291
FXUS65 KTWC 112023
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
123 PM MST FRI SEP 11 2026
SYNOPSIS
A MORE ACTIVE DAY IS FORECAST ACROSS SOUTHEAST ARIZONA
TODAY WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS. MAIN
THREAT FROM STORMS TODAY WILL BE HEAVY RAIN AND LOCALIZED FLASH
FLOODING, ESPECIALLY ACROSS SANTA CRUZ COUNTY AND SOUTHWEST COCHISE
COUNTY. A MORE TYPICAL ISOLATED TO SCATTERED COVERAGE OF STORMS IS
FORECAST THIS WEEKEND INTO NEXT WEEK. DAILY HIGH TEMPERATURES WILL
FLUCTUATE BETWEEN NEAR NORMAL AND A FEW DEGREES BELOW NORMAL.
KEY MESSAGES
-ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON
MAINLY SOUTH AND EAST OF TUCSON CAPABLE OF PRODUCING POTENTIALLY
HEAVY RAINFALL.
-SLIGHT RISK (LEVEL 2 OF 4) TODAY FOR EXCESSIVE RAINFALL THAT MAY
LEAD TO LOCALIZED INSTANCES OF FLASH FLOODING IN FLOOD PRONE AREAS.
SENSITIVE LOW WATER CROSSINGS MAY BECOME IMPASSIBLE.
-ABOVE NORMAL MOISTURE FOR MID SEPTEMBER CONTINUES OVER THE WEEKEND
INTO EARLY NEXT WEEK RESULTING IN CONTINUED CHANCES FOR SHOWERS AND
STORMS AND A MARGINAL RISK (LEVEL 1 OF 4) FOR EXCESSIVE RAINFALL.
DISCUSSION
STORMS STARTED FORMING EARLY OVER HIGH TERRAIN AREAS
INCLUDING THE HUACHUCA AND WHITE MOUNTAINS AROUND 11 AM MST WHICH
WAS A BIT SOONER THAN CONVECTIVE ALLOWING MODELS SUGGESTED.
ADDITIONAL STORM ACTIVITY IS ANTICIPATED TO CONTINUE THIS AFTERNOON
AND EVENING WITH THE STRONGEST ACTIVITY MAINLY FOCUSED SOUTH AND
EAST OF TUCSON. THE PRIMARY CONCERNS WITH STORMS THIS AFTERNOON
CONTINUES TO BE HEAVY RAINFALL (RATES 1.0 TO 2.5 INCHES PER HOUR)
AND FREQUENT LIGHTNING. HOWEVER, GUSTY AND ERRATIC OUTFLOW WINDS TO
AROUND 45 MPH CANNOT BE RULED OUT WITH THE STRONGEST STORMS AS WELL.
HEAVY RAINFALL MAY RESULT IN ISOLATED INSTANCES OF FLASH FLOODING,
ESPECIALLY ACROSS SANTA CRUZ COUNTY, SOUTHWEST COCHISE COUNTY, AND
FAR SOUTHEAST PIMA COUNTY. PORTIONS OF EASTERN SANTA CRUZ COUNTY AND
SW COCHISE COUNTY HAS SEEN HEAVY RAIN OVER THE PAST 72 HOURS, SO THE
SOILS ARE WET, AND THE SAN PEDRO HAS HAD SOME INCREASED FLOW SEVERAL
DAYS AGO MAKING THEM MORE SUSCEPTIBLE TO SATURATION THIS AFTERNOON.
FLOWING WATER CAN BE EXPECTED IN NORMALLY DRY WASHES. SENSITIVE LOW
WATER CROSSINGS MAY BECOME IMPASSIBLE WITH SWIFT MOVING WATER.
REMEMBER TO REMAIN ALERT, AVOID DRIVING THROUGH FLOODED ROADS, AND
OBEY ROAD CLOSURES.
THE EXTENT OF SHOWERS AND STORMS TOMORROW WILL LARGELY DEPEND ON
HOW THE EVOLUTION OF STORM ACTIVITY THIS AFTERNOON AND EVENING.
BUT EVEN IF WE SEE LESS COVERAGE OF STORMS TOMORROW, SUFFICIENT
MOISTURE IN PLACE COULD AGAIN BE SUPPORTIVE OF HEAVY RAINFALL.
THE 11/12Z HREF DEPICTS A SLIGHT CHANCE (10-30%) FOR HEAVY RAIN
EXCEEDING 2 INCHES IN A 3 HOUR PERIOD ACROSS SANTA CRUZ COUNTY
AND SOUTHEAST PORTIONS OF PIMA COUNTY.
SUNDAY THROUGH THURSDAY MONSOONAL MOISTURE CONTINUES TO REMAIN IN
PLACE DAILY CHANCES (20-50%) FOR SHOWERS AND STORMS. OTHERWISE, HIGH
TEMPERATURES WILL REMAIN NEAR NORMAL THROUGH MONDAY AFTERNOON BEFORE
WE COOL OFF AND HIGHS SAG SLIGHTLY BELOW NORMAL.
AVIATION
VALID THRU 13/00Z.
SCT-BKN 6K-9K FT AGL. ISOLD TO SCT SHRA/TSRA MAINLY S AND E OF KTUS
THRU 12/02Z AND AGAIN AFT 12/21Z. ISOLD VSBY 1-3 MILES NR TS. LCLZD
TS OUTFLOW WINDS OF 30-40 KTS. OTRW, SFC WINDS WLY/NWLY AT 6-10 KTS
THRU 12/04Z AND AGAIN AFT 12/17Z. AT OTHER TIMES, SFC WINDS WILL
BE TERRAIN DRIVEN AND LESS THAN 10 KTS. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.
FIRE WEATHER
SCATTERED SHOWERS AND THUNDERSTORMS TODAY. A
MORE TYPICAL ISOLATED TO SCATTERED COVERAGE OF STORMS IS FORECAST
THIS WEEKEND INTO NEXT WEEK. HIGH TEMPERATURES WILL 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.
TWC WATCHES/WARNINGS/ADVISORIES
NONE.
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