306
FXUS65 KPSR 231922
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1222 PM MST WED SEP 23 2026
KEY MESSAGES
- CHANCES FOR SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE
INCREASED TODAY AND THURSDAY WITH THE MOST ACTIVITY FOCUSED OVER
FOOTHILL AND HIGH TERRAIN AREAS.
- ALONG WITH THE CHANCES FOR RAIN, GUSTY STORM DRIVEN OUTFLOW WINDS
WILL BE POSSIBLE TODAY AND THURSDAY, POTENTIALLY LEADING TO PATCHY
BLOWING DUST.
- NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES WILL PERSIST THROUGH
THE WEEKEND BEFORE ADDITIONAL COOLING IS EXPECTED EARLY NEXT WEEK.
SHORT TERM /TODAY THROUGH THURSDAY/
BROAD UPPER LEVEL TROUGH CONTINUES TO BE SEEN TO THE REGION'S
SOUTHWEST, WITH THE CENTER OF THE LOW JUST OFF THE WEST COAST OF THE
BAJA PENINSULA. TO THE EAST RIDGING CAN BE SEEN EXPANDING OVER THE
SOUTHERN PLAINS, WITH THE CORE CENTERED OVER SE TX AND W LA. THE LOW
PRESSURE SYSTEM IS ADVECTING AN INCREASE IN MOISTURE INTO THE DESERT
SW. THE MAIN WEATHER IMPACT FOR LATER THIS EVENING AND TONIGHT WILL
BE THE POTENTIAL FOR ISOLATED TO SCATTED THUNDER STORMS. THE BEST
CHANCES FOR THUNDERSTORMS WILL BE IN THE EASTERN HIGHER TERRAIN
WHERE THE LATEST HREF SHOWS GOOD AGREEMENT IN BETWEEN A 50-70%
CHANCE OF STORM DEVELOPMENT. A LESSER CHANCE FOR THUNDERSTORMS EXIST
FOR THE LOWER DESERTS, AND PHOENIX METRO, BUT NOT IMPOSSIBLE. HREF
SHOWS BETWEEN A 30-50% CHANCE HOWEVER STORM ARE EXPECTED BE BE
ISOLATED IN NATURE.
TONIGHT IS CURRENTLY SHAPING UP TO BE MORE ACTIVE COMPARED TO
THURSDAY NIGHT, WITH DECENT MOISTURE TONIGHT, PWATS NEAR 1.25" AND
1000-700 MB MIXING RATIOS BETWEEN 8-10 G/KG ACROSS SOUTH-CENTRAL
ARIZONA. ADDITIONALLY, GOOD UPPER LEVEL ASCENT EXISTS BETWEEN THE
TROUGH AND THE JET MAX TO OUR NORTH IN THE HIGHER TERRAIN.
FORECASTED MUCAPE VALUES CONTINUE TO BE NEAR 1000 J/KG IN SOUTH-
CENTRAL AZ LOWER DESERTS AND BETWEEN 500-700 J/KG IN THE EASTERN
HIGH TERRAIN REGION. HOWEVER EVEN WITH LOWER CAPE VALUES THE LIFT
JET MAX AND THE NATURAL OROGRAPHIC LIFT WILL PROVIDE THE EXTRA LIFT
NEEDED FOR STORMS TO DEVELOP. CAMS ARE STARTING TO COME INTO BETTER
AGREEMENT IN TERM OF A STRONG OUTFLOW DESCENDING OUT OF THE NE
SWEEPING THROUGH THE LOWER DESERTS, WHERE BLOWING DUST AND
REDUCTIONS INVISIBILITIES WILL BE POSSIBLE. LATER IN THE
EVENING/NIGHT ADDITIONAL CHANCES FOR ISOLATED THUNDERSTORMS ARE
POSSIBLE NEAR SOUTHERN MARICOPA COUNTY, WERE ANOTHER, ALTHOUGH
WEAKER OUTFLOW COULD DEVELOP OUT OF THE SOUTH-SOUTHWEST, AND COLLIDE
WITH THE NORTHEASTERN OUTFLOW WHICH MAY SPARK ADDITIONAL
THUNDERSTORMS INTO THE EARLY OVERNIGHT HOURS OVER THE SOUTHERN
MARICOPA COUNTY AND EVEN AS FAR INTO YUMA, AND LA PAZ COUNTIES.
