995
FXUS65 KPSR 131110
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
410 AM MST SAT JUN 13 2026
UPDATE
12Z AVIATION DISCUSSION
KEY MESSAGES
- TEMPERATURES AROUND 3 TO 8 DEGREES ABOVE DAILY NORMALS WILL
RESULT IN WIDESPREAD MODERATE HEAT RISK, WITH ISOLATED POCKETS
OF MAJOR HEAT RISK AT TIMES, THROUGH THE MIDDLE OF NEXT WEEK.
- CHANCES FOR SHOWERS AND THUNDERSTORMS WILL MOSTLY BE FOCUSED
OVER THE NORTHERN ARIZONA HIGH TERRAIN AND PORTIONS OF SOUTHEAST
ARIZONA THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK.
- BRIEF GUSTY WINDS FROM DISTANT OUTFLOWS AND LOW PROBABILITIES
FOR A THUNDERSTORM OR TWO OVER THE NORTHERN AND EASTERN
FOOTHILLS OF MARICOPA COUNTY CANNOT BE RULED OUT TODAY AND
SUNDAY IN THE LATE AFTERNOON TO EVENING TIME FRAME.
SHORT TERM /TODAY THROUGH SUNDAY/
IN THE NORTHERN STREAM, TWO FEATURES WILL BE PRESENT AND NEARLY
STATIONARY OVER THE NEXT WEEK: UPPER LEVEL RIDGING OFF THE WEST
COAST AND LONGWAVE TROUGHING DOWNSTREAM OVER THE NORTH-CENTRAL
CONUS. WHILE THESE FEATURES WILL HAVE SOME INFLUENCE ON THE LOCAL
CONDITIONS, THE MORE RELEVANT FEATURE WILL BE A SUBTROPICAL HIGH
AND ASSOCIATED ANTICYCLONIC FLOW TO THE SOUTHEAST OF THE REGION.
ABUNDANT MOISTURE HAS OVERSPREAD THE REGION UNDER A PERIOD OF
SOUTHERLY FLOW, WITH SURFACE DEWPOINT TEMPERATURES RANGING FROM
THE UPPER 40S TO LOWER 60S AND CURRENT RAP ANALYZED PWATS UPWARDS
OF 1.0- 1.3" OVER THE FORECAST AREA, REPRESENTING VALUES AROUND
THE 99TH PERCENTILE OF CLIMATOLOGY FOR MID JUNE. HOWEVER, MIDLEVEL
WATER VAPOR IMAGERY AND 500 MB STREAMLINE ANALYSIS SEEM TO
INDICATE THE FLOW ALOFT ALREADY SHIFTING OUT OF THE SOUTHWEST AS
AN UPPER LOW OFF THE BAJA SHIFTS FURTHER OFFSHORE AND THE
SUBTROPICAL HIGH ASSERTS ITSELF FURTHER WEST. WITH THIS SHIFT, THE
AREA OF BETTER SYNOPTIC ASCENT HAS ALSO SHIFTED AWAY FROM THE
FORECAST AREA. LOW AND MID LEVEL MOISTURE WILL REMAIN IN PLACE
ACROSS MUCH OF THE STATE THROUGH THE WEEKEND AND EVEN LINGER INTO
NEXT WEEK, BUT THE LIFT NECESSARY FOR SHOWERS AND STORMS WILL
MOSTLY HAVE TO COME FROM DIURNAL UPSLOPE CONVERGENCE/OROGRAPHIC
INFLUENCES GOING FORWARD, RELEGATING THE BEST CHANCES FOR SHOWERS
AND STORMS TO THE NORTHERN AZ HIGH TERRAIN AND PORTIONS OF FAR
SOUTHEAST AZ NEAR THE INTERNATIONAL BORDER.
