849
FXUS65 KTWC 121702
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
1002 AM MST SAT SEP 12 2026
SYNOPSIS
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.
UPDATE
FORECAST FOCUS TODAY WILL BE ISOLATED TO SCATTERED
STORMS POSSIBLE AGAIN PRIMARILY SOUTH AND WEST OF TUCSON. GIVEN
PRECIPITABLE WATER VALUES BETWEEN 1 AND 2 INCHES (1.3 ACROSS
EASTERN AREAS, 1.5 INCHES IN THE TUCSON METRO, AND 1.8 INCHES
ACROSS WESTERN PIMA COUNTY) HEAVY RAINFALL WILL AGAIN BE THE
PRIMARY THREAT WITH ANY STORMS THAT FORM. SECONDARILY, CANNOT
RULE OUT GUSTY OUTFLOW WINDS AND/OR SMALL HAIL WITH THE
STRONGEST STORMS.
PLENTY OF INSTABILITY IN PLACE (1500-2500 J/KG MLCAPE) HELPS ADD TO
MY CONFIDENCE OF THERE BEING SOME LEVEL OF STORM ACTIVITY.
HOWEVER, THE BIG QUESTION IS HOW WILL THE COVERAGE COMPARE TO
YESTERDAY? CAN THE AVAILABLE INSTABILITY BE UTILIZED?
YESTERDAY, THE HREF AND REFS MEMBERS APPEARED TO OVERDO THE
STORM COVERAGE AND INTENSITY. TODAY, LOOKING LIKE COVERAGE WILL
END UP BEING ISOLATED IN NATURE GIVEN THE LACK OF BROAD SCALE
DYNAMIC FORCING OUTSIDE OF NORMAL TERRAIN FORCING. WITH THE
LACK OF SHEAR AND SLOWER STORM MOTIONS MY CONFIDENCE IN STORM
COVERAGE BECOMING MORE WIDESPREAD DURING THE AFTERNOON IS LOWER
COMPARED TO YESTERDAY, BUT OUTFLOWS FROM STORMS THAT DO GET
GOING COULD ALWAYS AID AS A LIFTING MECHANISM LATER IN THE DAY.
WE'RE ALREADY SEEING SOME CUMULUS GOING UP ACROSS THE AREA, AND
GIVEN THE IMPRESSIVE MOISTURE PROFILE FOR THIS TIME OF YEAR IT WOULD
BE NO SURPRISE IF WE HAVE AN EARLIER START TO STORM ACTIVITY LIKE
YESTERDAY BEFORE NOON MST. THE HREF DEPICTS A SLIGHT CHANCE (10%)
FOR EXCEEDING 3 INCHES THIS AFTERNOON PINPOINTING AREAS SOUTH AND
WEST OF TUCSON. OVERALL, MY THINKING IS THAT WE HAVE THE INGREDIENTS
FOR LOCALIZED FLASH FLOODING CONCERNS AGAIN TODAY FOCUSED MAINLY
SOUTH AND WEST OF TUCSON ACROSS SANTA CRUZ COUNTY AND AREAS AROUND
THE BABOQUIVARI MOUNTAINS.
PREV DISCUSSION
/ISSUED 300 AM MST SAT SEP 12 2026/
PARTLY TO MOSTLY CLOUDY CONDITIONS PREVAILED EARLY THIS MORNING WITH
A FEW STORMS OCCURRING WEST OF PICACHO PEAK. THIS WEEKEND WILL SEE
ISOLATED TO SCATTERED THUNDERSTORMS WITH THE USUAL THREATS, GUSTY
OUTFLOW WINDS AND BRIEF HEAVY RAIN.
MONDAY, AT THIS TIME, LOOKS TO BE A BIT MORE ACTIVE POSSIBLY
ASSOCIATED WITH A WEAK DISTURBANCE MOVING NORTH ACROSS THE AREA.
QPF IS TRENDING UP WITH WPC PLACING PORTIONS OF THE FORECAST AREA
UNDER SLIGHT RISK FOR EXCESSIVE RAINFALL WITH THE POTENTIAL FOR
STRONGER STORMS PRODUCING RAINFALL RATES OF 1-2"/HR LEADING TO THE
INCREASED RISK OF LOCALIZED FLASH FLOODING. TIME WILL TELL AS ITS
DIFFICULT TO TIME DISTURBANCES THIS FAR OUT.
WILL KEEP DAILY THREAT OF AFTERNOON/EVENING STORMS TUESDAY THRU
FRIDAY WITH DAY-TO-DAY CHANGES IN AREAL COVERAGE.
HIGH TEMPERATURES WILL MOSTLY BE AROUND NORMAL FOR THE NEXT 7 DAYS.
AVIATION
VALID THRU 13/12Z.
SCT-BKN 6K-9K FT AGL. ISOLD -SHRA/TS W OF KTUS TIL 12/15Z THEN SCT
SHRA/TSRA BTWN 12/18Z TO 13/04Z. SFC WINDS TERRAIN DRIVEN AND LESS
THAN 10 KTS TIL 12/17Z AND AGAIN AFT 13/05Z. AT OTHER TIMES,
WLY/NWLY AT 6-10 KTS AVIATION DISCUSSION NOT UPDATED FOR TAF
AMENDMENTS.
FIRE WEATHER
A 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.
DVS
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