THURSDAY'S OUTLOOK CONTINUES TO BE QUESTIONABLE, LARGELY BEING
DEPENDENT ON TONIGHT'S ACTIVITY. MOISTURE IS EXPECTED TO DWINDLE
TOMORROW OVER SOUTH-CENTRAL AZ, WITH FORECAST SOUNDINGS SHOWING
PWATS DROPPING TO NEAR 1". INTERESTINGLY THOUGH, MUCAPES ARE
EXPECTED TO BE SLIGHTLY HIGHER, BETWEEN 1000-1250 J/KG THURSDAY
AFTERNOON AS UPPER LEVEL VORTICITY STREAMS DIRECTLY OVER HEAD AS THE
LOW WEAKENS AND PROGRESSES OVER THE DESERT SW. CAMS SHOW LITTLE TO
NO CONVECTION DEVELOPING ACROSS SOUTHERN ARIZONA WITH THE MAJORITY
STAYING TO OUR NORTH. GIVEN THE HIGHER INSTABILITY AND AT LEAST SOME
UPPER LEVEL ASCENT, IT WOULD SEEM WE'D HAVE AT LEAST SIMILAR CHANCES
AS TODAY, BUT NBM POPS REMAIN BELOW 10% FOR THE LOWER DESERTS. IF
TONIGHT'S FORECAST PANS OUT THEN CHANCES FOR THURSDAY WILL LIKELY
CONTINUE TO BE VERY SLIM FOR THE LOWER DESERTS, BUT IF THINGS
STRUGGLE TONIGHT THEN THERE MAY BE HIGH CHANCES FOR DEVELOPMENT
TOMORROW, HOWEVER WITH THE MOISTURE MOVING WESTWARDS ISOLATED
THUNDERSTORMS WILL BE EXPECTED TO MOSTLY BE CONFINED TO THE HIGHER
TERRAIN. IF STORMS ACTUALLY DO GET GOING ON THURSDAY, GUSTY WINDS
AND LOCALIZED HEAVY RAINFALL WILL AGAIN BE POSSIBLE GIVEN THE
EXPECTED DECENT INSTABILITY.
LONG TERM /FRIDAY THROUGH TUESDAY/
BY FRIDAY, THE MAIN UPPER LEVEL TROUGH IS FORECAST TO SHIFT
NORTHEASTWARD OUT OF A OUR REGION LEAVING DRY SOUTHWESTERLY FLOW IN
PLACE. GUIDANCE SHOWS LOW LEVEL MIXING RATIOS QUICKLY DROPPING TO 5-
7 G/KG ACROSS THE LOWER DESERTS TO ONLY 6-8 G/KG OVER THE ARIZONA
HIGH TERRAIN. AS A RESULT, FRIDAY WILL BEGIN ANOTHER DRY PERIOD WITH
ONLY LINGERING CHANCES FOR SOME ISOLATED SHOWERS AND MAYBE A FEW
THUNDERSTORMS OVER THE EASTERN ARIZONA HIGH TERRAIN. TEMPERATURES
ARE FORECAST TO REMAIN QUITE STABLE OVER THE NEXT FEW DAYS WITH
HIGHS RIGHT AROUND TO SLIGHTLY ABOVE NORMAL AND LOWS A FEW DEGREES
ABOVE NORMAL.
WESTERLY DRY FLOW SHOULD PERSIST THROUGH AT LEAST SATURDAY WITH
LARGE SCALE TROUGHING REMAINING TO OUR NORTHWEST WHILE THE
SUBTROPICAL RIDGE SLOWLY SHIFTS SOUTHWESTWARD FROM EAST TEXAS INTO
THE INTERIOR OF MEXICO. THIS SHIFT IN THE RIDGE IS LIKELY TO BRING
HIGHER HEIGHTS TEMPORARILY FOR OUR REGION LATER FRIDAY THROUGH
SATURDAY, SO DAYTIME HIGHS SATURDAY ARE LIKELY TO TOP OUT BETWEEN
100-104 DEGREES (4-6 DEGREES ABOVE NORMAL) UNDER MOSTLY SUNNY SKIES.
