717
FXUS65 KPSR 131011
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
311 AM MST SUN SEP 13 2026
KEY MESSAGES
- ABUNDANT MOISTURE WILL REMAIN SITUATED ACROSS THE EASTERN HALF
OF ARIZONA PROVIDING ENHANCED CHANCES FOR SHOWERS AND
THUNDERSTORMS THROUGH THE MIDDLE PART OF THE WEEK, ESPECIALLY
OVER MOUNTAIN LOCATIONS.
- ALTHOUGH UNCERTAINTY REMAINS, THERE WILL BE POTENTIAL FOR SOME
STORMS TO PRODUCE STRONG WINDS AND HEAVY RAINFALL OVER THE NEXT
SEVERAL DAYS.
- NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES ARE EXPECTED
THROUGHOUT ALL OF THE COMING WEEK.
SHORT TERM /TODAY THROUGH MONDAY/
THE MAIN FORECAST CONCERN EARLY THIS WEEK (AND EVEN THROUGH THE
MIDDLE OF THE WEEK) WILL CONTINUE TO BE THE CONDITIONAL
PROBABILITIES OF THUNDERSTORMS ACROSS THE AREA, SOME OF WHICH
COULD PRODUCE LOCALIZED STRONG WINDS, BLOWING DUST, AND HEAVY
RAINFALL. THE SUBTROPICAL RIDGE CONTINUES TO GIVE WAY TO BROAD
UPPER LEVEL TROUGHING BUILDING IN ACROSS THE NORTHWESTERN U.S. BY
MONDAY, THE RIDGE CENTER IS FORECAST TO BE POSITIONED OVER THE
SOUTHEASTERN U.S. WITH THE BROAD TROUGHING FILTERING MORE INTO OUR
REGION AND LIKELY STAYING THERE FOR MUCH OF THE WEEK. AT LEAST
THE EASTERN HALF OF ARIZONA WILL REMAIN WELL POSITIONED MUCH OF
THIS WEEK FOR PERIODIC INFLUXES OF MOISTURE OUT OF NORTHERN MEXICO
AND OFF THE GULF OF CALIFORNIA. MOISTURE LEVELS ARE EXPECTED TO
REMAIN VERY ADEQUATE FOR SHOWER AND THUNDERSTORM POTENTIAL OVER
THE NEXT SEVERAL DAYS WITH THE MAIN LIMITING FACTORS BEING THE
OVERALL WEAK UPPER LEVEL SUPPORT AND WEAK TO MODERATE CONVECTIVE
INHIBITION.
SATURDAY'S SHOWERS AND STORMS OVERACHIEVED COMPARED TO FORECAST
GUIDANCE, JUST LIKE FRIDAY. MODELS HAVE HAD A DIFFICULT TIME WITH
DEPICTING STORM POTENTIAL IN THIS SOMEWHAT CONDITIONAL ENVIRONMENT
AND UNDER A SOUTHWESTERLY STEERING FLOW. UNFORTUNATELY, THIS IS
LIKELY TO BE THE CASE FOR TODAY AND PROBABLY MOST DAYS FOR THE
COMING WEEK. OUR EXPECTATIONS IS FOR TODAY AND MONDAY TO AT LEAST
HAVE A 2 OR 3 PERIODS OF SHOWERS AND ISOLATED THUNDERSTORMS WITH
THE CAMS FAVORING LATE THIS AFTERNOON/EARLY EVENING, MONDAY
MORNING AND AGAIN LATER MONDAY. WE SHOULD HAVE PLENTY OF
INSOLATION TODAY RESULTING IN MODESTLY HIGH CAPE OF 1000-1500 J/KG
WITH LITTLE CIN LATER IN THE AFTERNOON INTO THE EVENING. ALTHOUGH
CAMS REALLY CAN'T AGREE ON CONVECTION FOR TODAY, IT IS LOGICAL
FOR STORMS (SOME POTENTIALLY STRONG) TO DEVELOP WITH A FOCUS OVER
HIGHER TERRAIN AREAS. CHANCES INTO THE SOUTH-CENTRAL ARIZONA LOWER
DESERTS ARE EXPECTED TO BE MORE LIMITED, BUT POPS HAVE BEEN
ADJUSTED UPWARD TO AT LEAST INCLUDE 10-15% CHANCES FOR EASTERN AND
NORTHERN PORTIONS OF THE PHOENIX METRO.
