217
FXUS65 KPSR 100837
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
137 AM MST SAT OCT 10 2026
KEY MESSAGES
- AN UNSETTLED WEATHER PATTERN WILL PREVAIL THROUGHOUT THE WEEKEND AS
THE REMNANTS OF TROPICAL CYCLONE RACHEL MOVE INTO THE SOUTHWEST
UNITED STATES, RESULTING IN HEIGHTENED CHANCES FOR SHOWERS AND
THUNDERSTORMS, WIDESPREAD GUSTY WINDS ON SUNDAY, AND MUCH COOLER
TEMPERATURES.
- RAIN CHANCES WILL CONTINUE FOR PORTIONS OF THE REGION, ESPECIALLY
ACROSS SOUTH-CENTRAL AZ, EARLY NEXT WEEK ALONG WITH WELL-BELOW
NORMAL TEMPERATURES.
- A DRIER AND QUIETER WEATHER PATTERN IS EXPECTED BY THE MIDDLE
AND LATTER PORTION OF NEXT WEEK ALONG WITH GRADUALLY WARMING
TEMPERATURES.
SHORT TERM /TODAY THROUGH SUNDAY/
AFTER A FAIRLY BENIGN WEATHER PATTERN ACROSS THE SOUTHWESTERN
UNITED STATES DURING THE LAST WEEK, BIG CHANGES ARE COMING FOR
THIS UPCOMING WEEKEND. CURRENT WATER VAPOR SATELLITE IMAGERY AS
WELL AS OBJECTIVE ANALYSIS SHOW A LARGE NORTHERN STREAM TROUGH
DIVING INTO THE PACIFIC NORTHWEST WHILE TROPICAL STORM RACHEL,
BEING STEERED NORTHEASTWARD BY ANOTHER CUTOFF LOW IS LOCATED
SEVERAL HUNDRED MILES TO THE SOUTH- SOUTHWEST OF SAN DIEGO. RACHEL
WILL CONTINUE TO MIGRATE NORTH- NORTHEASTWARD THROUGHOUT THE DAY,
MAKING LANDFALL ALONG THE FAR NORTHERN BAJA PENINSULA BY LATE
TONIGHT BEFORE ACCELERATING NORTH-NORTHEASTWARD THROUGH SAN DIEGO
AND WESTERN RIVERSIDE COUNTIES AND TOWARDS THE MOHAVE DESERT
DURING THE DAY SUNDAY.
SOUTH SOUTHWESTERLY FLOW WILL TRANSPORT ABUNDANT MOISTURE INTO
THE REGION THROUGHOUT THE DAY TODAY, WITH THE ENSEMBLES SHOWING
MEAN PWATS EXCEEDING OVER 200-250% OF NORMAL BY EARLY THIS
EVENING. THE INCREASING MOISTURE COMBINED WITH THE INCREASING JET
DYNAMICS FROM THE WEST COAST TROUGH WILL SUPPORT SCATTERED SHOWERS
AND STORMS TO BREAK OUT. LATEST HI-RES GUIDANCE SHOWS ACTIVITY,
MOSTLY IN THE FORM OF ELEVATED SHOWERS, DEVELOPING OVER SOUTHWEST
AZ STARTING LATE MORNING WITH SCATTERED SHOWERS AND STORMS
DEVELOPING ACROSS PORTIONS OF SOUTH-CENTRAL AZ THROUGH SOUTHEAST
CA DURING THE AFTERNOON/EARLY EVENING HOURS. SOME GUSTY WINDS AND
BRIEF HEAVY RAINFALL WILL BE THE MAIN THREATS WITH ANY STORMS THAT
MATERIALIZE AS INSTABILITY WILL BE QUITE MARGINAL WITH MUCAPE
VALUES AT LESS THAN 500 J/KG. THE CHANCES FOR MORE ROBUST
CONVECTION WILL LIKELY COME LATE TONIGHT INTO SUNDAY MORNING AS
BETTER LOW-LEVEL MOISTURE WITH THE ARRIVAL OF RACHEL WILL SUPPORT
A WINDOW OF HIGHER INSTABILITY UPWARDS OF 500-1000 J/KG OF MUCAPE.