FORECAST UNCERTAINTY INCREASES DRAMATICALLY GOING INTO EARLY NEXT
WEEK AS IT WILL LIKELY DEPEND UPON WHAT HAPPENS WITH HURRICANE POLO,
THE POSITIONING OF THE SUBTROPICAL RIDGE, AND AN UPPER LEVEL TROUGH
THAT MAY SWING THROUGH OUR REGION ON OR AROUND NEXT MONDAY. THE
LATEST NHC TRACK FOR POLO HAS IT SLOWLY MAKING ITS WAY WESTWARD OVER
THE NEXT FEW DAYS BEFORE TURNING MORE TO THE NORTH THIS WEEKEND, BUT
STAYING WEST OF SOUTHERN BAJA. THIS TRACK MAY BE ENOUGH TO HELP
ADVECT TROPICAL MOISTURE NORTHWARD AS FAR AS OUR AREA, BUT
UNCERTAINTY REMAINS QUITE HIGH. THERE IS A LOW END POTENTIAL OF
TROPICAL MOISTURE MAKING ITS WAY NORTHWARD INTO OUR AREA JUST BEFORE
THE AFOREMENTIONED TROUGH SWINGS THROUGH OUR REGION AND THIS COULD
LEAD TO CHANCES FOR STRONG TO SEVERE STORMS ALONG WITH HEAVY RAIN
POTENTIAL ON OR AROUND MONDAY. THE MORE LIKELY SCENARIO WOULD
INVOLVE MODEST MOISTURE MAKING ITS WAY INTO OUR AREA, BUT STILL WITH
THE SUPPORT OF THE TROUGH. THE TROUGH MAY STILL BE STRONG ENOUGH TO
SUPPORT SOME STRONG TO SEVERE STORMS DUE TO MUCH HIGHER THAN NORMAL
SHEAR, BUT WITH LESS MOISTURE IT WOULD LOWER THE SEVERE THREAT AS
WELL AS WELL AS THE THREAT FOR HEAVY RAINFALL. AT THIS MOMENT, WE
ARE UNSURE WHICH SOLUTION WILL WIN OUT, BUT WE EXPECT TO HAVE A
BETTER IDEA BY THE WEEKEND.
AVIATION
UPDATED AT 1705Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
VARIABLE WIND DIRECTIONS WITH THE POTENTIAL FOR GUSTY EVENING
OUTFLOWS FOLLOWED BY THE THREAT OF SHRA/TSRA WILL BE MAIN WEATHER
ISSUES THROUGH THURSDAY AFTERNOON UNDER THICK, HIGH CIRRUS CIGS AND
BRIEF PERIODS OF CIGS AS LOW AS 8-10K FT AGL. CONFIDENCE IS GOOD
THAT E/SE WINDS WILL PREVAIL INTO THE MID/LATE AFTERNOON BEFORE
FORECAST CONFIDENCE DECREASES. WIND DIRECTIONS MAY BRIEFLY GO S/SW
LATE AFTERNOON/EARLY EVENING, BUT A 140V240 OSCILLATION MAY BE MORE
ACCURATE.
CONFIDENCE IS INCREASING THAT THUNDERSTORMS OVER THE RIM WILL SEND A
NE OUTFLOW WITH AN ABRUPT WIND SHIFT INTO THE PHX AIRSPACE EARLY/MID
EVENING (02-05Z TIMING) WITH GUSTS BRIEFLY REACHING 30-35KT. A FEW
SHRA/TSRA MAY IMPACT THE AREA, AND HAVE MAINTAINED A PROB30 MENTION
OF TS, THOUGH CONFIDENCE IN DEVELOPMENT AND COVERAGE IN THE PHX
METRO IS VERY LOW. CONFIDENCE IS BETTER THAT ONCE ACTIVITY CLEARS
THE METRO LATER THIS EVENING, EAST WINDS WILL HOLD OVER THE AREA
THROUGH MUCH OF THE DAY THURSDAY.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO WEATHER ISSUES WILL EXIST THROUGH THURSDAY AFTERNOON UNDER
INCREASING HIGH CIRRUS DECKS. CONFIDENCE IN A SPECIFIC WIND
DIRECTION AT ANY GIVEN TIME IS LOW GIVEN THE WEAK PRESSURE GRADIENT.
EXTENDED PERIODS OF LIGHT AND VARIABLE WINDS WILL BE COMMON.
FIRE WEATHER
TODAY INTO TONIGHT WILL BRING MODEST CHANCES 30-50% FOR SHOWERS
AND THUNDERSTORMS, FOCUSED OVER THE EASTERN DISTRICTS, WHILE THE
WESTERN DISTRICTS SHOULD MOSTLY REMAIN DRY. GUSTY OUTFLOW WINDS
WITH ABRUPT WIND SHIFTS ARE EXPECTED DURING THE FIRST PART OF THE
EVENING, PREDOMINATELY OUT OF THE NE. MINRHS BETWEEN 15-20% RANGE
TODAY FOR THE WESTERN DISTRICTS AND 20-25% THURSDAY, WHILE THE
EASTERN DISTRICTS ARE BETWEEN 25-40% TODAY AND THURSDAY. WINDS
ACROSS EASTERN DISTRICTS WILL GENERALLY MAINTAIN A EAST SOUTHEAST
DIRECTION, FREQUENTLY BECOMING GUSTY WHILE LIGHTER, DIURNALLY
DRIVEN WINDS WILL PERSIST IN WESTERN DISTRICTS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...RYAN
LONG TERM...KUHLMAN
AVIATION...18
FIRE WEATHER...KUHLMAN/RYAN
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