LATEST HREF MEMBERSHIP SUPPORTS THE EVOLUTION DESCRIBED, WITH
CONVECTIVE SHOWERS AND THUNDERSTORMS DEVELOPING OVER THE NORTHERN
AZ HIGH TERRAIN BY LATE THIS MORNING AND FAR SOUTHEAST AZ THIS
AFTERNOON. MEAN MUCAPES UPWARDS OF 250 J/KG TO AS MUCH AS 750 J/KG
AND INVERTED-V SOUNDINGS WILL MEAN THAT LOCALLY STRONG, GUSTY
WINDS ARE A CONCERN WITH ANY STRONGER STORMS THAT DEVELOP,
HOWEVER, THEY WILL BE ALMOST ENTIRELY OUTSIDE THE CWA. IT IS
CONCEIVABLE (AND SOME CAMS DO SUPPORT THIS) THAT AN ORGANIZED
OUTFLOW COULD FORM AND ACCELERATE DOWNHILL INTO SOUTH-CENTRAL AZ
BY THE LATE AFTERNOON/EVENING, PROVIDING ENOUGH LIFT TO TRIGGER A
THUNDERSTORM OR TWO OVER THE NORTHERN/NORTHEASTERN FOOTHILLS OF
MARICOPA COUNTY. ON SUNDAY, A SIMILAR SCENARIO MAY PLAY OUT, BUT
WITH A FEW NOTABLE DIFFERENCES: HIGHER INSTABILITY (CAPE PEAKING
BETWEEN 500-1000 J/KG), BUT DRIER MIDLEVELS THANKS TO THE
SUSTAINED WEST SOUTHWEST FLOW ALOFT THROUGH THE WEEKEND. THIS
DRIER AIR ALOFT WILL ENTRAIN WITHIN UPDRAFTS, EFFECTIVELY REDUCING
THE INTENSITY OF CONVECTION FROM WHAT MEASURES OF INSTABILITY
MIGHT SUGGEST. THERE IS SOME INHERENT UNCERTAINTY HERE TO KEEP
AWARE OF THROUGH THIS WEEKEND; ENOUGH MOISTURE AND INSTABILITY
WILL BE PRESENT FOR SHOWERS AND STORMS, BUT SYNOPTIC ASCENT
MECHANISMS ARE LARGELY ABSENT. SUBTLE LIFTING MECHANISMS (E.G., A
DISTANT OUTFLOW FROM EARLIER NORTHERN AZ CONVECTION, OR GRAVITY
WAVES RELEASING ELEVATED INSTABILITY IN THE OVERNIGHT/MORNING
PERIODS) AND ADDITIONAL MOISTURE INFLUXES (STRONG, DISTANT,
MOISTURE-LADEN OUTFLOWS FROM VIGOROUS CONVECTION IN SONORA) WILL
PLAY A KEY ROLE IN WHAT ACTIVITY WE ACTUALLY SEE. WE CANNOT RULE
OUT SHOWERS AND STORMS, THOUGH CURRENT POPS AND THUNDER
PROBABILITIES MAY BE TOO LOW TO APPEAR IN POINT AND CLICK
FORECASTS.
LOWER DESERTS HIGHS WILL REMAIN IN A 103F-110F RANGE, PERHAPS A
DEGREE OR TWO WARMER SUNDAY THAN TODAY, AS THE SUBTROPICAL HIGH
CONTINUES TO INCH CLOSER TO THE REGION. CURRENT H5 HEIGHTS ARE
SITTING BETWEEN 589-590 DAM AND EXPECTED TO CLIMB SLIGHTLY BY
SUNDAY HEADING INTO NEXT WEEK TO NEAR 590-591 DAM. OVERNIGHT LOW
TEMPERATURES WILL ALSO BE ABOVE NORMAL OVER THE WEEKEND, BY 5F-8F,
PUTTING OVERNIGHT LOWS IN THE UPPER 70S TO MID 80S ACROSS THE
LOWER DESERT AREAS. THIS HAS LEAD TO WIDESPREAD MODERATE TO
LOCALIZED MAJOR HEATRISK. WITH THE ABSENCE OF MUCH OVERNIGHT/
EARLY MORNING RELIEF FROM THE HEAT ENSURE TO STAY HYDRATED AND
FOLLOW HEAT SAFETY PRECAUTIONS.
LONG TERM /MONDAY THROUGH FRIDAY/
LOW LEVEL MOISTURE WILL NOT BE SCOURED OUT HEADING INTO NEXT
WEEK, ESPECIALLY FOR THE SOUTHEASTERN CORNER OF THE STATE, AND SO
A CONTINUATION OF DIURNALLY DRIVEN, HIGH TERRAIN SHOWERS/STORMS
LOOKS LIKELY. ACTIVITY WILL BE REDUCED AT TIMES DUE TO PERIODS OF
STRONGER SUBSIDENCE, ONE OF WHICH IS CAPTURED AS A STRONGER
MIDLEVEL INVERSION IN GFS BUFR SOUNDINGS DURING THE TUESDAY-
WEDNESDAY TIMEFRAME. THIS STRONGER ANTICYCLONIC SUBSIDENCE IS ALSO
EXPECTED TO SUPPORT TEMPERATURES A FEW DEGREES WARMER, DESPITE
FAIRLY STABLE H5 HEIGHTS, RESULTING IN A VERY MODEST EXPANSION OF
MAJOR HEATRISK ACROSS THE WESTERN DESERTS. THE PATTERN WILL CHANGE
MORE NOTICEABLY BY THE END OF THE WORK WEEK, AS ENSEMBLES ARE
POINTING TOWARDS A STRONGER SUBTROPICAL JET STREAK MOVING CLOSER
TO AND EVENTUALLY ONSHORE SOMEWHERE ALONG CALIFORNIA/NORTHERN BAJA
(NORTH/SOUTH DISCREPANCIES ARE APPARENT BETWEEN THE DIFFERENT
ENSEMBLE SUITES). THIS WILL INCREASE WINDS REGIONALLY AS THE
SUBTROPICAL JET IMPARTS DEEP SOUTHWESTERLY FLOW, DECREASE HEIGHTS
ALOFT, AND SUBSTANTIALLY SCOUR OUT THE LOW LEVEL MOISTURE ACROSS
THE REGION. AS A RESULT, ANTICIPATE ELEVATED FIRE WEATHER
CONCERNS, ESPECIALLY FOR SOUTHEAST CA AND SOUTHWEST AZ,
TEMPERATURES MODERATING CLOSER TO DAILY NORMALS, AND THE DIURNALLY
DRIVEN SHOWER/STORM CHANCES OVER AZ HIGH TERRAIN TO END.