THE HIGHER INSTABILITY COMBINED WITH VERTICAL WIND SHEAR IN
EXCESS OF 40 KTS WILL SUPPORT A SEVERE THREAT, WITH SPC
HIGHLIGHTING MUCH OF THE AREA UNDER A MARGINAL RISK. DAMAGING WIND
GUSTS WILL BE THE MAIN THREAT, HOWEVER, WITH LOW-LEVEL SHEAR
INCREASING ABOVE 20 KTS ALONG WITH 0-3 KM STORM RELATIVE HELICITY
OVER 100-200 M2/S2, THERE WILL BE A NON-ZERO THREAT FOR A BRIEF
TORNADO OR TWO.
AS THE REMNANTS OF RACHEL APPROACH SOUTHERN CA COMBINED WITH HEIGHT
FALLS FROM THE LARGE SCALE TROUGH TO THE WEST, LOW-LEVEL WINDS WILL
BE INCREASING WITH A BELT OF 850 MB UPWARDS OF 50 KTS. THIS WILL
SUPPORT NON-THUNDERSTORM WIND GUSTS EXCEEDING 40 MPH STARTING AFTER
MIDNIGHT ACROSS SOUTHEAST CA INTO SOUTHWEST AZ BEFORE THE STRONGER
WINDS SPREAD FURTHER EAST INTO SOUTH-CENTRAL AZ BY THE EARLY TO MID-
MORNING HOURS SUNDAY. WIND GUSTS THIS HIGH COULD CERTAINTY RESULT IN
AREAS OF BLOWING DUST IN THE DUST PRONE AREAS. AS THE REMNANTS OF
RACHEL MOVE NORTHWARD INTO SOUTHERN NEVADA BY LATE SUNDAY
AFTERNOON/EARLY EVENING, WINDS WILL WEAKEN AS THE GRADIENT WEAKENS.
IN TERMS OF RAINFALL AMOUNTS, GIVEN THAT MUCH OF THE ACTIVITY WILL
BE MOSTLY SCATTERED IN NATURE, AMOUNTS ACROSS MUCH OF THE AREA WILL
BE UNDER 0.75" WITH THE POTENTIAL THAT SOME AREAS SEE NEXT TO
NOTHING. HOWEVER, THERE CAN BE SOME LOCALLY HIGHER AMOUNTS IN EXCESS
OF 1" IN AREAS THAT SEE A TRAINING OF CONVECTION. THE MORE FAVORABLE
AREA FOR MORE WIDESPREAD ACTIVITY WILL BE MAINLY ACROSS JOSHUA TREE
NATIONAL PARK, CLOSE TO WHERE RACHEL WILL TRACK, AND THUS THE
POTENTIAL WILL EXIST FOR MORE WIDESPREAD AMOUNTS IN EXCESS OF 1"
WITH A FLOOD WATCH IN EFFECT FROM THIS EVENING THROUGH SUNDAY
AFTERNOON.
AFTER THE COUPLE OF DAYS OF WIDESPREAD HIGHS IN THE TRIPLE DIGITS,
TEMPERATURES THIS WEEKEND WILL STEADILY COOL. LOWER DESERT HIGHS
THIS AFTERNOON WILL BE ABOUT 10 DEGREES COOLER COMPARED TO FRIDAY
WITH READINGS IN THE LOW TO MID 90S. THE MORE ABUNDANT CLOUD COVER
AS WELL AS RAINFALL ACTIVITY WILL CAUSE TEMPERATURES TO COOL ANOTHER
7-10 DEGREES ON SUNDAY AS AFTERNOON HIGHS ONLY REACH THE LOW TO
MIDDLE 80S.
