581
FXUS65 KPSR 251018
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
318 AM MST FRI SEP 25 2026
KEY MESSAGES
- TODAY WILL MARK THE START OF A SHORT DRYING TREND WITH A RETURN
TO OVERALL SUNNY SKIES AND TEMPERATURES HOLDING AROUND, TO
SLIGHTLY ABOVE NORMAL THROUGH THE WEEKEND.
- STARTING SUNDAY, MOISTURE WILL SURGE BACK INTO THE REGION WITH
CLOUDY SKIES AND EVENTUAL CHANCES FOR LIGHT RAIN LATER IN THE
DAY.
- MONDAY AND TUESDAY MAY BRING GOOD CHANCES FOR RAIN AND POSSIBLY
SOME STRONG THUNDERSTORMS. HEAVY RAINFALL WILL ALSO BE
POSSIBLE, PARTICULARLY ACROSS THE ARIZONA HIGH TERRAIN.
- TEMPERATURES WILL COOL TO BELOW NORMAL DURING THE FIRST HALF OF
NEXT WEEK WITH HIGHS FROM THE MID EIGHTIES TO THE MID NINETIES.
SHORT TERM /TODAY THROUGH SATURDAY/
A SHORTWAVE TROUGH WITH A WELL-DEFINED VORT CENTER CURRENTLY
MOVING NORTHEASTWARD THROUGH SOUTH-CENTRAL ARIZONA BROUGHT
SHOWERS AND THUNDERSTORMS SINCE LAST EVENING, BUT IT HAS FINALLY
COMING TO AN END. AS THE DISTURBANCE CONTINUES TO MOVE TO THE
NORTHEAST THIS MORNING, WE MAY SEE SOME LINGERING SHOWERS OVER THE
EASTERN ARIZONA HIGH TERRAIN BEFORE COMING TO AN END NEAR OR JUST
AFTER SUNRISE. DRIER AIR WILL THEN GRADUALLY MOVE INTO THE REGION
FROM THE SOUTHWEST LATER TODAY THROUGH SATURDAY RESULTING IN
OVERALL CLEAR SKIES. EXPECT PLENTY OF LOW LEVEL MOISTURE TO STICK
AROUND THROUGH SATURDAY MORNING BEFORE THE DRIER AIR FINALLY MIXES
DOWN TO THE SURFACE SATURDAY AFTERNOON. TEMPERATURES WILL ALSO
WARM UP A BIT WITH THE LACK OF CLOUDS, PUSHING DAYTIME HIGHS BACK
INTO NORMAL RANGE FOR THE PHOENIX AREA TO SLIGHTLY ABOVE NORMAL
ACROSS THE WESTERN DESERTS.
LONG TERM /SUNDAY THROUGH THURSDAY/
A SIGNIFICANT WEATHER EVENT COULD BE SHAPING UP FOR NEXT MONDAY
INTO TUESDAY AS MODELS ARE BEGINNING TO COME TO A BETTER
CONSENSUS FOR A SEASONABLY STRONG UPPER LEVEL TROUGH MOVING
THROUGH OUR REGION. THE BIGGEST UNCERTAINTY STILL INVOLVES HOW
MUCH MOISTURE WILL BE AVAILABLE WHEN THE TROUGH DOES MOVE THROUGH,
BUT IT IS LOOKING MORE OPTIMISTIC COMPARED TO LAST NIGHT.
THIS NEXT EVENT IS EXPECTED TO START WITH STRONG UPPER LEVEL
MOISTURE ADVECTION FROM THE SOUTHWEST WHICH WILL ACTUALLY COME
FROM THE REMNANTS OF THE DECAYING TROPICAL SYSTEM ODALYS. ODALYS
IS FORECAST TO DRIFT NORTHWARD OVER THE NEXT DAY OR TWO BEFORE
GETTING ABSORBED INTO THE WESTERLIES AS A TROUGH DIGS
SOUTHEASTWARD OFF THE COAST OF CALIFORNIA. WE CAN ANTICIPATE
PLENTY OF HIGHER LEVEL MOISTURE AND CLOUDS OVERSPREADING OUR AREA
BEGINNING SATURDAY EVENING AND CONTINUING THROUGH MUCH OF SUNDAY.
