585
FXUS65 KPSR 111157
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
457 AM MST THU AUG 11 2022
UPDATE
UPDATED AVIATION DISCUSSION.
SYNOPSIS
TODAY SHOULD BRING A BRIEF BREAK FROM FAIRLY WIDESPREAD MONSOON
STORMS WITH HIGH TEMPERATURES REMAINING NEAR NORMAL. CHANCES FOR
SHOWERS AND THUNDERSTORMS ARE THEN LIKELY TO PICK BACK UP STARTING
FRIDAY AND LAST THROUGH AT LEAST THE WEEKEND WITH HEAVY RAINFALL,
LOCALIZED FLASH FLOODING, GUSTY WINDS, AND LOCALIZED BLOWING DUST
POSSIBLE. TEMPERATURES ARE THEN EXPECTED TO DROP TO SLIGHTLY
BELOW NORMAL READINGS OVER THE WEEKEND INTO EARLY NEXT WEEK.
DISCUSSION
YESTERDAY WAS A FAIRLY ACTIVE MONSOON STORM DAY, PARTICULARLY
ACROSS WESTERN AND CENTRAL ARIZONA. THE LARGE SCALE WEATHER
PATTERN WILL CHANGE VERY LITTLE THROUGH AT LEAST THE WEEKEND WITH
A STRONG SUB-TROPICAL HIGH CENTERED OVER COLORADO PROVIDING
PERSISTENT SOUTHEASTERLY MOIST FLOW INTO OUR REGION. GIVEN THE
ACTIVE DAY YESTERDAY, THE ATMOSPHERE WILL OVERALL BE LESS
CONDUCIVE FOR STORM ACTIVITY TODAY. CURRENT IR SATELLITE IMAGERY
SHOWS LINGERING DEBRIS CLOUD FROM EARLIER STORM ACTIVITY ACROSS
SOUTHERN ARIZONA AND A WEAKENING STORM COMPLEX OVER NORTHERN
MEXICO. A REMNANT MCV IS ALSO CURRENTLY DRIFTING SLOWLY
NORTHWESTWARD ACROSS THE PHOENIX AREA WITH HI-RES GUIDANCE SHOWING
THIS FEATURE LIKELY PROVIDING A FOCUS MECHANISM FOR STORMS
NORTHWEST OF OUR AREA LATER TODAY, BUT KEEPING FAIRLY SUBSIDENT
FLOW OVER SOUTH-CENTRAL ARIZONA. 00Z HREF AND LATEST HRRR AGREES
TODAY SHOULD BE AN OVERALL DOWN MONSOON DAY WITH A FEW ISOLATED
STORMS POSSIBLE OVER THE WESTERN DESERTS AND OVER THE EASTERN
ARIZONA HIGH TERRAIN, BUT LIKELY NOT MUCH OF ANYTHING IN THE
PHOENIX AREA. LOCALIZED MODERATE HEATRISK TODAY SHOULD BE THE
BIGGEST IMPACT WITH TEMPERATURES NEAR NORMALS, BUT ELEVATED
HUMIDITIES MAKING IT FEEL QUITE UNCOMFORTABLE. OVERNIGHT
TEMPERATURES WILL ALSO NOT RECOVER ALL THAT WELL THROUGH FRIDAY
MORNING WITH LOWS MOSTLY IN A 83-88 DEGREE RANGE OVER THE LOWER
DESERTS.
STARTING FRIDAY, GUIDANCE IS SUGGESTING A RETURN TO MORE FAVORABLE
MONSOON STORM CONDITIONS WITH INCREASED INSTABILITY. THERE ARE
ALSO SIGNS OF ANOTHER POTENTIAL INVERTED TROUGH TRACKING INTO
SOUTHERN ARIZONA PROVIDING AREAS OF ASCENT ON FRIDAY, WHILE OUR
AREA MAY ALSO SEE MORE BROAD SCALE UPPER LEVEL ASCENT AS MODELS
SHOW AT LEAST WESTERN ARIZONA FALLING WITHIN THE RIGHT ENTRANCE
REGION OF A JET STREAK POSITIONED TO OUR NORTHWEST. NBM POPS
INCREASE TO ROUGHLY 30-40% OVER THE MAJORITY OF THE LOWER DESERTS
STARTING FRIDAY TO 50-70% OVER HIGHER TERRAIN AREAS OF EASTERN
ARIZONA, LASTING THROUGH THE WEEKEND AREAWIDE. MOISTURE LEVELS
THROUGH THE PERIOD WILL REMAIN PLENTY SUFFICIENT FOR HEAVY
RAINFALL POTENTIAL, BUT LIKELY NOT TOO EXCESSIVE TO WHERE WE LOSE
SUFFICIENT INSTABILITY FOR STRONG THUNDERSTORMS. POTENTIAL IMPACTS
STARTING FRIDAY WILL INCLUDE STRONG WINDS, BLOWING DUST, HEAVY
RAINFALL, AND LOCALIZED FLOODING. ANY OF THOSE DAYS COULD BE QUITE
ACTIVE, BUT IF ONE DAY SEES WIDESPREAD STORMS, THE SUBSEQUENT DAY
IS LIKELY TO BE FAIRLY QUIET AS THE ATMOSPHERE WILL NEED TIME TO
DESTABILIZE. RELATIVELY WEAK WIND SHEAR IS EXPECTED THROUGH THE
PERIOD, SO INDIVIDUAL STORMS ARE NOT LIKELY TO MAINTAIN THEMSELVES
FOR LONG, BUT CLUSTERS OF STORMS FORMING OVER HIGHER TERRAIN
AREAS MAY LEAD TO ADDITIONAL STORM DEVELOPMENT INTO THE LOWER
DESERTS ALONG A DEEP OUTFLOW OR COLLIDING OUTFLOWS. SHOWERS AND
STORM DEVELOPMENT WILL ALSO BE POSSIBLE WITH ANY REMNANT MCVS OR
INVERTED TROUGHS THAT TRAVERSE THE AREA.