AFTER A BRIEF REPRIEVE IN RAIN CHANCES LATER THIS EVENING/EARLY
TONIGHT, A COUPLE HREF MEMBERS ARE POINTING AT A ROUND OF ELEVATED
SHOWERS AND EMBEDDED THUNDERSTORMS AT SOME POINT BETWEEN 3 AM-10
AM MONDAY. THE MORE LIKELY TIME FRAME FOR THIS TYPE OF CONVECTION
SHOULD BE A COUPLE HOURS BEFORE SUNRISE BEFORE GRADUALLY
DIMINISHING SHORTLY AFTER SUNRISE. GIVEN THE EXPECTED ELEVATED
NATURE OF THESE POTENTIAL SHOWERS AND STORMS, WE SHOULD ONLY
EXPECT LOCALIZED HEAVY RAINFALL AS THE ONLY THREAT. FOR THE LATTER
HALF OF MONDAY, THE BEST POTENTIAL FOR SHOWERS AND STORMS SHOULD
BE OVER SOUTHEAST ARIZONA AND POTENTIALLY INTO THE HIGHER TERRAIN
EAST OF PHOENIX. GIVEN THE FORECAST CAPE VALUES OF UP TO AROUND
1500 J/KG AND VERY RESPECTABLE LOW LEVEL MIXING RATIOS OF 13-14
G/KG, THIS SHOULD PRESENT A HEAVY RAINFALL AND LOCALIZED FLOOD
THREAT INTO SOUTHERN GILA COUNTY LATER MONDAY.
LONG TERM /TUESDAY THROUGH SATURDAY/
THE WEATHER PATTERN THROUGH AT LEAST THE MIDDLE OF THE WEEK WILL
CONTINUE TO SUPPORT GOOD MOISTURE LEVELS OVER AT LEAST THE
EASTERN HALF OF ARIZONA AND LIKELY IMPROVED UPPER LEVEL ASCENT FOR
TUESDAY-THURSDAY. TUESDAY MAY INVOLVE A BRIEF PERIOD OF DRIER AIR
MOVING INTO SOUTH-CENTRAL ARIZONA FROM THE SOUTHWEST AND THIS
SHOWS UP IN THE FAIRLY LIMITED POPS TUESDAY AFTERNOON/EVENING.
HOWEVER, NBM GUIDANCE SHOWS A RESURGENCE OF MOISTURE AND RAIN
CHANCES DURING THE OVERNIGHT HOURS TUESDAY NIGHT/WEDNESDAY
MORNING. CHANCES WEDNESDAY INTO THURSDAY ARE ALSO LOOKING BETTER
WITH A POTENTIAL DISTURBANCE TRACKING NORTHWARD INTO
CENTRAL/EASTERN ARIZONA AT SOME POINT. NEEDLESS TO SAY, THE MODEL
DIFFERENCES CALL INTO QUESTION THE BEST TIMING FOR RAIN CHANCES
AND THE EXACT AREAS, BUT AS LONG AS THE UPPER LEVEL SUPPORT AND
GOOD MOISTURE REMAIN PRESENT CHANCES WILL REMAIN ELEVATED.
WPC HAS ADDED A SLIGHT RISK ON THE DAYS 2-4 (MONDAY- WEDNESDAY)
EXCESSIVE RAINFALL OUTLOOKS OVER THE EASTERN ARIZONA HIGH
TERRAIN. IT WOULD NOT BE SURPRISING FOR SUBSEQUENT ISSUANCES OF
THE EROS TO EXTEND THE RISK THROUGH THURSDAY OR EVEN FRIDAY
DEPENDING ON THE FORECAST AVAILABLE MOISTURE. ALTHOUGH THE RISK
FOR HEAVY RAINFALL AND FLOODING WILL BE PRESENT THROUGH AT LEAST
THE MIDDLE OF THE WEEK, THE RISK FOR STRONG DOWNDRAFT/OUTFLOW
WINDS IS LIKELY TO DECREASE WITH GUIDANCE SHOWING DECREASING
FORECAST DCAPES. MODELS ARE STILL TRENDING TOWARD DRIER AIR
FINALLY MOVING EASTWARD THROUGH MOST OF ARIZONA BY FRIDAY OR
SATURDAY. THIS SHOULD MOSTLY SHUT DOWN RAIN CHANCES OVER THE LOWER
DESERTS AND DECREASE CHANCES OVER HIGHER TERRAIN AREAS.