LONG TERM /MONDAY THROUGH FRIDAY/
UNSETTLED WEATHER WILL CONTINUE THROUGH EARLY NEXT WEEK AS THE LARGE-
SCALE TROUGH THAT WILL SETTLE ACROSS THE WEST COAST OVER THE WEEKEND
WILL GRADUALLY MIGRATE EASTWARD. THE ASSOCIATED LARGE-SCALE FORCING
FOR ASCENT COMBINED WITH AMPLE LOW-LEVEL MOISTURE WILL SUPPORT
SCATTERED SHOWERS AND EMBEDDED THUNDERSTORMS DURING THE DAY, MAINLY
ACROSS THE FOOTHILLS AND HIGHER TERRAIN AREAS NORTH AND EAST OF
PHOENIX IN UPSLOPE FLOW. THEREAFTER, AS THE MAIN COLD FRONT
ASSOCIATED WITH THE TROUGH MOVES THROUGH LATE MONDAY NIGHT INTO
TUESDAY MORNING, THERE WILL LIKELY BE A BAND OF SHOWERS WITH
EMBEDDED THUNDERSTORMS THAT MOVES THROUGH, PARTICULARLY ACROSS SOUTH-
CENTRAL AZ, BEFORE RAIN CHANCES END BY TUESDAY AFTERNOON/EVENING AS
DRIER AIR FILTERS IN. AT THIS POINT ANY OF THE RAIN THAT FALLS EARLY
NEXT WEEK WILL GENERALLY BE OF THE NUISANCE TYPE. QUIETER WEATHER
WITH NEAR ZERO RAIN CHANCES CAN BE EXPECTED STARTING WEDNESDAY
AND WILL PERSIST THROUGH THE END OF THE WEEK.
WITH THE PRESENCE OF THE TROUGH AS WELL AS MORE ABUNDANT CLOUD
COVER, WELL-BELOW NORMAL TEMPERATURES ARE EXPECTED DURING THE FIRST
HALF OF THE WEEK WITH MANY OF THE LOWER DESERT LOCATIONS LIKELY
STAYING IN THE 70S FOR AFTERNOON HIGHS. EARLY MORNING LOWS WILL ALSO
BE BELOW NORMAL WITH THE COOLEST MORNING EXPECTED ON WEDNESDAY WHEN
MANY AREAS ARE EXPECTED TO DROP INTO THE 50S WITH EVEN SOME 40S
ACROSS THE HIGHER TERRAIN AREAS. TEMPERATURES WILL THEN GRADUALLY
REBOUND INTO THE 80S BY THE LATTER PORTION OF THE WEEK.
AVIATION
UPDATED AT 0540Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
THE PRIMARY WEATHER ISSUES WILL BE SHRA AND POTENTIALLY EMBEDDED
TSRA ENTERING THE PHOENIX METRO SATURDAY AFTERNOON AND EVENING, AND
SUBSEQUENT THE EFFECT ON WINDS AS MIDLEVEL CIGS DEVELOP AND LOWER.
CONFIDENCE IS GOOD THAT E/SE WINDS WILL PREVAIL THROUGH SATURDAY
MORNING AS 10-15K FT AGL CIGS FILL IN ACROSS THE AREA. SCATTERED
SHRA SHOULD ENTER THE WESTERN PORTIONS OF THE METRO EARLY SATURDAY
AFTERNOON, AND MAY ALLOW WINDS TO SHIFT TO A W/SW DIRECTION.
COVERAGE OF SHRA APPEARS LOW ENOUGH TO PRECLUDE A PREDOMINANT
MENTION, AND WILL ADVERTISE A PROLONGED PERIOD OF VCSH. A FEW
EMBEDDED TSRA WILL ALSO BE POSSIBLE HEADING INTO THE EVENING, BUT
ODDS ONLY JUSTIFY A PROB30 MENTION AT THIS TIME WITH POTENTIALLY
ERRATIC, GUSTY WINDS. CONFIDENCE IS BETTER THAT AN EAST COMPONENT
WILL SETTLE BACK INTO THE AREA SATURDAY NIGHT, AND HAVE KEPT A VCSH
MENTION THOUGH ITS MORE UNCERTAIN HOW EXPANSIVE SHRA WILL BE.
SUNDAY OUTLOOK: HIGH IMPACT WEATHER STILL APPEARS TO BE ARRIVING AT
ALL TERMINALS SUNDAY MID/LATE MORNING THROUGH THE AFTERNOON.