AT SOME POINT EARLY NEXT WEEK, THE PATTERN WILL BEGIN TO SHIFT
WITH THE SUB-TROPICAL HIGH TO OUR NORTHEAST WEAKENING, WHILE A
WEAK TROUGH POSSIBLY SETS UP OFF THE SOUTHERN CALIFORNIA COAST.
THIS SCENARIO MAY NOT BRING MUCH OF A CHANGE TO OUR AREA WITH
MODELS CONTINUING TO SHOW ADEQUATE MOISTURE LEVELS FOR STORMS, BUT
OVERALL FORECAST CONFIDENCE IS LOW DUE TO THE CHANGE IN THE UPPER
LEVEL PATTERN AND SOME MODEL DIFFERENCES. TEMPERATURES ARE
EXPECTED TO COOL OFF SLIGHTLY AT SOME POINT OVER THE WEEKEND INTO
EARLY NEXT WEEK WITH FORECAST HIGHS CLOSER TO 100 DEGREES DUE TO
ANTICIPATED MORE ACTIVE MONSOON CONDITIONS.
AVIATION
UPDATED 1156Z.
SOUTH-CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
LIGHT WINDS FAVORING THE E TO SE WILL CONTINUE THROUGH THE MORNING
BEFORE SWITCHING AROUND TO THE WEST BY EARLY THIS AFTERNOON.
ANOTHER DAY OF STORMS BOTH N AND SE OF THE METRO WILL LIKELY CAUSE
OUTFLOW BOUNDARIES TO MAKE A RUN FOR THE AREA IN THE EARLY
EVENING. AT THIS TIME, THE SE OUTFLOW LOOKS MORE DOMINANT - SO IT
IS REFLECTED IN THE TAF AS SUCH; PROBABILITY OF WIND GUSTS
EXCEEDING 30KT IS ONLY AROUND 30% IN THE EARLY EVENING. ANY STRONG
OUTFLOWS WILL POSE THE POTENTIAL FOR BLOWING DUST, WHICH WILL IN
RETURN LOWER VISIBILITY. THERE WILL BE A 30% CHANCE FOR ISOLATED
SHOWER/THUNDERSTORM DEVELOPMENT AS OUTFLOWS APPROACH THE VALLEY.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
WINDS WILL GENERALLY FAVOR A SOUTHERLY COMPONENT THROUGH THE
PERIOD WITH DIRECTIONS BECOMING VARIABLE AT TIMES. CHANCES FOR
SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING ARE AROUND
20% OR LESS AT THE TERMINALS. ANY THUNDERSTORM THAT MAY DEVELOP
WOULD BE CAPABLE OF GUSTY ERRATIC WINDS, BLOWING DUST, AND LOCALLY
HEAVY RAINFALL.
FIRE WEATHER
AMPLE MONSOONAL MOISTURE IS EXPECTED TO PERSIST THROUGH AT LEAST
THE FIRST HALF OF NEXT WEEK KEEPING THE FIRE DANGER THREAT LOW.
THIS MOIST AIRMASS WILL CONTINUE TO YIELD ELEVATED HUMIDITIES
WITH AFTERNOON MINIMUM RH VALUES MOSTLY IN A 30-35% RANGE,
LOCALLY HIGHER, AND GOOD OVERNIGHT RECOVERY. CHANCES FOR WETTING
RAINS WILL CONTINUE FOR MOST AREAS ALMOST DAILY. WINDS FOR THE
MOST PART WILL REMAIN LIGHT, WITH THE EXCEPTION OF THUNDERSTORM
OUTFLOWS GENERATING STRONGER GUSTS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
DISCUSSION...KUHLMAN
AVIATION...SMITH/HEIL
FIRE WEATHER...KUHLMAN
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