414
FXUS65 KPSR 231706
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1005 AM MST WED SEP 23 2026
UPDATE
UPDATED AVIATION
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 TROUGHING REMAINS POSITIONED OVER THE SOUTHWESTERN
U.S. WITH SEVERAL SMALLER SCALE DISTURBANCES WITHIN THE LARGER SCALE
TROUGH AND ABUNDANT MOISTURE FROM EASTERN ARIZONA THROUGH NEW
MEXICO. THE MAIN FORECAST CONCERNS FOR TODAY AND THURSDAY WILL BE
THE POTENTIAL FOR ISOLATED TO SCATTERED THUNDERSTORMS WHICH WILL BE
CAPABLE OF PRODUCING STRONG DOWNDRAFT AND OUTFLOW WINDS, ALONG WITH
VERY LOCALIZED HEAVY RAINFALL. CURRENT OBJECTIVE ANALYSIS SHOWS
LOWER LEVEL EASTERLY FLOW INCREASING ACROSS SOUTHEAST INTO SOUTH-
CENTRAL ARIZONA SPREADING MOISTURE WESTWARD WHILE WATER VAPOR
IMAGERY SHOWS MULTIPLE DISTURBANCES SOUTH AND EAST OF OUR AREA.
FOR THE REST OF THIS MORNING AND INTO THE AFTERNOON, THE EASTERLY
FLOW IS EXPECTED TO INCREASE MOISTURE LEVELS WITH LOW LEVEL MIXING
RATIOS OF 8-10 G/KG SHIFTING INTO SOUTH-CENTRAL ARIZONA. THE
FORECAST FOR THIS AFTERNOON THROUGH EARLY TONIGHT REMAINS SOMEWHAT
UNCERTAIN AS THE MAIN CONVECTIVE POTENTIAL SHOULD BE FOCUSED WELL TO
OUR EAST IN NEW MEXICO ASSOCIATED WITH DISTURBANCE MOVING NORTH
NORTHEASTWARD THROUGH THE STATE. FOR OUR AREA, WE WILL FALL UNDER
LARGER SCALE ASCENT ASSOCIATED WITH THE TROUGH AND A JET MAX TO OUR
NORTH LEAVING THE HIGHER TERRAIN AS THE BEST AREA OF FOCUS FOR
SHOWER AND THUNDERSTORM DEVELOPMENT THIS AFTERNOON.
GIVEN THE AVAILABLE MOISTURE AND MODEST HEATING TODAY UNDER PARTLY
SUNNY SKIES, FORECAST MUCAPE SHOULD REACH 1000 J/KG OVER THE SOUTH-
CENTRAL ARIZONA LOWER DESERTS TO 500-750 J/KG TO OUR NORTH AND EAST.
HI-RES CAMS HAVE BEEN INCONSISTENT WITH THE AMOUNT OF CONVECTION FOR
TODAY INTO TONIGHT, BUT THEY HAVE MOSTLY KEPT WITH INITIATION OVER
THE HIGHER TERRAIN LATER THIS AFTERNOON. GIVEN A SOMEWHAT DRY
ENVIRONMENT IN THE LOWER DESERTS, DCAPES OF 1200-1500 J/KG ARE
EXPECTED WHICH SHOULD LEAD TO HIGH CHANCES OF ONE MORE MORE OUTFLOWS
BEING GENERATED. EVEN THOUGH THE CAMS HAVE BEEN FAIRLY INCONSISTENT,
STORM OUTFLOWS ARE EXPECTED WHICH IN TURN MAY BE ENOUGH TO INITIATE
FURTHER STORM DEVELOPMENT OVER THE LOWER DESERTS THIS EVENING. THESE
CHANCES (20-30%) WILL BE CONTINGENT UPON AT LEAST ONE FAIRLY STRONG
OUTFLOW, OR EVEN COLLIDING WEAKER/SMALLER OUTFLOWS. SOME ITERATIONS
OF THE CAMS HAVE EVEN SUGGESTED A LARGE STRONG OUTFLOW PROGRESSING
AS FAR WEST AS LA PAZ AND YUMA COUNTIES, SPARKING BRIEF SHOWERS AND
STORMS LATE IN THE EVENING TO AS LATE AS 2 AM TONIGHT.
THURSDAY'S FORECAST LOOKS EVEN MURKIER AS MOISTURE IS EXPECTED TO
CONTINUE TO SPREAD WESTWARD THROUGH SOUTHWEST ARIZONA INTO SOUTHEAST
CALIFORNIA, WHILE THE UPPER LEVEL ASCENT IS LIKELY TO REMAIN
POSITIONED OVER THE EASTERN HALF OF ARIZONA. HREF SHOWS EVEN HIGHER
MUCAPES FOR THURSDAY WITH THE BULK OF AREA REACHING 1000-1250 J/KG
DURING THE AFTERNOON HOURS WHILE AN UPPER LEVEL SHORTWAVE IS
FORECAST TO MOVE THROUGH SOUTHEAST ARIZONA. HOWEVER, THERE SEEMS TO
BE EVEN MORE UNCERTAINTY WITHIN THE MODELS AS THE 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 ARE MOSTLY BELOW 10% FOR THE
LOWER DESERTS. FORECAST SOUNDINGS DO STILL SHOW WEAK TO POSSIBLY
MODEST CONVECTIVE INHIBITION OVER THE LOWER DESERTS, SO LIKE TODAY
WE'D MOSTLY HAVE TO RELY ON SOME SORT OF STRONG OUTFLOW OR OUTFLOW
COLLISIONS FOR STORMS TO DEVELOP OVER THE LOWER DESERTS. NEEDLESS TO
SAY, UNCERTAINTY REMAINS QUITE HIGH FOR THURSDAY'S RAIN CHANCES. IF
STORMS ACTUALLY DO GET GOING ON THURSDAY, GUSTY WINDS AND LOCALIZED
HEAVY RAINFALL WILL AGAIN BE POSSIBLE GIVEN THE EXPECTED DECENT
INSTABILITY AND MODEST DCAPE.
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.
MINRHS WILL FALL INTO A 15-20% RANGE TODAY FOR THE WESTERN DISTRICTS
AND 20-25% THURSDAY, WHILE THE EASTERN DISTRICTS WILL FALL TO 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...KUHLMAN
LONG TERM...KUHLMAN
AVIATION...18
FIRE WEATHER...KUHLMAN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page