172
FXUS65 KTWC 041614
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
914 AM MST FRI SEP 4 2026
SYNOPSIS
EXPECT SCATTERED THUNDERSTORMS EACH AFTERNOON AND EVENING
THROUGH THE WEEKEND AS TROPICAL MOISTURE MOVES IN. THE MAIN
THREAT WILL BE HEAVY RAINFALL LEADING TO AREAS OF FLASH
FLOODING. HIGH TEMPERATURE WILL WILL FLUCTUATE BETWEEN NORMAL
AND A FEW DEGREES BELOW NORMAL.
UPDATE
CLEAR SKIES THIS MORNING WEST OF TUCSON WITH GENERALLY
PARTLY CLOUDY SKIES EAST OF TUCSON. PLENTY OF LOWER LEVEL MOISTURE
OUT THERE WITH SURFACE DEWPOINTS IN THE 60S FOR ALL VALLEY LOCATIONS
AND PWATS RANGING FROM 1.1 INCHES OUT WEST TO AROUND 1.5 INCHES NEAR
THE NM BORDER. THE DRIER AIR ALOFT WILL PRECLUDE CONVECTION OVER THE
WESTERN DESERTS TODAY, BUT ENOUGH MOISTURE AND INSTABILITY FOR
SCATTERED SHOWERS AND THUNDERSTORMS MAINLY FROM THE TUCSON AREA
EASTWARD. IN FACT, WE'RE STARTING TO SEE SOME CUMULUS BUILD-UPS ON
THE LATEST VISIBLE SATELLITE IMAGERY WITH STORMS GETTING AN EARLIER
START TODAY. 12Z HREF/REFS FOCUSING A BIT MORE ON WESTERN
GRAHAM/WESTERN COCHISE COUNTIES FOR A BIT MORE CLUSTERING/COVERAGE.
WITH THAT SAID, GIVEN LACK OF GOOD FORCING ALOFT FOR STORMS, THEY
WILL MOSTLY BE DEPENDENT ON SURFACE HEATING. MAIN CONCERN IS THAT
STORMS WILL BE EFFICIENT RAIN PRODUCERS WITH THE STRONGER STORMS
DROPPING OVER 1 INCH PER HOUR RESULTING IN ISOLATED FLASH FLOODING
POTENTIAL. NO FLOOD WATCH HEADLINES PLANNED TODAY GIVEN THE THINKING
THAT FLASH FLOODING THREAT STAYS MORE ON THE ISOLATED SIDE.
OTHERWISE, GUSTY WINDS OF 30 TO 40 MPH POSSIBLE WITH THE STRONGER
STORMS. SEE PREVIOUS DISCUSSION BELOW FOR ADDITIONAL INFORMATION.
DISCUSSION
CURRENTLY THERE IS LINGERING CLOUDS WITH A FEW SHOWERS ALONG
THE AZ/NM BORDER AND SOUTH OF THE INTERNATIONAL BORDER, WITH
SOME OF THE STRONGER STORMS HAVING A LIGHTNING STRIKE OR TWO.
THE LATEST CAMS HAVE LITTLE TO ISOLATED ACTIVITY THE REST OF
TONIGHT.
LOOKING INTO TODAY, THE MOISTURE IS STILL IN PLACE WITH A WEST
TO EAST GRADIENT OF PWS OF 1.0 TO 1.7 INCHES WITH THE HIGHEST
VALUES TUCSON EASTWARD. THE UPPER LEVEL PATTERN HAS A LOW
PRESSURE SYSTEM TO THE NW AND HURRICANE MARIE TO THE SW OF THE
AREA AND HIGH PRESSURE TO THE WEST KEEPS THE SOUTH TO SOUTHWEST
FLOW ALOFT. THIS IS AREA IS THE CAMS ARE HIGHLIGHTING FOR
ACTIVITY THIS AFTERNOON AND EVENING. THIS LINES UP WITH THE
SLIGHT RISK OF FLASH FLOODING FOCUSING IN ON AREAS EAST OF
TUCSON. SIMILAR TO YESTERDAY, STORMS WILL BE EFFICIENT RAINERS
WITH ACCUMULATIONS OF ISOLATED 1 TO 2 INCHES OF RAINFALL
POSSIBLE WITH ANY STORM THAT COULD LEAD TO FLASH FLOODING. AREAS
THAT HAD RAINFALL TODAY WILL SEE QUICKER RESPONSES IN CREEKS,
RIVERS, AND WASHES, ESPECIALLY IN GRAHAM, GREENLEE, AND COCHISE
COUNTIES.
AS THE LOW PRESSURE SYSTEM MOVES TO CUT OFF FROM THE MAIN FLOW
AND HURRICANE MARIE MOVES WEST, MOISTURE CONTINUES TO MOVE IN,
WITH THE BULK OF THE MOISTURE TO THE NORTH OF THE AREA, HOWEVER
EXPECTING SIMILAR PWS SIMILAR IN CURRENT VALUES CONTINUE INTO
EARLY NEXT WEEK. THIS KEEPS BROAD SLIGHT CHANCES (30-50%) FOR
AREAS SOUTH AND EAST OF TUCSON.
TEMPERATURES WILL BE HOVERING NEAR NORMAL TO SLIGHTLY BELOW
NORMAL THROUGH THE FORECAST PERIOD.
AVIATION
VALID THROUGH 05/12Z.
SCT-BKN CLOUDS 7-12K FT AGL THROUGH MUCH OF THE FORECAST
PERIOD, MAINLY KTUS EASTWARD. SCATTERED TSRA/SHRA THIS
AFTERNOON AND LASTING THROUGH THE OVERNIGHT PERIOD. ALTHOUGH THE
OVERNIGHT TSRA/SHRA ACTIVITY WILL BE MORE ISOLATED. 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 5-10 KTS FROM 04/15Z THRU 05/06Z
AND WEST TO NORTHWESTERLY 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
TODAY INTO EARLY NEXT 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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