148
FXUS65 KTWC 302023
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
123 PM MST WED SEP 30 2026
SYNOPSIS
THE STORM SYSTEM RESPONSIBLE FOR HEAVY RAIN ACROSS
SOUTHEAST ARIZONA THE PAST COUPLE DAYS WILL EXIT THE AREA THIS
AFTERNOON. A FEW LIGHT SHOWERS OR RUMBLES OF THUNDER CANNOT BE RULED
OUT MAINLY OVER THE WHITE MOUNTAINS AND CHIRICAHUA MOUNTAINS THIS
AFTERNOON. OTHERWISE, COOLER AND DRIER CONDITIONS WILL PREVAIL FOR
MUCH OF THE AREA THROUGH THE REMAINDER OF THE WEEK WITH BREEZY EAST
TO SOUTHEAST WINDS PICKING UP HEADING INTO THE WEEKEND.
DISCUSSION
THE FINAL DAY OF THE OFFICIAL MONSOON SEASON HAS
ARRIVED! THE MAIN WEATHER STORY TODAY IS GRADUAL CLEARING AS THE
STORM SYSTEM RESPONSIBLE FOR THE RECENT HEAVY RAINFALL EXITS THE
AREA EVENTUALLY EJECTING INTO THE SOUTHERN AND CENTRAL PLAINS.
STILL SOME RESIDUAL MOISTURE WRAPPING AROUND THE DISTURBANCE, SO WE
CAN'T RULE OUT A FEW LIGHT SHOWERS OR RUMBLES OF THUNDER OVER THE
WHITE MOUNTAINS AND/OR CHIRICAHUAS THIS AFTERNON. HOWEVER, WITH BEST
FORCING ASSOCIATED WITH THE UPPER LOW NOW TO OUR EAST AND WITH A
COOLER, DRIER AIRMASS MOVING IN BEHIND THE DISTURBANCE THE THREAT
FOR HEAVY RAINFALL HAS ENDED. THUS, ANYTHING THAT DEVELOPS WOULD BE
LIGHT/SHOWERY IN NATURE, ASSOCIATED WITH RESIDUAL MOISTURE, AND
WOULD BE FORCED FROM THE TERRAIN.
HEADING INTO THE WEEKEND WE'LL SEE A DRYING TREND TAKE SHAPE AS A
RIDGE OF HIGH PRESSURE GRADUALLY BUILDS ACROSS THE DESERT SOUTHWEST
AND INTO THE GREAT BASIN. TEMPERATURES WILL REMAIN BELOW NORMAL BY
10-15 DEGREES FOR EARLY OCTOBER WITH AN UPTICK IN SOUTHEAST
BREEZINESS OVER THE WEEKEND AS A PRESSURE GRADIENT BUILDS FROM
HIGHER PRESSURE SLIDING DOWN THE FRONT RANGE OF THE ROCKIES. IN
FACT, THE LATEST NBM PROBABILITY FOR SUSTAINED WINDS IN EXCESS OF 25
MPH ACROSS THE VALLEYS EAST OF TUCSON IS GENERALLY 30 TO 50 PERCENT
FRIDAY INTO EARLY NEXT WEEK, WITH THE STRONGEST PROBABILITIES SUNDAY
AND MONDAY.
AVIATION
VALID THRU 02/00Z.
SCT-BKN 4-6K FT AGL BKN-OVC 9-12K FT AGL. DECREASING CLOUDINESS
EXPECTED GRADUALLY FROM WEST TO EAST THRU THE AFTERNOON. CAN'T RULE
OUT A FEW STRAY -SHRA/-TSRA EAST/NORTHEAST OF A KOLS TO KE77 LINE,
BUT CONFIDENCE IS LOW. SFC WINDS WLY/NWLY AT 8-12 KTS WITH GUSTS UP
TO 22 KTS THRU 01/03Z BECOMING LIGHT AND TERRAIN DRIVEN THRU
01/17Z. TOMORROW, SFC WINDS ELY/NELY AT 8-12 KTS. AVIATION
DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
FIRE WEATHER
THE UPPER-LEVEL DISTURBANCE RESPONSIBLE FOR PRODUCING
WIDESPREAD HEAVY RAINFALL ACROSS SOUTHEAST ARIZONA TUESDAY WILL EXIT
THE AREA TODAY INTO NEW MEXICO. THERE IS ENOUGH RESIDUAL MOISTURE
AROUND FOR THIS SYSTEM TO PRODUCE A FEW LIGHT RAIN SHOWERS ON ITS
WAY OUT OVER THE WHITE MOUNTAINS AND CHIRICAHUAS, BUT CONFIDENCE IS
LOW. OTHERWISE, A RIDGE OF HIGH PRESSURE WILL TAKE UP RESIDENCE
ACROSS THE REGION THE SECOND HALF OF THE WEEK. ALTHOUGH THIS WILL
PROVIDE DRY CONDITIONS, IT WILL ALSO RESULT IN BREEZY EAST TO
SOUTHEAST WINDS FRIDAY INTO EARLY NEXT WEEK. AFTERNOON HIGH
TEMPERATURES WILL BE 10-15 DEGREES BELOW NORMAL AGAIN TODAY, WARMING
TO ONLY A FEW DEGREES BELOW NORMAL THIS WEEKEND. MINIMUM RH VALUES
35-55 PERCENT IN VALLEY LOCATIONS AND 50-75 PERCENT IN THE MOUNTAINS
TODAY, GENERALLY LOWERING TO 15-25 PERCENT THE SECOND HALF OF THE
WEEK AS DRIER AIR MOVES INTO THE REGION. 20-FOOT WINDS WILL BE LESS
THAN 15 MPH INTO THURSDAY, THEN GUSTY EAST TO SOUTHEAST WINDS FRIDAY
THROUGH EARLY NEXT WEEK.
HYDROLOGY
STILL KEEPING A CLOSE EYE ON ELEVATED FLOWS
OBSERVED ON THE GILA RIVER NEAR DUNCAN AND SOLOMON AS RUNOFF
CONTINUES FROM HEAVY RAINFALL OVER THE LAST COUPLE DAYS. THE
GILA RIVER NEAR DUNCAN IS FORECAST TO REMAIN NEAR ACTION STAGE
THROUGH LATE THIS EVENING. DOWNSTREAM NEAR SOLOMON, THE GILA
RIVER CRESTED AT 22.6 FEET (MODERATE FLOOD STAGE) AROUND 7 AM
MST THIS MORNING BUT IS FORECAST TO REMAIN ABOVE FLOOD STAGE
THROUGH 5 PM THIS AFTERNOON. DOWNSTREAM IMPACTS COULD EVENTUALLY
REACH CALVA WITH A SIGNIFICANT RISE IN THE FORECAST POTENTIALLY
ABOVE ACTION STAGE EARLY TOMORROW MORNING. BUT FOR NOW, WE
CONTINUE TO COLLABORATE WITH THE COLORADO BASIN RIVER FORECAST
CENTER (CBRFC) AND LOCAL EMERGENCY MANAGEMENT TO CLOSELY MONITOR
THE SITUATION AND ASSOCIATED IMPACTS.
TWC WATCHES/WARNINGS/ADVISORIES
NONE.
DVS
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