THIS MOISTURE FETCH IS LIKELY TO BE VERY CONSISTENT FOR 18-24
HOURS WITH GRADUAL TOP-DOWN MOISTENING OF THE ATMOSPHERE. BY
SUNDAY MID TO LATE MORNING, SOME AREAS MAY START TO SEE SOME
SPRINKLES, OR EVEN VERY LIGHT RAIN, BUT NO MEASURABLE RAINFALL. IT
WOULD NOT BE SURPRISING TO SEE A FAIRLY NARROW BAND OF LIGHT RAIN
DEVELOPING BY SUNDAY EVENING SOMEWHERE ACROSS THE AREA, BUT
AMOUNTS ARE EXPECTED TO REMAIN VERY LIGHT.
ALSO STARTING SUNDAY, HURRICANE POLO IS FORECAST TO APPROACH
SOUTHERN BAJA BEFORE EVENTUALLY TRACKING TO THE NORTHEAST ACROSS
BAJA AND THE GULF OF CALIFORNIA MOST LIKELY LATER ON MONDAY. THE
LATEST NHC TRACK OF POLO KEEPS IT WELL TO OUR SOUTH AS IT IS
EXPECTED TO FALL APART QUICKLY AS IT MOVES ONSHORE INTO SOUTHERN
SONORA MEXICO. WE ARE NOT WORRIED ABOUT ANY DIRECT IMPACTS FROM
POLO, BUT IT IS BECOMING INCREASINGLY MORE LIKELY IT WILL HELP
DIRECT ADDITIONAL MOISTURE NORTHWARD INTO OUR REGION, SPECIFICALLY
IN THE LOW TO MID LEVELS. THIS MOISTURE WILL BE NECESSARY FOR ANY
DECENT RAINFALL TO OCCUR EARLY NEXT WEEK, SO ANY BIG DEVIATIONS IN
THE FORECAST MOISTURE WILL AFFECT OUR RAIN CHANCES FOR MONDAY AND
TUESDAY.
ALTHOUGH THE DETAILS ARE EXPECTED TO CHANGE, FORECAST CONFIDENCE
FOR A DECENT WEATHER/RAIN EVENT CONTINUES TO INCREASE. AS THE BULK
OF THE UPPER LEVEL MOISTURE FROM THE REMNANTS OF ODALYS MOSTLY
PUSHES INTO NEW MEXICO LATER ON SUNDAY, WE SHOULD BEGIN TO SEE
MOISTURE STREAM OUT OF THE SOUTH SOUTHWEST FROM POLO BY MONDAY
MORNING. THE BEST MOISTURE IS EXPECTED TO BYPASS OUR REGION TO THE
SOUTHEAST, BUT WE STILL SHOULD SEE GOOD MOISTURE WORKING INTO
MOST OF ARIZONA EARLY ON MONDAY, RIGHT AHEAD OF THE APPROACHING
UPPER LEVEL TROUGH. ENSEMBLE MEAN PWATS OF 200% OF NORMAL ARE
SHOWN FOR THE EASTERN 2/3RDS OF ARIZONA ON MONDAY WITH THE BULK OF
THIS MOISTURE FALLING IN THE LOW AND MID LEVELS, JUST WHERE IT
WOULD BE NEEDED FOR A DECENT RAIN EVENT.