AVIATION
UPDATED AT 1110Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
THE POTENTIAL FOR WEAK OUTFLOWS THIS EVENING WILL BE THE MAIN
AVIATION QUESTION DURING THE PERIOD. IT APPEARS NOW THAT THE USUAL
E'RLY SHIFT AT KPHX HAS BETTER POTENTIAL OF TAKING PLACE, BUT A
VRB GROUP REMAINS IN THE TAF TO INDICATE LINGERING UNCERTAINTY.
OUTSIDE OF THIS WINDOW, W'RLY FLOW WILL BE COMMON DURING THE
MAJORITY OF THE FORECAST. THE ONLY INTERRUPTION TO THIS PATTERN
MAY BE THE PRESENCE OF WEAK OUTFLOWS, MENTIONED ABOVE,
ORIGINATING FROM DISTANT CONVECTION. HOWEVER, GUIDANCE CONTINUES
TO BACK AWAY FROM THIS OUTCOME, SO NE'RLY SHIFTS AT KDVT AND KSDL
HAVE BEEN REPLACED WITH TYPICAL EVENING VRB GROUPS. THE POTENTIAL
FOR AN OUTFLOW IS NOT ZERO, BUT THEY WILL HIGHLY DEPENDENT ON
CONVECTIVE LOCATION, THEREFORE, AMENDMENTS MAY BE NEEDED AS WE
MOVE THROUGH THE DAY. KDVT AND KSDL WOULD BE THE MOST LIKELY TO
OBSERVE ANY OUTFLOW SWITCHES. FEW-SCT MID-LEVEL CLOUDS WILL BE
PRESENT BUT SHOULD GRADUALLY CLEAR THROUGH TODAY.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR WEATHER CONCERNS SHOULD EXIST THROUGH SATURDAY NIGHT
UNDER MOSTLY CLEAR SKIES. CONFIDENCE IS GOOD THAT A SOUTHERLY WIND
COMPONENT WITH OCCASIONAL GUSTINESS WILL BE MAINTAINED AT KBLH
WHILE DIRECTIONS OSCILLATE BETWEEN SSE AND SW AT KIPL. SOME
STRONGER 20-30KT SUNDOWNER GUSTS WILL BE POSSIBLE AT KIPL
SATURDAY EVENING, THOUGH CONFIDENCE IS ONLY LOW TO MODERATE.
FIRE WEATHER
TEMPERATURES 3-8 DEGREES ABOVE NORMAL WILL PREVAIL WITH LOWER DESERT
HIGHS NEAR 110F IN SOME OF THE HOTTER SPOTS THROUGH THE MIDDLE OF
NEXT WEEK. IMPROVED HUMIDITY LEVELS WILL PREVAIL THROUGH THE
WEEKEND, WITH AFTERNOON MINIMUMS GENERALLY BETWEEN 15-20% AND
OVERNIGHT RECOVERIES AS LOW AS 25% IN THE FAR WESTERN DISTRICTS
AND BETWEEN 35-50% FOR MOST OTHER AREAS. WITH THE INCREASING
MOISTURE WILL ALSO COME SLIGHT CHANCES FOR ISOLATED SHOWER AND
THUNDERSTORM ACTIVITY. CHANCES WILL BECOME ALMOST ENTIRELY
CONFINED TO THE HIGH TERRAIN OF THE EASTERN DISTRICTS BY THIS
AFTERNOON. RAINFALL POTENTIAL WILL BE LIMITED, SO LOCALLY GUSTY
OUTFLOW WINDS AND DRY LIGHTNING POTENTIALLY LEADING TO NATURAL
FIRE STARTS ARE THE MAIN CONCERNS. WINDS WILL GENERALLY REMAIN
TERRAIN-DRIVEN OUTSIDE THE INFLUENCE OF THUNDERSTORM OUTFLOWS,
WITH SPEEDS AT OR BELOW 15 MPH AND AFTERNOON/EARLY EVENING UPSLOPE
AND UPVALLEY GUSTS UP TO 25 MPH.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...WHITTOCK
LONG TERM...WHITTOCK
AVIATION...18/RW
FIRE WEATHER...WHITTOCK/RYAN
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