TEMPERATURES THROUGHOUT THE ENTIRE WEEK ARE EXPECTED TO REMAIN
FAIRLY CLOSE TO SEASONAL NORMALS WITH THE LOWEST FORECAST HIGHS
OCCURRING ON TUESDAY AND WEDNESDAY. AS LONG AS MODELS ARE CORRECT
WITH THE DRYING TREND LATE IN THE WEEK INTO NEXT WEEKEND,
TEMPERATURES ARE FAVORED TO DRIFT BACK TO ABOVE NORMAL WITH HIGHS
MORE IN A 103-108 DEGREE RANGE BY FRIDAY OR SATURDAY.
AVIATION
UPDATED AT 0920Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
PRIMARY FORECAST UNCERTAINTY AND POTENTIAL IMPACT WILL BE THE
POSSIBILITY FOR VCSH/VCTS THIS AFTERNOON AND EVENING AND AGAIN
MONDAY MORNING. THIS AFTERNOON STORMS ARE FAVORED OUTSIDE JUST
OUTSIDE THE METRO, BUT THERE IS STILL A LOW CHANCE (5-10%) ACTIVITY
SPREADS INTO THE METRO BETWEEN 23-03Z. AN AREA OF SHOWERS AND STORMS
MAY ALSO DEVELOP IN THE METRO MONDAY MORNING AS EARLY AS 10Z, BUT
THIS LOOKS TO BE A CONDITIONAL SCENARIO AND CONFIDENCE IS LOW. WINDS
WILL MOSTLY FOLLOW TYPICAL DIURNAL TENDENCIES WITH SPEEDS BELOW 10
KTS AND WITH PERIODS OF LIGHT AND VARIABLE CONDITIONS. ANY SHOWERS
OR STORMS WILL BE CAPABLE OF GENERATING LOCALLY STRONG AND ERRATIC
WINDS. FEW TO SCT CLOUDS WILL BE COMMON THROUGH THE TAF PERIOD WITH
LOWEST BASES AROUND 8K FT AGL.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO AVIATION WEATHER CONCERNS EXPECTED UNDER MOSTLY CLEAR SKIES. AT
KIPL, WINDS WILL MOSTLY FAVOR THE SOUTHEAST, WITH A PERIOD OF
SOUTHWESTERLY THIS EVENING/TONIGHT. WIND SPEEDS AT KIPL WILL MOSTLY
STAY BELOW 10 KT WITH PERIODS OF LIGHT VARIABILITY. AT KBLH, WINDS
WILL CONTINUE TO FAVOR A SOUTHERLY COMPONENT WITH SPEEDS GENERALLY
BETWEEN 8-14 KT WITH SOME AFTERNOON GUSTS UP AROUND 20 KT.
FIRE WEATHER
CHANCES FOR SCATTERED SHOWERS AND ISOLATED STORMS WILL CONTINUE
TODAY BEFORE INCREASING AND BECOMING MORE WIDESPREAD INTO THE
SOUTH-CENTRAL ARIZONA LOWER DESERTS BEGINNING MONDAY. MOISTURE
LEVELS WILL REMAIN HIGH ENOUGH TO SUPPORT LOCALIZED HEAVY
RAINFALL WITH ANY STORMS. MINIMUM HUMIDITY LEVELS OVER THE NEXT
SEVERAL DAYS WILL ONLY FALL INTO A 15-25% RANGE IN WESTERN
DISTRICTS AND 25-40% IN EASTERN DISTRICTS. THIS WILL FOLLOW FAIR
TO GOOD OVERNIGHT RECOVERY OF 40-70%. OUTSIDE OF THUNDERSTORMS,
WINDS WILL GENERALLY REMAIN LIGHT WITH A SOUTHWEST HEADING THROUGH
NEARLY CALM CONDITIONS WILL BE COMMON IN THE MORNING HOURS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...KUHLMAN
LONG TERM...KUHLMAN
AVIATION...BENEDICT
FIRE WEATHER...KUHLMAN
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