THE UPPER LEVEL TROUGH WILL PLAY A VERY IMPORTANT ROLE EARLY NEXT
WEEK AS IT LOOKS LIKELY TO PROVIDE STRONG FORCING ON MONDAY AND
TUESDAY. UPPER LEVEL ASCENT IS EXPECTED TO BE QUITE GOOD, ALONG
WITH VERY GOOD 30-45 KTS OF SOUTHWESTERLY UPSLOPE FORCING WITHIN
THE MID LEVELS. IT IS STILL TOO EARLY TO HAVE A GREAT IDEA ON THE
DETAILS OF THE EVOLUTION OF THE RAINFALL, BUT IT COULD START IN
EARNEST BY MONDAY MORNING. NBM POPS INCREASE AREAWIDE BY MONDAY
MORNING WITH 30-50% CHANCES ACROSS THE WESTERN DESERTS TO 50-75%
FROM PHOENIX AND NORTH AND EAST OF PHOENIX. THESE POPS BASICALLY
HOLD THROUGH MONDAY NIGHT BEFORE GRADUALLY TAPERING OFF FROM WEST
TO EAST ON TUESDAY. WE MAY SEE FAIRLY STEADY UPSLOPE SHOWERS AND
ISOLATED THUNDERSTORMS ACROSS SOUTH-CENTRAL AND EASTERN ARIZONA
MONDAY THROUGH EARLY TUESDAY.
WE ARE CURRENTLY LOOKING AT THREE POSSIBLE SCENARIOS FOR EARLY
NEXT WEEK. FIRST, AND THE MOST LIKELY OUTCOME (~60% CHANCE), IS
FOR A MODESTLY STRONG UPPER LEVEL TROUGH TO PUSH THROUGH MONDAY
INTO TUESDAY WITH VERY ADEQUATE, BUT NOT TROPICAL LEVEL MOISTURE
GETTING PULLED INTO OUR AREA RIGHT AHEAD OF THE PASSING TROUGH.
THIS SCENARIO WOULD SUPPORT WIDESPREAD RAINFALL AMOUNTS OF
0.10-0.30" OVER THE LOWER DESERTS TO 0.5-1.0" OVER THE HIGH
TERRAIN NORTH AND EAST OF PHOENIX. THIS SHOULD ALSO INVOLVE A
PERIOD OF STRONG THUNDERSTORMS DUE TO QUITE GOOD WIND SHEAR.
SECOND, (~20% CHANCE) WOULD KEEP THE BEST MOISTURE TO OUR SOUTH
AND/OR A MUCH WEAKER AND FASTER TROUGH. IN THIS SCENARIO, WE WOULD
EXPECT MUCH MORE SCATTERED RAINFALL WITH LOWER DESERT AMOUNTS
UNDER A 0.25" AND HIGHER TERRAIN AMOUNTS MORE LIKE 0.25-0.75". AT
THE OTHER END OF THE SPECTRUM (~20% CHANCE) WOULD LEAVE US WITH
THE UPPER END OF POTENTIAL MOISTURE COMBINING WITH A STRONGER AND
SLOWER TROUGH. THIS WOULD BRING A LONGER RAIN EVENT WITH LOWER
DESERT RAIN AMOUNTS AVERAGING FROM 0.2-0.5" OVER THE WESTERN
DESERTS TO 0.75-1.50" FOR THE SOUTH-CENTRAL ARIZONA LOWER DESERTS.
AS MUCH AS 2-3" WOULD ALSO BE VERY POSSIBLE OVER THE HIGH TERRAIN
NORTH AND EAST OF PHOENIX. THIS STRONGER EVENT IS ALSO LIKELY TO
INVOLVE A PERIOD OF STRONG TO SEVERE STORMS.
IT WILL BE ANOTHER DAY OR TWO UNTIL WE HAVE A GOOD IDEA ON THE
EXPECTED IMPACTS FOR THIS UPCOMING EVENT, BUT AS STATED ABOVE
THERE IS AT LEAST SOME POSSIBILITY OF A HIGH IMPACT EVENT. WE
WILL CONTINUE TO MONITOR THE MODEL TRENDS AND PROVIDE THE LATEST
UPDATES WITH THIS UPCOMING WEATHER EVENT.
