580
FXUS65 KPSR 041931
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1231 PM MST FRI SEP 4 2026
KEY MESSAGES
- RESIDUAL MOISTURE MAY SPARK A FEW SHOWERS AND STORMS THIS
AFTERNOON, MAINLY SOUTH AND EAST OF PHOENIX.
- THE MOISTURE AXIS AND CORRESPONDING RAIN CHANCES WILL SHIFT WEST INTO
SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA DURING THE WEEKEND.
- TEMPERATURES WILL REMAIN NEAR TO SLIGHTLY BELOW NORMAL THROUGH THIS
WEEKEND BEFORE WARMING TO SLIGHTLY ABOVE NORMAL BY EARLY NEXT
WEEK.
SHORT TERM /TODAY THROUGH SUNDAY/
THE OVERALL SYNOPTIC PATTERN CONTINUES TO BE DEFINED BY AN ELONGATED
RIDGE OF HIGH PRESSURE EXTENDING FROM THE SOUTHERN PLAINS INTO
THE SOUTHEASTERN U.S. WHILE A BROAD TROUGH ENCOMPASSES MUCH OF THE
PACIFIC NORTHWEST AND WEST COAST. DUE TO THIS PATTERN
CONFIGURATION, THE DESERT SOUTHWEST REMAINS UNDER DRY SOUTHWESTERLY
FLOW ALOFT. RESIDUAL LOW-LEVEL MOISTURE FROM HURRICANE MARIE,
CENTERED WELL TO THE WEST OF THE SOUTHERN TIP OF THE BAJA
PENINSULA, REMAINS ACROSS MUCH SOUTH-CENTRAL AND SOUTHEAST AZ
WITH DEWPOINTS IN THE 60S WHILE MUCH DRIER AIR WITH DEWPOINTS IN
THE 30S AND 40S ENCOMPASSES MUCH OF SOUTHEAST CA AND SOUTHWEST AZ.
THE RESIDUAL MOISTURE WILL STILL COMBINE WITH STRONG DAYTIME
HEATING TO CAUSE CUMULUS BUILDUPS HEADING INTO THIS AFTERNOON
ACROSS SOUTH-CENTRAL AZ WITH THE POTENTIAL FOR A FEW SHOWERS AND
STORMS TO DEVELOP, MAINLY ACROSS THE TERRAIN ESCARPMENTS. HOWEVER,
AS THE AFTERNOON PROGRESSES, DRIER AIR WILL BE FILTERING IN FROM
THE WEST, WHICH WILL ERODE THE LOW-LEVEL MOISTURE SOMEWHAT AND
THUS REDUCE INSTABILITY SIGNIFICANTLY WITH THE LATEST FORECAST
SOUNDINGS FROM PHOENIX SHOWING CAPE VALUES DROPPING FROM OVER 1000
J/KG EARLIER TODAY TO LESS THAN 100-200 J/KG BY THIS AFTERNOON.
THEREFORE, ANY CONVECTIVE CELLS THAT ATTEMPT TO DEVELOP THIS AFTERNOON
WILL BE VERY SHORT-LIVED.
AS HURRICANE MARIE CONTINUES TO MOVE NORTHWESTWARD WELL OFFSHORE
FROM THE BAJA PENINSULA OVER THE WEEKEND, SOME ADDITIONAL MOISTURE
WILL BE TRANSPORTED NORTHWARD BUT THIS TIME TOWARDS SOUTHERN CA AND
SOUTHWEST AZ AS PWATS RISE TO AROUND 1.6-1.8". THEREFORE, RAIN
CHANCES HEADING INTO THIS WEEKEND WILL BE MAINLY CONFINED ACROSS
THESE AREAS WITH POPS ONLY TOPPING OUT BETWEEN 10-20%. AN ABUNDANCE
OF MID TO UPPER-LEVEL MOISTURE WILL RESULT IN EXTENSIVE MID-HIGH
CLOUDS ACROSS MUCH OF THE AREA SO AS A RESULT MID-LEVEL LAPSE RATES
AND THUS INSTABILITY WILL BE VERY POOR WITH FORECAST SOUNDINGS
SHOWING LITTLE TO NO CAPE. AS A RESULT, ANY RAINFALL ACTIVITY THAT
MATERIALIZES WILL BE ON THE LIGHT SIDE WITH LITTLE TO NO IMPACTS. IN
FACT, MUCH OF THE ACTIVITY THAT FALLS ON SATURDAY ACROSS SOUTHEAST
CA AND SOUTHWEST AZ MAY ACTUALLY BE VIRGA GIVEN THAT THE LOW-
LEVELS WILL REMAIN VERY DRY AS DEWPOINTS WILL STILL BE IN THE 30S
AND 40S. BETTER LOW-LEVEL MOISTURE IS EXPECTED HEADING INTO
SUNDAY, HOWEVER, THE BETTER FORCING FOR ASCENT FROM AN UPPER-
LEVEL JET STREAK IS LIKELY TO SHIFT NORTHWARD TOWARDS THE MOHAVE
DESERT REGION, WHERE THE BEST RAIN CHANCES WILL BE LOCATED. FAIRLY
QUIET WEATHER IS EXPECTED THIS WEEKEND ACROSS MUCH OF SOUTH-
CENTRAL AZ AS THE LACK OF INSTABILITY AND FORCING FOR ASCENT WILL
HINDER STORM ACTIVITY.
