK AS THE MONSOON HIGH RESTRENGTHENS AND
REPOSITIONS DIRECTLY OVER AZ. THIS WILL LEAVE ONLY A BRIEF
REPRIEVE FROM WIDESPREAD MAJOR HEATRISK. TUESDAY CURRENTLY LOOKS
LIKE THE "COOLEST" DAY, WITH ONLY ISOLATED COVERAGE OF MAJOR
HEATRISK.
LONG TERM /THURSDAY THROUGH SUNDAY/
BY THE LATTER HALF OF THE WEEK, MOST GLOBAL ENSEMBLES SUPPORT
NOTABLE STRENGTHENING OF THE HIGH PRESSURE, WITH 600DAM H5 HEIGHTS
MATERIALIZING AND THE CENTER OF THE ANTICYCLONE SHIFTING TO OVER
NORTHERN AZ/SOUTHERN UT. THE PRIMARY IMPACT OF THIS OUTCOME WILL
BE ANOTHER EXTREME HEAT EVENT WITH A RETURN OF WIDESPREAD MAJOR
HEATRISK AND AREA OF EXTREME HEATRISK, BEGINNING AS EARLY AS
THURSDAY AND THE HEAT LIKELY PEAKING ON FRIDAY AND SATURDAY. THERE
IS ALREADY HIGH ENOUGH CONFIDENCE TO WARRANT EXTREME HEAT
HEADLINES AND THE ISSUANCE OF AN EXTREME HEAT WARNING, BUT IT IS
STILL BEING CONSIDERED WHETHER TO JUST EXTEND THE CURRENT EXTREME
HEAT WARNING THROUGH THE BRIEF REPRIEVE TUESDAY-WEDNESDAY OR
SEPARATE THE EVENTS. THIS FORECAST OUTCOME WILL ALSO LIKELY ADD
MORE SUBSIDENCE OVER THE AREA AND SUBDUE AFTERNOON CONVECTION.
GLOBAL ENSEMBLES ALSO SHOW A SLOW DOWNTREND IN PWATS, FALLING
UNDER 1.5" BY THURSDAY-FRIDAY. SO, THIS IS NOT GREAT FOR THE
PROSPECTS OF SEEING STORMS PUSH INTO THE LOWER DESERTS. LATEST NBM
KEEPS SLIGHT POPS FOCUSED IN THE AZ HIGH TERRAIN. THE ONE
POTENTIAL OUTCOME THAT COULD INCREASE CHANCES FOR STORMS INTO THE
LOWER DESERTS HOWEVER IS IF THE ANTICYCLONE CAN REPOSITION CLOSER
TO SOUTHERN NV, IN A MADDOX TYPE II POSITION, TO PROVIDE STRONGER
E-NE WINDS OVER THE RIM.
AVIATION
UPDATED AT 1905Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
WESTERLY WINDS WILL CONTINUE THROUGH THE OVERNIGHT HOURS. WIND
SPEEDS WILL GENERALLY BE AROUND 7-13 KT THROUGH THE AFTERNOON, BUT
SOME OCCASIONAL GUSTS INTO THE MID TO UPPER TEENS IS POSSIBLE. A
GULF SURGE LOOKS TO MOVE INTO THE AREA THIS EVENING (00-04Z),
KEEPING WINDS WESTERLY, BUT SOME GUSTS UP AROUND 20 KT IS POSSIBLE
AT KPHX. THE GULF SURGE LOOKS LIKE IT WILL WASH OUT OR AT LEAST
NOT HAVE GUSTS WITH IT BY THE TIME IT REACHES THE OTHER THREE
TERMINALS. A COMPLEX OF THUNDERSTORMS IS EXPECTED TO DEVELOP IN
SONORA MEXICO THIS EVENING. THIS COMPLEX MAY SEND AN OUTFLOW INTO
THE VALLEY AROUND SUNRISE TOMORROW MORNING. NO GUSTS ARE EXPECTED,
IT WOULD JUST BE A SHIFT TO S/SE AROUND 11-12Z AT KPHX AND KIWA.
