164
FXUS65 KPSR 160957
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
257 AM MST THU JUL 16 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- HOT AND MUGGY CONDITIONS WILL CONTINUE TODAY ACROSS THE WESTERN
DESERTS, HOWEVER TEMPERATURES WILL BEGIN TO COOL ACROSS MUCH OF
ARIZONA DROPPING TO BELOW NORMAL FRIDAY THROUGH THE WEEKEND.
- SHOWERS AND THUNDERSTORMS ARE EXPECTED TO BECOME MORE WIDESPREAD
ACROSS EASTERN AND CENTRAL ARIZONA BY THIS EVENING AND LAST INTO
EARLY FRIDAY WITH THE POTENTIAL FOR HEAVY RAINFALL AND LOCALIZED
FLASH FLOODING.
- A DECREASE IN MONSOON ACTIVITY IS EXPECTED STARTING SATURDAY
WITH CHANCES FAVORING THE ARIZONA HIGH TERRAIN.
SHORT TERM /TODAY THROUGH FRIDAY/
EARLY MORNING CONVECTION PERSISTS, BUT IS CONSIDERABLY MORE
ISOLATED COMPARED TO WEDNESDAY EVENING. SCATTERED SHOWERS AND A
FEW THUNDERSTORMS WILL CONTINUE TO BE POSSIBLE THROUGH AROUND
SUNRISE MAINLY ACROSS YUMA AND SOUTHERN MARICOPA COUNTIES,
FEEDING OFF A POCKET OF HIGHER ELEVATED INSTABILITY. A REMNANT MCV
IS ALSO MOVING SOUTHWARD THROUGH GILA COUNTY HELPING TO BRING
SOME SHOWER ACTIVITY OVER THE HIGH TERRAIN NORTH OF PHOENIX.
ALTHOUGH THIS ACTIVITY IS EXPECTED TO GRADUALLY DISSIPATE OVER THE
NEXT FEW HOURS, SOME LIGHT TO MODERATE SHOWERS MAY MAKE IT AS FAR
SOUTH AS NORTH PHOENIX.
PREVIOUS DISCUSSION
THE SYNOPTIC PATTERN WILL BECOME EVEN MORE CONDUCIVE FOR ROBUST
THUNDERSTORMS STARTING THIS AFTERNOON AS AT LEAST ONE SHORTWAVE
SHED FROM THE AFOREMENTIONED TEXAS CUTOFF PROGRESSES TOWARDS
SOUTH-CENTRAL ARIZONA DURING PEAK HEATING. WITH CONVECTIVE DEBRIS
AND OUTFLOWS PUMPING ADDITIONAL MOISTURE INTO THE MIDDLE AND LOWER
TROPOSPHERE, TOTAL COLUMN PWATS 1.75-2.00" SHOULD BE COMMON WHILE
BOUNDARY LAYER MIXING RATIOS SETTLE AROUND 12-13 G/KG BY THE
AFTERNOON. THIS MOISTURE PROFILE SHOULD RESULT IN A NEAR EQUAL
MLCAPE/DCAPE BALANCE IN A "SWEET SPOT" OF 1000-1500 J/KG
HISTORICALLY PRESENT DURING BIG MONSOON THUNDERSTORM EVENTS.
CONVECTIVE INHIBITION SHOULD BE NEARLY ABSENT LATE AFTERNOON/EARLY
EVENING, AND WITH UNDERLYING DEEP LAYER ASCENT, IT SHOULD ONLY
TAKE WEAK OUTFLOWS TO INITIATE ADDITIONAL STORMS. INTERSECTING
OUTFLOW BOUNDARIES ARE ALSO LIKELY WITH CONSOLIDATING STORMS OVER
PARTS OF THE CWA RESULTING IN HEAVY RAINFALL AND FLASH FLOODING.
RAINFALL RATES AT LEAST 2-3"/HR APPEAR LIKELY GIVEN THE MOISTURE
PROFILES, AND A FLASH FLOOD WATCH HAS BEEN ISSUED FOR SOUTH-
CENTRAL ARIZONA COUNTIES. HREF AND GLOBAL MODEL OUTPUT SUGGESTS
NORTHERN PINAL AND SW MARICOPA COUNTIES AS THE FOCUS FOR THE
HEAVIEST RAINFALL.