THE CONTINUED PRESENCE OF TROUGHING TO OUR WEST WILL CONTINUE TO
MAINTAIN TEMPERATURES NEAR TO SLIGHTLY BELOW NORMAL LEVELS THROUGH
THE WEEKEND WITH HIGHS GENERALLY IN THE UPPER 90S TO LOW 100S,
WITH SATURDAY EXPECTED TO BE THE COOLEST DAY. IN FACT, DUE TO THE
PRESENCE OF ABUNDANT MID TO HIGH CLOUDS ACROSS MUCH OF THE WESTERN
DESERTS ON SATURDAY, TEMPERATURES MAY STRUGGLE TO REACH THE
TRIPLE DIGITS. THE ASSOCIATED HEIGHT FALLS FROM THE TROUGHING TO
OUR WEST WILL ALSO RESULT IN ANOTHER ROUND OF AFTERNOON/EARLY
EVENING BREEZINESS TODAY ACROSS MUCH OF SOUTHEAST CA AND SOUTHWEST
AZ WITH PEAK GUSTS AROUND 20-30 MPH, POTENTIALLY REACHING UP TO
40 MPH IN THE TYPICAL WIND PRONE AREAS OF FAR SOUTHWEST IMPERIAL
COUNTY. SLIGHTLY WEAKER WINDS ARE ANTICIPATED DURING THE WEEKEND.
LONG TERM /MONDAY THROUGH THURSDAY/
DETERMINISTIC AND ENSEMBLE GUIDANCE CONTINUE TO DIFFER ON THE
MAGNITUDE AND POSITIONING OF THE SUBTROPICAL RIDGE EARLY NEXT WEEK
WHICH WILL DICTATE HOW HOT TEMPERATURES GET AND HOW SOON RAIN
CHANCES WILL RETURN TO OUR AREA. BOTH THE EPS AND GEFS SHOW THE
RIDGE STRENGTHENING OVER THE SOUTHERN PLAINS THROUGH THE MIDDLE OF
THE WEEK WHICH WILL ALLOW HGHTS ALOFT TO INCREASE ACROSS MUCH OF
THE DESERT SOUTHWEST. IN TURN, TEMPERATURES WILL ALSO INCREASE
FROM NEAR NORMAL MONDAY TO SLIGHTLY ABOVE NORMAL ON TUESDAY. THE
TEMPERATURE FORECAST BECOMES MUCH MORE UNCLEAR HEADING INTO THE
MIDDLE OF NEXT WEEK WITH LARGE SPREADS IN THE NBM INTERQUARTILE
RANGE. THIS IS LIKELY DUE TO DIFFERENCES IN THE MAGNITUDE OF THE
RIDGE WITH MANY EPS MEMBERS SHOWING A STRONGER RIDGE WITH 500 MB
HGHTS APPROACHING 596-598 DAM WHILE THE GEFS SHOWS SLIGHTLY LOWER
OVERALL HGHTS. FOR NOW NBM TEMPERATURES SHOW A COOLING TREND AFTER
TUESDAY WHICH IS LIKELY DUE TO AN INCREASE IN MOISTURE AS
SOUTHEASTERLY FLOW ALOFT RETURNS TO THE LOWER DESERTS.