THIS OUTFLOW IS NOT EXPECTED TO REACH KSDL AND KDVT AND THEIR
WINDS ARE JUST EXPECTED TO GO LIGHT AND VARIABLE TOMORROW MORNING.
IF THE OUTFLOW WASHES OUT PRIOR TO REACHING KPHX AND KIWA, WINDS
MAY STAY WESTERLY TOMORROW MORNING OR GO LIGHT AND VARIABLE. WINDS
ARE THEN EXPECTED TO RETURN TO A MORE DIURNAL PATTERN LATE
TOMORROW MORNING WITH WESTERLY WINDS DEVELOPING AND SOME
OCCASIONAL GUSTS INTO THE UPPER TEENS TOMORROW AFTERNOON. FEW TO
SCT MID AND HIGH LEVEL CLOUDS WILL CONTINUE.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
SOME LIGHT SHOWERS HAVE MOVED INTO SW IMPERIAL COUNTY AND THE
IMPERIAL VALLEY. THESE SHOWERS ARE EXPECTED TO DISSIPATE AROUND
21Z. SOUTHERLY WINDS ARE ANTICIPATED AT KIPL THROUGH THE EVENING
WITH SPEEDS IN THE LOW TO MID TEENS, WITH SOME OCCASIONAL GUSTS UP
AROUND 20 KT POSSIBLE. WINDS WILL THEN GO BACK SE'RLY DURING THE
OVERNIGHT HOURS, WITH SPEEDS GOING BACK BELOW 10 KT. AT KBLH,
SOUTHERLY WINDS ARE ANTICIPATED THROUGH THE WHOLE PERIOD WITH
SPEEDS AROUND 10-15KT, BUT SOME OCCASIONAL GUSTS AROUND 20 KT ARE
POSSIBLE THIS AFTERNOON. A GULF SURGE IS THEN EXPECTED LATE
TONIGHT. THIS WILL KEEP WINDS SOUTHERLY, BUT GUSTS UP AROUND 20 KT
WILL AGAIN BE POSSIBLE BETWEEN 05-08Z. CURRENT SCT-BKN MID AND
HIGH CLOUDS WILL BECOME FEW-SCT DURING THE OVERNIGHT HOURS.
FIRE WEATHER
TYPICAL MONSOON CONDITIONS ARE EXPECTED THROUGH MUCH OF THE
FORECAST, WITH DAILY THUNDERSTORM ACTIVITY MAINLY FAVORING THE
HIGH TERRAIN OF NORTHERN AZ AND SOUTHEASTERN AZ AND LOW CHANCES
(10%) IN THE LOWER DESERTS OF SOUTH-CENTRAL AZ. ABOVE NORMAL,
TEMPERATURES WILL CONTRIBUTE TO SEASONALLY DRY AFTERNOON
CONDITIONS EACH DAY THROUGH THE FIRST HALF OF THE WEEK, BEFORE
TEMPERATURES ONCE AGAIN HEAT UP DURING THE SECOND HALF OF THE
WEEK. MINIMUM RH VALUES OF 20-30% WILL BE COMMON THROUGH THE FIRST
HALF OF THE WEEK BEFORE DROPPING INTO THE 10-25% RANGE LATE IN
THE WEEK AS TEMPERATURES HEAT UP AGAIN. OVERNIGHT RECOVERIES WILL
BE FAIR MOST NIGHTS WITH RH VALUES MOSTLY IN THE 35-50% ACROSS
LOWER DESERTS TO 45-65% ACROSS SOUTHERN GILA COUNTY. 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 WEDNESDAY FOR AZZ530-532-537-
540-542>544-546-548-550-551.
EXTREME HEAT WARNING UNTIL 8 PM MST MONDAY FOR AZZ531-533>536-
538-539-541-545-547-549-552>555-559.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT WEDNESDAY FOR CAZ567-569-570.
EXTREME HEAT WARNING UNTIL 8 PM PDT MONDAY FOR CAZ560>566-568.
SHORT TERM...BENEDICT
LONG TERM...BENEDICT
AVIATION...BERISLAVICH
FIRE WEATHER...BENEDICT
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