832
FXUS65 KTWC 152112
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
212 PM MST TUE SEP 15 2026
SYNOPSIS
AN ACTIVE WEEK AHEAD WITH DAILY CHANCES OF SHOWERS AND
THUNDERSTORMS. ELEVATED PRECIPITATION CHANCES TODAY WITH A FLASH
FLOOD WATCH FOR PORTIONS OF SOUTHEAST ARIZONA. DAILY HIGH
TEMPERATURES WILL FLUCTUATE BETWEEN NEAR NORMAL AND A FEW DEGREES
BELOW NORMAL.
DISCUSSION
MUCH LESS COVERAGE OF SHOWER AND THUNDERSTORM ACTIVITY
AT THIS TIME TODAY COMPARED TO YESTERDAY, JUST A FEW ISOLATED
SHOWERS SO FAR AS OF THIS WRITING. HEAVY RAINFALL IS STILL A
CONCERN WITH ANY STRONGER STORMS THAT DEVELOP (MAINLY FROM
SELLS EASTWARD) LATER IN THE AFTERNOON. SLIGHT RISK FOR
EXCESSIVE RAINFALL CONTINUES FOR ACROSS SOUTHEAST ARIZONA.
OVERNIGHT INTO EARLY TOMORROW MORNING WE COULD SEE SOME
NOCTURNAL CONVECTION AS WELL, BUT CONFIDENCE IS LOWER IN THAT
COMING TO FRUITION. HOWEVER, IF IT DOES, HEAVY RAINFALL RATES
CONTINUE TO BE IN THE REALM OF POSSIBILITY WHICH IS CONCERNING
GIVEN THE AMOUNT OF RAIN RECEIVED OVER THE PAST SEVERAL DAYS. A
FLASH FLOOD WATCH GOES INTO EFFECT FOR ALL OF SOUTHEAST ARIZONA
STARTING AT 11 PM MST THIS EVENING.
BY MID MORNING TOMORROW, WE COULD SEE A BREAK IN ANY STORM ACTIVITY
THAT GETS GOING BEFORE AN UPTICK IN BOTH COVERAGE AND INTENSITY
DURING THE AFTERNOON AND EVENING HOURS AS A DISTURBANCE MOVES NORTH
AND EAST ACROSS SOUTHEAST ARIZONA. THE DYNAMICS ASSOCIATED WITH THIS
FEATURE WILL BRING A BETTER CHANCE OF MORE WIDESPREAD HEAVY RAINFALL
WITH HOURLY RAINFALL RATES OF 1"-2.5", WITH SOME AREAS POSSIBLY
SEEING OVER 3" OF RAIN. THUS, THE FLASH FLOOD WATCH CONTINUES UNTIL
11 PM MST TOMORROW EVENING. IN COORDINATION WITH SURROUNDING OFFICES
AND THE WEATHER PREDICTION CENTER THERE IS NOW A MODERATE RISK FOR
EXCESSIVE RAINFALL FOR PORTIONS OF PIMA, PINAL, AND GRAHAM COUNTIES
ON WEDNESDAY. IF THE DISTURBANCE MOVES ALONG A BIT FASTER, I
COULD SEE THE HEAVIEST RAINFALL AXIS SHIFT SOUTH A BIT INTO
CENTRAL/EASTERN PIMA AND PINAL COUNTIES. THE STRONGEST STORMS
MAY BE CAPABLE OF PRODUCING STRONG, GUSTY OUTFLOW WINDS AND
SMALL HAIL, BUT THIS IS STILL SECONDARY TO THE ELEVATED FLASH
FLOOD POTENTIAL GIVEN THE ENVIRONMENT.
THURSDAY: PRECIPITABLE WATER REMAINS ELEVATED FOR THIS TIME OF YEAR
WITH A SLIGHT RISK FOR EXCESSIVE RAINFALL CONTINUING EAST AND SOUTH
OF TUCSON. SHOWERS AND STORMS THAT DEVELOP WILL STILL HAVE THE
POTENTIAL FOR LOCALLY HEAVY RAINFALL, BUT WITHOUT THE DISTURBANCE
NEARBY THERE WILL BE A LACK OF FORCING TO HELP AID IN HIGHER
RAINFALL RATES LIKE WEDNESDAY.