SHRA/TSRA SHOULD SURGE INTO THE AREA WITH GUSTY SOUTH WINDS AND
MVFR/IFR CIGS. THE LOWER CIGS AND TSRA THREAT SHOULD BE RATHER SHORT
LIVED OVER A 3-4 HOUR WINDOW LATE MORNING THROUGH EARLY AFTERNOON
BEFORE LIFTING OUT OF THE AERODROME SPACE. HOWEVER, VERY STRONG S/SW
WINDS WILL FILL IN BEHIND THE SHRA WITH GUSTS 30KT OR HIGHER
THROUGHOUT THE AFTERNOON.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
PERIODS OF SHRA WITH THE POTENTIAL FOR ISOLATED TSRA ALONG WITH
ERRATIC WIND DIRECTIONS WILL BE THE MAIN WEATHER ISSUES AS THICK
MIDLEVEL CIGS DEVELOP OVER THE AREA. WINDS SHOULD BECOME MORE
VARIABLE IN DIRECTION OVERNIGHT, THEN OBTAINING AN E/SE COMPONENT
SATURDAY. SCATTERED SHOWERS WOULD MOST LIKELY IMPACT KBLH BY EARLY
AFTERNOON AS 10K FT CIGS COVER THE AREA. AT THIS POINT, A VCSH
ADEQUATELY DESCRIBES THE COVERAGE, THOUGH ENOUGH ODDS FOR TSRA EXIST
AT KBLH TO INCLUDE A PROB30. UNCERTAINTY IN WINDS AND WEATHER GROW
SIGNIFICANTLY SATURDAY NIGHT AND SUNDAY AS A PERIOD OF HIGH IMPACT
WEATHER MOVES INTO THE REGION.
FIRE WEATHER
A MUCH MORE UNSETTLED WEATHER PATTERN WILL DEVELOP OVER THE WEEKEND
AS INCREASING MOISTURE ASSOCIATED WITH THE REMNANTS OF TROPICAL
STORM RACHEL BRINGS INCREASING RAIN CHANCES. THE CHANCES FOR
SHOWERS AND STORMS INCREASE STARTING THIS AFTERNOON/EVENING AND
CONTINUES INTO SUNDAY WITH A GREATER THAN 50-70% CHANCE OF WETTING
RAINFALL AREA WIDE. WINDS WILL ALSO INCREASE SIGNIFICANTLY,
ESPECIALLY LATE TONIGHT THROUGH SUNDAY WITH WIDESPREAD GUSTS
EXCEEDING 30-40 MPH. WITH THE INCREASING MOISTURE AND COOLER
TEMPERATURES, MINRH VALUES WILL INCREASE FROM 25-40% TODAY TO
45-70% ON SUNDAY ALONG WITH GOOD TO EXCELLENT OVERNIGHT
RECOVERIES. ANOTHER WEATHER SYSTEM WILL BRING ADDITIONAL CHANCES
FOR WETTING RAINFALL EARLY NEXT WEEK, MAINLY FOR THE EASTERN
DISTRICTS, BEFORE QUIETER WEATHER SETTLES IN BY THE MIDDLE OF THE
WEEK. TEMPERATURES WILL STEADILY COOL THIS WEEKEND, WITH WELL-
BELOW NORMAL TEMPERATURES EXPECTED FOR THE FIRST HALF OF THE NEXT
WEEK.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...WIND ADVISORY FROM 2 AM TO 5 PM MST SUNDAY FOR AZZ530>533-535-
536.
WIND ADVISORY FROM 8 AM TO 5 PM MST SUNDAY FOR AZZ534-537>563.
CA...WIND ADVISORY FROM 2 AM TO 5 PM PDT SUNDAY FOR CAZ560>570.
FLOOD WATCH FROM THIS AFTERNOON THROUGH SUNDAY AFTERNOON FOR
CAZ560-561-568.
SHORT TERM...LOJERO
LONG TERM...LOJERO
AVIATION...18
FIRE WEATHER...LOJERO
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