PWATS ARE EXPECTED TO INCREASE BACK TO AROUND 1.5-1.8" BY THE
MIDDLE OF NEXT WEEK WHICH WILL BRING RAIN CHANCES BACK INTO THE
PICTURE BY THE WEDNESDAY-THURSDAY TIMEFRAME WHEN POPS INCREASE TO
AROUND 20-40% AREAWIDE. THE GFS IS EVEN SHOWING AN EASTERLY
WAVE/INVERTED TROUGH ARRIVING INTO SOUTHERN AZ ALONG WITH
ADDITIONAL TROPICAL PACIFIC MOISTURE ON WEDNESDAY WHICH COULD
BOOST RAIN CHANCES SIGNIFICANTLY, BUT WE WILL LIKELY HAVE TO WAIT
FOR MORE RUN TO RUN CONSISTENCY AS THESE FEATURES ARE ALWAYS
DIFFICULT TO RESOLVE AT LONGER TIME SCALES. EITHER WAY, MOST OF
THE GEFS AND EPS MEMBERS ARE SHOWING MEASURABLE PRECIPITATION
ACROSS PORTIONS OF THE AREA BY THE MIDDLE OF NEXT WEEK.
AVIATION
UPDATED AT 1826Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
WINDS WILL FOLLOW A SIMILAR PATTERN TO YESTERDAY, WITH A SSE-SSW
DIRECTION FOR MOST OF THE DAY AND A VEERING TREND TO W-SW THIS
EVENING. WIND SPEEDS WILL MOSTLY BE IN THE 5-10 KT RANGE WITH
OCCASIONAL GUSTS INTO THE TEENS. SCATTERED CUMULUS, BASED AROUND
10K FT AGL, WILL DEVELOP THROUGH THIS AFTERNOON WITH A VERY LOW
CHANCE (5-10%) FOR A BRIEF ISOLATED SHOWER OR STORM LATE THIS
AFTERNOON AND EVENING. LIGHT E'RLY WINDS WILL EVENTUALLY DEVELOP
AFTER MIDNIGHT TONIGHT AND THEN A S'RLY COMPONENT WILL DEVELOP
AGAIN BY MIDDAY SATURDAY, BUT A QUICKER MORE PRONOUNCED W'RLY
SHIFT IS ANTICIPATED SATURDAY AFTERNOON. SCT HIGH CLOUDS WILL
OVERSPREAD THE AREA SATURDAY.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
AFTERNOON THROUGH EARLY EVENING GUSTY WINDS WILL BE THE MAIN
WEATHER IMPACT THROUGH THE TAF PERIOD. GUSTS 20-25KT WILL BE
COMMON AT BOTH TERMINALS, FROM THE S-SW AT KBLH THIS AFTERNOON AND
FROM THE W-SW AT KIPL THIS EVENING. SPEEDS WILL RELAX OVERNIGHT
AND EARLY MORNING WHERE BRIEF PERIODS OF NEARLY CALM CONDITIONS
WILL EXIST. MOSTLY CLEAR SKIES WILL PREVAIL THOUGH THIS EVENING
BEFORE MID AND HIGH CLOUDS OVERSPREAD THE AREA HEADING INTO
SATURDAY.
FIRE WEATHER
RESIDUAL MOISTURE MAY SPARK A FEW SHOWERS AND STORMS THIS
AFTERNOON ACROSS SOUTH-CENTRAL AZ. RAIN CHANCES WILL EXPAND
WESTWARD THROUGH THIS WEEKEND, BECOMING FOCUSED OVER THE WESTERN
DISTRICTS SATURDAY AND SUNDAY. HOWEVER, THE CHANCES FOR WETTING
RAINS WILL REMAIN VERY LOW AT LESS THAN 10%. AFTERNOON MINIMUM
HUMIDITIES WILL RANGE FROM 7-15% ACROSS SOUTHEAST CA AND BETWEEN
20-35% FOR THE THE AZ DESERTS TODAY AND WILL LIKELY INCREASE ABOVE
20-25% AREAWIDE STARTING THIS WEEKEND. OVERNIGHT RECOVERIES WILL
RANGE FROM POOR ACROSS THE WESTERN DESERTS TO GOOD ACROSS THE
EASTERN DISTRICTS TONIGHT AND INCREASE TO GOOD AREAWIDE THIS
WEEKEND. WINDS WILL REMAIN ELEVATED OUT OF THE SOUTH TO SOUTHWEST,
WITH THE STRONGEST GUSTS IN SOUTHEAST CA AND ALONG THE LOWER
COLORADO RIVER VALLEY PEAKING BETWEEN 20-30 MPH THIS
AFTERNOON/EARLY EVENING. LIGHTER WINDS, GENERALLY AROUND 15 MPH OR
LESS WILL TRANSPIRE THIS WEEKEND.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...LOJERO
LONG TERM...SALERNO
AVIATION...BENEDICT
FIRE WEATHER...SALERNO/LOJERO
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