196
FXUS65 KPSR 020830
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
130 AM MST WED SEP 2 2026
KEY MESSAGES
- TEMPERATURES SHOULD REMAIN IN A NEAR TO BELOW NORMAL CATEGORY
FOR THE FIRST WEEK OF SEPTEMBER, RESULTING IN WIDESPREAD MINOR
HEAT RISK AND LOCALIZED AREAS OF MODERATE HEAT RISK.
- ISOLATED SHOWERS AND STORMS WILL BE POSSIBLE OVER THE HIGHER
TERRAIN OF EASTERN AND SOUTHEASTERN AZ TODAY AND THURSDAY
- TROPICAL MOISTURE WILL ARRIVE INTO THE REGION LATE THURSDAY INTO
FRIDAY AND PERSIST THROUGH MUCH OF THE WEEKEND, RESULTING IN A
CHANCE OF HEAVY RAINFALL IN SOME LOCATIONS.
SHORT TERM /TODAY THROUGH FRIDAY/
LATEST MID-LVL WV IMAGERY AND 500 MB STREAMLINE ANALYSIS REVEALS A
DEEP TROUGH OF LOW PRESSURE ENCOMPASSING MUCH OF THE WEST COAST
WHILE A RIDGE OF HIGH PRESSURE EXTENDS FROM THE SOUTHERN PLAINS INTO
THE SOUTHEASTERN U.S. OUR FORECAST AREA IS SITUATED BETWEEN BOTH OF
THESE FEATURES UNDER A PROMINENT FETCH OF SW FLOW ALOFT. MEANWHILE,
TS MARIE HAS FORMED OVER THE E PACIFIC, WELL SOUTH OF THE TIP OF
THE BAJA PENINSULA. MOISTURE ASSOCIATED WITH THIS STORM IS ALREADY
BEING ADVECTED WELL OUT AHEAD OF THE MAIN CIRCULATION INTO N
SONORA MX AS EVIDENT IN WV IMAGERY. WHILE THE STORM ITSELF IS
EXPECTED TO REMAIN OFFSHORE AND PROGRESS NW INTO OPEN WATERS OVER
THE COMING DAYS, WE WILL BEGIN TO SEE AN INCREASE IN OVERALL
MOISTURE BEGINNING IN SOUTHERN AZ THIS AFTERNOON AND EVENTUALLY
ENCROACHING ON SOUTHCENTRAL AZ BY THURSDAY INTO FRIDAY. THE EPS
AND GEFS MEAN PWAT VALUES AT KPHX SHOW A GRADUAL RISE FROM AROUND
1.4-1.5" TODAY TO 1.7-1.8" BY FRIDAY WITH A FEW MEMBERS REACHING
2.0". AS MOISTURE ADVECTION INCREASES EACH DAY, RAIN CHANCES WILL
FOLLOW SUIT. LATEST NBM POPS ARE PICKING UP ON WIDELY SCATTERED
SHOWER AND STORM ACTIVITY ACROSS SOUTHEASTERN AZ THIS AFTERNOON,
MAINLY IN THE TWC FORECAST AREA. ON THURSDAY, A MUCH BETTER PUSH
OF MOISTURE IS ANTICIPATED WHICH WILL BRING CHANCES FOR SHOWERS
AND STORMS INTO SOUTHCENTRAL AZ. CURRENTLY POPS ARE AROUND 30-60%
LATE THURSDAY INTO FRIDAY WITH CHANCES TAPERING DOWN INTO FRIDAY
AFTERNOON. THERE WILL LIKELY BE A SHARP GRADIENT IN POPS FROM W TO
E ON THURSDAY AND FRIDAY AS MUCH DRIER AIR ADVECTS INTO SE
CALIFORNIA AND SW ARIZONA. THEREFORE, RAIN CHANCES ACROSS THE
WESTERN HALF OF THE FORECAST AREA WILL BE SLIM TO NONE INITIALLY.
DUE TO THE PRESENCE OF TROUGHING TO OUR WEST AND A SEASONABLE 500
MB HGHT FIELD AROUND 587-590 DAM, TEMPERATURES WILL REMAIN WITHIN
A DEGREE OR TWO OF DAILY NORMALS THROUGH THE END OF THIS WEEK.
LOWER DESERT HIGHS WILL GENERALLY RANGE FROM THE UPPER 90S TO
AROUND 105 DEGREES EACH AFTERNOON, FOLLOWING MORNING LOWS FROM THE
UPPER 70S TO MIDDLE 80S. THE WEST COAST TROUGH WILL ALSO INDUCE A
COMPACT 700-500 MB HGHT GRADIENT OVER SOUTHEAST CA AND WESTERN AZ
BEGINNING TODAY WHICH WILL LEAD TO BREEZY CONDITIONS ACROSS THE
IMPERIAL AND LOWER COLORADO RIVER VALLEYS. GUSTS COULD REACH
UPWARDS OF 25-30 MPH IN THE AFOREMENTIONED AREAS AND POTENTIALLY
AS HIGH AS 40 MPH IN FAR SW IMPERIAL COUNTY.
