647
FXUS65 KTWC 042031
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
131 PM MST FRI SEP 4 2026
SYNOPSIS
EXPECT ISOLATED TO SCATTERED THUNDERSTORMS EACH
AFTERNOON AND EVENING INTO EARLY NEXT WEEK, WITH A POTENTIALLY MORE
ACTIVE PERIOD LATER NEXT WEEK. THE MAIN THREAT WILL BE HEAVY
RAINFALL LEADING TO AREAS OF FLASH FLOODING. HIGH TEMPERATURES WILL
WILL FLUCTUATE BETWEEN NEAR NORMAL AND A FEW DEGREES BELOW NORMAL.
DISCUSSION
ISOLATED TO SCATTERED SHOWERS WITH A FEW THUNDERSTORMS
ARE ONGOING AS OF THIS WRITING SOUTH AND EAST OF TUCSON. HOWEVER,
THE STORMS FOR THE MOST PART ARE STRUGGLING TODAY AS SOME MODEST
WARMING/DRYING ALOFT IS RESULTING IN A BIT OF SUBSIDENCE/CAPPING,
KEEPING THE VERTICAL GROWTH OF THE STORMS IN CHECK. THERE JUST ISN'T
MUCH IN THE WAY OF LARGER SCALE LIFT OR FORCING TO HELP THINGS ALONG
TODAY. HOWEVER, WITH ADDITIONAL DAYTIME HEATING, STILL CAN'T RULE
OUT AN ISOLATED STRONGER STORM OR TWO THROUGH THE AFTERNOON WITH
MAIN CONCERN STILL BEING HEAVY RAIN AND ISOLATED FLASH FLOOD THREAT.
TUCSON WILL BE ON THE WESTERN PERIPHERY OF ANY ACTIVITY WITH
ANY STORMS DIMINISHING FAIRLY QUICKLY THIS EVENING AFTER SUNSET.
ABOVE NORMAL MOISTURE LEVELS WILL CONTINUE FOR EARLY SEPTEMBER
SATURDAY THROUGH MONDAY WITH PWAT VALUES MOSTLY IN THE 1 TO 1.5 INCH
RANGE ACROSS OUR FORECAST AREA WITH SOME MODEST ASSISTANCE FROM
HURRICANE MARIE WELL SOUTHWEST OF BAJA CALIFORNIA. WHILE MOISTURE
WILL CONTINUE TO REMAIN ELEVATED THIS WEEKEND, THERE REMAIN NO WELL
DEFINED TRIGGERS OR LIFT TO ENHANCE SHOWERS AND THUNDERSTORMS WITH
MODEST INSTABILITY LEVELS AS MID/UPPER LEVEL RIDGE AXIS NUDGES INTO
SE ARIZONA. EXPECT ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
EACH DAY, MAINLY TO THE SOUTH AND EAST OF TUCSON WHERE THERE IS
BETTER INSTABILITY. LOCALLY HEAVY RAINFALL WILL CONTINUE TO BE THE
MAIN THREAT.
THEREAFTER, FROM TUESDAY AND CONTINUING THROUGH THE REST OF THE WORK
WEEK, IT'S SHAPING UP TO BE A POTENTIALLY MORE ACTIVE PERIOD AS A
MORE ESTABLISHED LOWER TO MID LEVEL SOUTHEASTERLY FLOW SETS UP WITH
POTENTIAL TROPICAL INFLUENCE FROM A POSSIBLE SYSTEM NEAR SOUTHERN
BAJA. PLENTY OF TIME TO KEEP AN EYE ON THIS BUT NO SIGN OF MONSOON
2026 LETTING UP AS WE HEAD THROUGH THE NEXT WEEK TO 10 DAYS.
TEMPERATURES WILL BE WITHIN A COUPLE OF DEGREES OF NORMAL THROUGH
WEDNESDAY, THEN DROPPING TO BELOW NORMAL LEVELS LATE NEXT WEEK.
AVIATION
VALID THROUGH 06/00Z. SCT TO LOCALLY BKN CLOUDS 7-12K FT
AGL THROUGH MUCH OF THE FORECAST PERIOD, MAINLY KTUS EASTWARD.
ISOLATED TO SCATTERED TSRA/SHRA THRU 05/03Z THEN DIMINISHING
OVERNIGHT, WITH ISOLATED TO SCATTERED SHRA/TSRA MAINLY SOUTH AND
EAST OF KTUS AFT 05/19Z. NEAR ANY THUNDERSTORM WILL HAVE STRONG
GUSTY WINDS, HEAVY RAINFALL, AND BRIEF LOWERING OF CEILINGS. OUTSIDE
OF THUNDERSTORM WINDS, WINDS WILL BE SOUTH TO SOUTHWESTERLY THRU
05/06Z AND WEST TO NORTHWESTERLY 6-12 KTS AFT 05/18Z. LIGHT AND
TERRAIN DRIVEN AT OTHER TIMES. AVIATION DISCUSSION NOT UPDATED FOR
TAF AMENDMENTS.
FIRE WEATHER
EXPECT DAILY SCATTERED THUNDERSTORMS EACH AFTERNOON
AND EVENING INTO EARLY WEEK. THERE WILL BE SOME VARIATION IN
COVERAGE DAY TO DAY, BUT EXPECT THE BULK OF THE ACTIVITY FROM
CENTRAL PIMA COUNTY EASTWARD. HEAVY RAINFALL LEADING TO FLASH
FLOODING WILL BE THE MAIN THREAT. TEMPERATURES WILL BE AROUND NORMAL
TO A FEW DEGREES BELOW NORMAL INTO EARLY NEXT WEEK. MINIMUM RELATIVE
HUMIDITY VALUES MAINLY 20 TO 45 PERCENT IN THE VALLEYS AND 30 TO 60
PERCENT IN THE MOUNTAINS OVER THE NEXT WEEK. WINDS WILL GENERALLY
REMAIN LESS THAN 15 MPH AND TERRAIN DRIVEN THROUGH THE WEEK.
TWC WATCHES/WARNINGS/ADVISORIES
NONE.
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