FRIDAY THROUGH MONDAY: DRIER AIR FINALLY BEGINS TO FILTER INTO
SOUTHEAST ARIZONA AS FLOW ALOFT SHIFTS MORE WESTERLY/SOUTHWESTERLY.
THIS COULD HELP LIMIT THUNDERSTORM ACTIVITY SOMEWHAT AND KEEP
ACTIVITY MAINLY EAST AND SOUTH OF TUCSON. THE DRIER AIR WILL HELP
LESSEN THE THREAT FOR FLASH FLOODING, BUT BRIEF HEAVY RAINFALL AND
GUSTY OUTFLOW WINDS WILL STILL ACCOMPANY ANY STRONGER STORMS.
8 TO 14 DAY OUTLOOKS (TUE SEP 22 TO MON SEP 28)
TEMPERATURE: LEANING ABOVE NORMAL, 37-39% CHANCE
PRECIPITATION: LEANING ABOVE NORMAL, 40-44% CHANCE
AVIATION
VALID THRU 17/00Z.
SCT-BKN CLOUDS 7K-10K FT AGL WITH BKN LAYERS AOA 18K-20K FT AGL.
ISOLD-WDLY SCT -SHRA/-TSRA EXPECTED THRU MUCH OF THE VALID PD. AFTER
16/21Z, SCT-NUM COVERAGE OF SHRA/TSRA EXPECTED WITH HEAVY RAINFALL
RESULTING IN VISIBILITIES AS LOW AS 1 SM AT TIMES. GUSTY AND ERRATIC
OUTFLOW WINDS TO AROUND 35-45 KTS MAY ACCOMPANY STRONGEST TS. OUTSIDE
OF TS, SFC WINDS SLY/SWLY AT 7-12 KTS THRU 16/04Z BECOMING TERRAIN
DRIVEN UNDER 10 KTS THEREAFTER. AVIATION DISCUSSION NOT UPDATED FOR
TAF AMENDMENTS.
FIRE WEATHER
AN ACTIVE WEEK CONTINUES WITH DAILY CHANCES OF
SHOWERS AND STORMS CAPABLE OF PRODUCING HEAVY RAINFALL. HIGH
TEMPERATURES WILL FLUCTUATE BETWEEN NEAR NORMAL AND A FEW DEGREES
BELOW NORMAL. MIN RH VALUES MAINLY 20 TO 45 PERCENT IN THE VALLEYS
AND 35 TO 65 PERCENT IN THE MOUNTAINS OVER THE NEXT WEEK. RH
RECOVERIES WILL CONTINUE TO BE EXCELLENT OVERNIGHT. WINDS WILL
GENERALLY REMAIN LESS THAN 15 MPH AND TERRAIN DRIVEN. GUSTY AND
ERRATIC WINDS WILL ACCOMPANY THUNDERSTORMS.
HYDROLOGY
HEAVY RAINFALL OVER THE LAST 24 TO 72 HOURS HAS
RESULTED IN SATURATED SOILS AND FLOWING STREAMS/WASHES. THE
GILA RIVER AT DUNCAN, SAN FRANSISCO RIVER AT CLIFTON, AND THE
BRAWLEY WASH HAVE ALL SHOWN SIGNS OF SIGNIFICANT RISES OVER THE
PAST 24 HOURS. UPON COLLABORATION WITH THE COLORADO BASIN RIVER
FORECAST CENTER, AN ADDITIONAL 1 TO 2 INCHES COULD RESULT IN
ADDITIONAL RISES THAT COULD CAUSE THESE SITES TO EXCEED ACTION
STAGE AND APPROACH MINOR FLOOD STAGE. WILL BE MONITORING THESE
SITES CLOSELY FOR POTENTIAL IMPACTS.
TWC WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH FROM 11 PM MST THIS EVENING THROUGH 11 PM MST
WEDNESDAY EVENING FOR AZZ501>515.
DVS
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