CONSIDERABLE FORECAST UNCERTAINTY STILL EXISTS FRIDAY CONTINGENT
UPON THE STRENGTH AND EXPANSE OF THUNDERSTORMS THIS EVENING AND
TONIGHT. A LARGE SUBSET OF MODELING INDICATES THE ATMOSPHERE
BECOMING COMPLETELY OVERTURNED BY STORMS AND OUTFLOWS FRIDAY
MORNING WITH FORECAST SOUNDINGS DEPICTING A CLASSIC, POST-EVENT
MOIST ADIABATIC PROFILE. SHOULD THIS COME TO FRUITION (BETTER THAN
A 50% CHANCE), CONVECTIVE POTENTIAL THE REMAINDER OF FRIDAY WOULD
BECOME MINIMAL, AT BEST, GIVEN THE COMBINED EXTENSIVE CLOUD COVER
AND POOR LAPSE RATES RESULTING IN ESSENTIALLY NO INSTABILITY. A
SLIGHT ALTERNATIVE OUTCOME IS HINTED AT BY RECENT OPERATIONAL
ECMWF AND NAMNEST OUTPUT WHICH SUGGESTS A WELL DEFINED MCV
JUXTAPOSED WITH A POOL OF HIGHER THETA-E ADVECTING NORTH THROUGH
THE PHOENIX METRO FRIDAY MORNING. WHILE THESE TYPE MODEL FORECASTS
WITH MORNING STORMS FORCED BY AN MCV AND COPIOUS DEEP MOISTURE
ARE COMMON DURING THE MONSOON, THEY ONLY COME TO FRUITION
OCCASIONALLY EVERY SUMMER, BUT WHEN THIS SCENARIO UNFOLDS, VERY
EFFICIENT RAIN RATES AND FLOODING ENSUES. REGARDLESS, THE
STRONGEST MODEL EVIDENCE INDICATES ONLY SMALL POCKETS OF
INSTABILITY REMAINING FRIDAY AFTERNOON WITH REDUCED CHANCES FOR
SHOWERS AND THUNDERSTORMS THROUGH THE REMAINDER OF THE DAY.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
ALTHOUGH SOME UNCERTAINTY REMAINS, GUIDANCE CONTINUES TO TREND
DRIER FOR THIS WEEKEND, PARTICULARLY THE GEFS. THIS DRIER AIR IS
EXPECTED TO ADVECT IN FROM THE SOUTH SOUTHWEST STARTING FRIDAY
MORNING AND CONTINUE THROUGH MOST OF SATURDAY, LOWERING PWATS TO
AS LOW AS 1.4-1.5", BUT THE EURO MAINTAINS A MORE OPTIMISTIC
1.7-1.9". THE EASTERLY WAVE IS ALSO FORECAST TO WEAKEN WHILE IT
BRIEFLY SHIFTS BACK TOWARD CENTRAL TEXAS. THE COMBINATION OF THE
EXPECTED DRYING, VERY LITTLE INSTABILITY, AND WEAKER UPPER LEVEL
SUPPORT IS LIKELY TO LIMIT SHOWER AND THUNDERSTORM POTENTIAL ON
SATURDAY. AS OF NOW, MUCH OF THE LOWER DESERTS SHOULD STAY QUIET
ON SATURDAY, WHILE SCATTERED SHOWERS AND STORMS ARE MUCH MORE
LIKELY OVER THE ARIZONA HIGH TERRAIN. TEMPERATURES WILL BEGIN TO
RECOVER STARTING SATURDAY, BUT DAYTIME HIGHS ARE STILL LIKELY TO
FALL SHORT OF 100 DEGREES IN THE PHOENIX AREA.
STARTING SUNDAY INTO EARLY NEXT WEEK, THE SUBTROPICAL RIDGE IS
LIKELY TO BECOME MORE ELONGATED FROM THE GREAT BASIN TO THE LOWER
MS RIVER VALLEY. THE REMNANTS OF THE EASTERLY WAVE OR EVEN A NEWLY
DEVELOPED DISTURBANCE MAY ALSO BECOME MORE OF A PLAYER FOR
MONSOON ACTIVITY BY AROUND MONDAY OR TUESDAY AS MOISTURE REMAINS
PLENTY ADEQUATE FOR CONVECTION. AN INCREASE IN EASTERLY UPPER
LEVEL WINDS ACROSS TEXAS MAY EVENTUALLY STRETCH INTO THE DESERT
SOUTHWEST BY LATE MONDAY INTO TUESDAY WHICH COULD HELP DRIVE
MONSOON ACTIVITY THROUGHOUT PORTIONS OF THE LOWER DESERTS AGAIN.
NBM POPS STILL FAVOR THE ARIZONA HIGH TERRAIN THROUGH THE PERIOD,
BUT IT SEEMS LIKELY THE LOWER DESERTS WILL SEE ANOTHER DAY OR TWO
OF ACTIVE WEATHER.
