064
FXUS65 KTWC 250906
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
206 AM MST TUE AUG 25 2026
SYNOPSIS
A VERY LOW GRADE MONSOON PATTERN THROUGH WEDNESDAY WITH
LIMITED (10 PERCENT OR LESS) STORM CHANCES FOR MOST LOCALES. STORM
CHANCES NUDGE HIGHER STARTING THURSDAY, THEN RETURN TO MORE TYPICAL
LEVELS FRIDAY AND THROUGH THE WEEKEND. HIGH TEMPERATURES WILL REMAIN
WELL ABOVE NORMAL THROUGH THE WEEK WITH AN EXTREME HEAT WARNING IN
EFFECT FOR MUCH OF SOUTHEAST ARIZONA.
DISCUSSION
MOSTLY CLEAR SKIES ACROSS SOUTHEAST ARIZONA THIS
MORNING AS THE AREA IS UNDER THE INFLUENCE OF STRONG HIGH PRESSURE
ALOFT OVER NEW MEXICO. LATEST GOES TOTAL PRECIPITABLE WATER SHOWS
QUITE A BIT OF DRYING WITH PWAT VALUES DOWN TO 0.75" TO 1 INCH FROM
TUCSON EASTWARD, THOUGH LOCALES WEST OF TUCSON ARE HANGING ONTO A
HIGHER MOISTURE LEVELS WITH PWATS OF 1.25" TO 1.5" OVER THE T.O.
NATION AND WESTERN DESERTS. GIVEN THE DRIER CONDITIONS FOR MUCH OF
THE AREA AND SUBSIDENCE FROM THE HIGH ALOFT, WE'RE EXPECTING ANOTHER
DOWN DAY FOR STORM ACTIVITY, THOUGH WE CAN'T RULE OUT A ROGUE WEAK
STORM OR TWO ACROSS SANTA CRUZ OR SOUTH CENTRAL PIMA COUNTY WHERE
INSTABILITY AND MOISTURE LEVELS ARE BETTER ALIGNED.
THE HIGH PRESSURE ALOFT ON WEDNESDAY NUDGES WEST ALONG THE AZ/NM
BORDER WITH ANOTHER DAY OF VERY LIMITED STORM ACTIVITY EXPECTED
GIVEN THE SUBSIDENCE FROM THE HIGH AND CONTINUED OVERALL LACK OF
MOISTURE. ONCE AGAIN, SANTA CRUZ COUNTY INTO SOUTH CENTRAL PIMA
COUNT WOULD BE THE FAVORED REGION FOR ANY STORMS.
FOR THURSDAY, NOT MUCH MOVEMENT ON THE HIGH NEAR THE AZ/NM BORDER.
MOISTURE LEVELS START TICKING HIGHER TO SUPPORT 10 TO 30 PERCENT
STORM CHANCES FROM TUCSON SOUTH AND EASTWARD, THOUGH THE HIGHEST
CHANCES WILL BE ALONG THE INT'L BORDER AND MOUNTAINS.
A TRANSITION BACK TO A MORE TYPICAL MONSOON PATTERN WILL OCCUR
FRIDAY, CONTINUING THIS WEEKEND INTO EARLY NEXT WEEK AS THE HIGH
ALOFT MOVES EAST, PUTTING SOUTHEAST ARIZONA IN A MORE FAVORABLE
REGION FOR DAILY MONSOONAL ACTIVITY WITH EAST TO SOUTHEAST FLOW AS
PWATS INCREASE TO ABOVE NORMAL LEVELS THIS WEEKEND. DAILY STORM
CHANCES DURING THIS PERIOD WILL TYPICALLY BE IN THE 20 TO 60 PERCENT
RANGE WITH THE USUAL IMPACTS INCLUDING GUSTY WINDS AND AREAS OF
FLASH FLOODING.
THE EXTREME HEAT WARNING REMAINS IN EFFECT THROUGH SATURDAY WITH
HIGHS 6 TO 10 DEGREES ABOVE NORMAL AND THE HEAT PEAKING TODAY
THROUGH FRIDAY.
AVIATION
VALID THROUGH 26/12Z.
SKC-SCT CLOUDS MAINLY 10-13K FT AGL THROUGH THE FORECAST PERIOD WITH
THE MOST LIKELY PERIOD FOR CLOUDS BEING 25/21Z TO 26/03Z. SFC WINDS
LIGHT AND TERRAIN DRIVEN THROUGH 25/18Z, THEN THIS AFTERNOON AND
EARLY EVENING MOSTLY W/NW AROUND 5-10KTS (WITH THE EXCEPTION OF KDUG
TERMINAL WHERE EASTERLY COMPONENT REMAINS). A FEW HIGHER GUSTS TO
AROUND 15-18 KTS THIS AFTERNOON AS WELL. SFC WINDS BECOME LIGHT AND
TERRAIN DRIVEN AFT 26/04Z. AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.
FIRE WEATHER
VERY ISOLATED THUNDERSTORMS (10 PERCENT OR LESS
CHANCE) FOR MOST LOCALES THROUGH WEDNESDAY, THOUGH SLIGHTLY HIGHER
CHANCES ALONG THE IMMEDIATE INT'L BORDER AND WHITE MOUNTAIN REGION.
THEREAFTER, STORM CHANCES NUDGE HIGHER TO AROUND 10 TO 30 PERCENT
THURSDAY AND TO MORE TYPICAL LEVELS OF 20 TO 60 PERCENT FRIDAY INTO
EARLY NEXT WEEK. TEMPERATURES WILL REMAIN WELL ABOVE NORMAL THROUGH
MOST OF THE WEEK WITH A COOLING TREND THIS WEEKEND INTO EARLY NEXT
WEEK. MINIMUM RELATIVE HUMIDITY VALUES MAINLY 10 TO 20 PERCENT IN
THE VALLEYS AND 20 TO 30 PERCENT IN THE MOUNTAINS THROUGH FRIDAY.
MINIMUM RH VALUES INCREASE TO 20 TO 30 PERCENT FRIDAY IN VALLEYS AND
30-50 PERCENT IN THE MOUNTAINS, WITH EVEN HIGHER LEVELS OF 30 TO 40
PERCENT IN VALLEYS AND 40 TO 50 PERCENT IN THE MOUNTAINS. WINDS WILL
GENERALLY REMAIN LESS THAN 15 MPH AND TERRAIN DRIVEN THROUGH THE
WEEK.
TWC WATCHES/WARNINGS/ADVISORIES
EXTREME HEAT WARNING UNTIL 8 PM MST SATURDAY FOR AZZ501-502-
504>506-509.
EXTREME HEAT WARNING FROM 10 AM THIS MORNING TO 8 PM MST SATURDAY
FOR AZZ503-507-508.
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