LONG TERM /SATURDAY THROUGH TUESDAY/
THE FORECAST BECOMES MORE UNCERTAIN HEADING INTO THIS WEEKEND,
BUT THE GENERAL MODEL CONSENSUS IS SHOWING THE SUBTROPICAL RIDGE
OVER THE SOUTHEAST U.S. RETROGRADING WEST INTO THE SOUTHERN
PLAINS. THE WESTERN PERIPHERY OF THE RIDGE WILL LIKELY NOSE INTO
EASTERN AZ ON SATURDAY. IF THIS OCCURS, THEN THE SUBTROPICAL JET
WILL LIKELY SHIFT FARTHER WEST, SETTING UP BETTER MOISTURE
ADVECTION OVER SOCAL AND WESTERN AZ. THIS SCENARIO IS CURRENTLY
BEING REFLECTED WITHIN THE NBM SHOWING A WESTWARD PROGRESSION OF
POPS FROM SOUTHCENTRAL AZ EARLY SATURDAY INTO SOUTHWEST AZ AND
SOUTHEAST CA LATE SATURDAY INTO SUNDAY. DUE TO AN OVERALL INCREASE
IN MOISTURE AND EXTENSIVE CLOUD COVER THIS WEEKEND, IT IS LIKELY
WE WILL SEE LOWER INSTABILITY WHICH COULD LIMIT CONVECTION AND
KEEP THE THREAT OF HEAVY RAINFALL AT A MINIMUM IN OUR FORECAST
REGION WITH BETTER PROSPECTS OF HEAVY RAIN AND FLASH FLOODING OVER
SOCAL AND S NV. THERE IS STILL PLENTY OF TIME FOR THINGS TO
CHANGE AND WE WILL LIKELY HAVE TO WAIT UNTIL WE ARE WITHIN THE
HIGH-RES WINDOW FOR THIS WEEKEND'S FORECAST TO BECOME MORE CLEAR.
SIMILAR TO RAIN CHANCES, THERE IS ALSO A HIGH UNCERTAINTY IN THE
TEMPERATURE FORECAST BY THIS WEEKEND AS INDICATED BY LARGE (5-8
DEGREE) SPREADS WITHIN THE NBM INNER QUARTILE RANGE, ESPECIALLY ON
SATURDAY. THIS IS LIKELY DUE TO THE STRENGTH OF THE RIDGE AND HOW
MUCH CLOUD COVER WILL OCCUR OVER THE REGION. IT IS LIKELY THAT
SATURDAY WILL BE THE COOLEST DAY WITH HIGHS IN THE LOWER DESERTS
MAINLY IN THE MID TO UPPER 90S. HOWEVER, AS RIDGING ALOFT CAUSES
AN OVERALL INCREASE IN MID LVL HGHTS/THICKNESS, TEMPERATURES MAY
WARM TO NEAR OR EVEN SLIGHTLY ABOVE NORMAL FROM SUNDAY INTO EARLY
NEXT WEEK.
AVIATION
UPDATED AT 0520Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
NO MAJOR AVIATION CONCERNS ARE EXPECTED THROUGH WEDNESDAY
AFTERNOON. WINDS WILL FOLLOW LIGHT FAMILIAR DIURNAL TRENDS WITH
PERIODS OF VRB CONDITIONS OVERNIGHT AND SOME OCCASIONAL AFTERNOON
GUSTS IN THE MID TEENS TO AROUND 20 KT. A SLOWER-THAN-USUAL
TRANSITION FROM EAST TO WEST MAY PRODUCE A FEW HOURS OF SOUTHERLY
CROSS WINDS AT KPHX AND KDVT, WITH PERHAPS A WINDOW OF DIRECTIONS
160V230 BEFORE WESTERLY FLOW TAKES OVER. THERE ARE HINTS OF TS
ACTIVITY MOVING WITHIN THE VICINITY OF THE TERMINALS DURING THE
LATE AFTERNOON TO EARLY EVENING HOURS, BUT NO MENTION IS INCLUDED
IN THE TAF AT THIS TIME AS RAIN CHANCES ARE TOO LOW ~10%.
GENERALLY CLEAR SKIES TONIGHT WILL GIVE WAY TO A FEW LOW- LEVEL
CLOUDS DURING THE BACK HALF OF THE PERIOD.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION CONCERNS ARE EXPECTED DURING THE NEXT 24 HOURS.
WINDS WILL FAVOR A WESTERLY COMPONENT AT KIPL, WHILE SOUTH-
SOUTHWESTERLY TO SOUTHWESTERLY FLOW WILL BE COMMON AT KBLH. BREEZY
CONDITIONS WITH GUSTS UPWARDS OF 20-25 KT WILL DEVELOP AT EACH
TERMINAL DURING THE BACK HALF OF THE FORECAST WINDOW. SKIES WILL
BE MOSTLY CLEAR THROUGH WEDNESDAY EVENING.
FIRE WEATHER
DRIER CONDITIONS WILL PREVAIL THROUGH THURSDAY WITH ONLY ISOLATED
CHANCES FOR SHOWERS AND THUNDERSTORMS MOSTLY RELEGATED TO THE HIGHER
TERRAIN OF SOUTHCENTRAL AND SOUTHEASTERN AZ. BETTER CHANCES FOR
WETTING RAINS RETURN TO THE REGION LATE THIS WEEK INTO THIS WEEKEND.
AFTERNOON MINIMUM HUMIDITIES WILL RANGE FROM 7-15% ACROSS SOUTHEAST
CA AND BETWEEN 15-35% FOR MUCH OF SOUTHERN AZ THROUGH THE NEXT FEW
DAYS AND WILL LIKELY INCREASE ABOVE 25% AREAWIDE THIS WEEKEND.
OVERNIGHT RECOVERIES WILL RANGE FROM POOR ACROSS THE WESTERN DESERTS
AND GOOD TO EXCELLENT ACROSS THE EASTERN DISTRICTS. DAYTIME 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 DURING THE AFTERNOON/EARLY EVENING.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...SALERNO
LONG TERM...SALERNO
AVIATION...RW
FIRE WEATHER...WHITTOCK/SALERNO
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