TEMPERATURES ARE EXPECTED TO TAKE A BIG DIP EARLY NEXT WEEK WITH
LOWER DESERT HIGHS FALLING TO AS LOW AS THE MID 80S IN THE
PHOENIX AREA TO THE LOW TO MID 90S ACROSS THE WESTERN DESERTS.
ONCE THE WEATHER SYSTEM EJECTS TO THE EAST BY NEXT WEDNESDAY, WE
SHOULD FALL BACK INTO A DRIER AND WARMER PATTERN.
AVIATION
UPDATED AT 0537Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
ISOLATED TO SCATTERED SHOWERS AND STORMS SHOULD MOSTLY FOCUS
AROUND EASTERN PORTIONS OF PHOENIX TONIGHT, WHILE SLOWLY MOVING
ENE. ACTIVITY SHOULD THEN COME TO AN END BY 12Z FRIDAY MORNING. A
LIGHT W-N WIND IS FAVORED AWAY FROM THE ACTIVITY AND MORE
VARIABLE TO LIGHT E-SE IN THE VICINITY OF THE ACTIVITY, BUT
OVERALL WIND DIRECTION FORECAST CONFIDENCE IS LOW. ONCE ACTIVITY
MOVES EAST OF ALL TERMINALS A PREVAILING LIGHT E WIND SHOULD
DEVELOP AT ALL TERMINALS. THE REST OF FRIDAY WILL FEATURE MORE
TYPICAL DIURNAL TENDENCIES WITH AN AFTERNOON W-SW SHIFT. WIND
SPEEDS THROUGH THE DAY FRIDAY SHOULD REMAIN LIGHT (AOB 8 KT).
BRIEF CIGS DOWN TO 6-7K FT AGL ARE POSSIBLE IN SHRA/TSRA, WITH MID
AND HIGH CIGS MORE COMMON THROUGH THE NIGHT. FEW TO SCT CUMULUS
AROUND 7K FT AGL IS EXPECTED FRIDAY AFTERNOON.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO AVIATION WEATHER IMPACT ARE EXPECTED DURING THE NEXT 24 HOURS.
BOTH TERMINALS WILL EXPERIENCE LIGHT WINDS THROUGHOUT THE TAF
PERIOD WITH PERIODS OF CALM AND LIGHT VRB. WIND DIRECTIONS WILL
MOSTLY FAVOR A SOUTHEASTERLY COMPONENT AT KIPL AND SSW-SSE AT
KBLH. FEW TO SCT SKIES WILL BE PRESENT OVER THE REGION THROUGH
EARLY TONIGHT, FOLLOWED BY CLEARER SKIES HEADING INTO FRIDAY. HIGH
CIRRUS WILL THEN SPREAD BACK OVER THE AREA FRIDAY EVENING.
FIRE WEATHER
LINGERING MORNING SHOWERS ACROSS EASTERN ARIZONA AS WELL AS A
SLIGHT CHANCE OF AN ISOLATED SHOWER OR WEAK STORM IN THE
AFTERNOON ARE EXPECTED TODAY. MUCH DRIER AIR WILL SETTLE INTO THE
REGION LATER TODAY AND LAST THROUGH SATURDAY WITH TEMPERATURES
RETURNING TO AROUND NORMAL. MINRHS TODAY WILL BOTTOM OUT BETWEEN
25-45% ACROSS THE EASTERN DISTRICTS AND 15-25% ACROSS THE WESTERN
DISTRICTS BEFORE DROPPING FURTHER TO 15-25% IN MOST AREAS ON
SATURDAY. WINDS WILL GENERALLY FOLLOW THE TYPICAL DIURNAL
TENDENCIES WITH LIMITED TO NO AFTERNOON GUSTS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...KUHLMAN
LONG TERM...KUHLMAN
AVIATION...BENEDICT
FIRE WEATHER...KUHLMAN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page