FORECAST TEMPERATURES FOR NEXT WEEK SHOW A GRADUAL UPWARD TREND,
DESPITE FAIRLY HIGH MODEL SPREAD. LOWER DESERT DAYTIME HIGHS MAY
AGAIN REACH 100 DEGREES IN THE PHOENIX AREA BY MONDAY AND
EVENTUALLY BACK TO NEAR NORMAL DURING THE LATTER HALF OF NEXT
WEEK. LOCATIONS ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA
ARE LIKELY TO MAINTAIN NEAR NORMAL TEMPERATURES THROUGHOUT NEXT
WEEK.
AVIATION
UPDATED AT 1000Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
A POTENTIAL EXTENDED PERIOD OF ERRATIC WINDS AND VCTS/TSRA IMPACTS
THURSDAY EVENING THROUGH THURSDAY NIGHT WILL BE THE PRIMARY
AVIATION IMPACT AND FORECAST CHALLENGE. AHEAD OF THAT TIME PERIOD,
THERE IS LOW POTENTIAL (10%) FOR SOME HIGH-BASED SHOWERS AND MAYBE
A STORM TO DEVELOP OVER THE NEXT SEVERAL HOURS. TOO LOW FOR
INCLUSION IN THE TAFS. STORMS THIS AFTERNOON ARE FORECAST TO FOCUS
INITIALLY TO THE NORTH AND THEN TO THE SOUTH AND SOUTHEAST, WHICH
MAY LEAD TO PROMINENT OUTFLOWS FROM BOTH DIRECTIONS, WITH A
NORTHERLY OUTFLOW FAVORED FIRST IN THE LATE AFTERNOON. THERE ARE
GOOD CHANCES (40-60%) FOR VCTS/TSRA & VCSH/SHRA AT TERMINALS
HEADING INTO THE LATE EVENING AND OVERNIGHT HOURS THURSDAY. SOME
STORMS MAY PRODUCE VERY HEAVY, BLINDING, RAINFALL. CLOUD BASES
WILL MOSTLY STAY AT OR ABOVE 8-10K FT AGL, BUT THERE IS POTENTIAL
FOR LOWER CLOUD BASES, DOWN TO 6-7K FT AGL. THE DUST POTENTIAL IS
LOW.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION CONCERNS ARE EXPECTED DURING THE NEXT 24 HOURS
UNDER INCREASING MIDLEVEL CLOUDS. SE WINDS WILL BE COMMON AT KIPL,
THOUGH A BRIEF SWITCH OF THE W/SW MAY DEVELOP THIS EVENING.
SOUTHERLY WINDS WILL PREVAIL AT KBLH. A PERIOD OF GUSTS AROUND
20-25 KT MAY DEVELOP AT KBLH LATE THIS MORNING THROUGH THE
AFTERNOON/EARLY EVENING. THERE IS LOW POTENTIAL (10-20%) FOR AN
ISOLATED SHOWER OR STORM THIS AFTERNOON AND EVENING, CONDITIONAL
ON THE EVOLUTION OF DISTURBANCES TO THE EAST OF THE AREA.
FIRE WEATHER
ACTIVE MONSOON WEATHER WITH ELEVATED MOISTURE LEVELS WILL CONTINUE
THROUGH THE REST OF THE WEEK. SHOWER AND THUNDERSTORM CHANCES WILL
INCREASE OVER THE EASTERN DISTRICTS TODAY WITH ONLY ISOLATED
CHANCES OVER THE WESTERN DISTRICTS. LOCALIZED HEAVY RAINFALL IS
EXPECTED TODAY INTO EARLY FRIDAY ACROSS THE EASTERN DISTRICTS WITH
SOME POTENTIAL FOR GUSTY OUTFLOW WINDS LATE THIS AFTERNOON AND
EARLY EVENING. MINRHS WILL BE 35-55% FOR THE EASTERN DISTRICTS
THROUGH SATURDAY TO 20-35% ACROSS THE WESTERN DISTRICTS. OUTSIDE
OF POTENTIAL THUNDERSTORM OUTFLOWS, WINDS FOR THE EASTERN
DISTRICTS WILL TEND TO BE LIGHT AND SOMEWHAT FAVOR DIURNAL TRENDS.
WINDS WILL PREDOMINATELY FAVOR THE SOUTH AND BE BREEZY AT TIMES
ACROSS THE WESTERN DISTRICTS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING UNTIL 8 PM MST THIS EVENING FOR AZZ530-532.
FLOOD WATCH FROM 2 PM MST THIS AFTERNOON THROUGH LATE TONIGHT
FOR AZZ534-537>563.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT THIS EVENING FOR CAZ562-563-
565>567-569-570.
SHORT TERM...KUHLMAN/18
LONG TERM...KUHLMAN
AVIATION...WHITTOCK/BENEDICT
FIRE WEATHER...KUHLMAN
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