410
FXUS65 KTWC 011820
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
1120 AM MST TUE SEP 1 2026
SYNOPSIS
STORM CHANCES AND COVERAGE DECREASE TODAY AND WEDNESDAY, THEN
INCREASE AGAIN THURSDAY INTO THE WEEKEND. HIGH TEMPERATURE WILL
BE BELOW NORMAL DURING THE WORK WEEK THEN NEAR NORMAL THIS
WEEKEND.
DISCUSSION
THIS DISCUSSION WILL COVER THE MID MORNING UPDATE AND THE REST
OF THE AFTERNOON.
ISO TO PERHAPS SCT SHOWERS/STORMS TODAY, MAINLY SOUTH OF TUCSON
AND ALONG THE INTERNATIONAL BORDER. MAIN THREATS WITH TODAY'S
ACTIVITY WOULD BE GUSTY WINDS IN EXCESS OF 35 MPH, BRIEF HEAVY
RAIN, AND LIGHTNING. ANY ACTIVITY WILL QUICKLY WANE AFTER SUNSET
AS WE STABILIZE.
MORE ACTIVITY IS EXPECTED WEDNESDAY AS CAMS SHOW MORE SCT
COVERAGE ACROSS THE AREA. COVERAGE AREAS GENERALLY FROM TUCSON
METRO SOUTH AND EAST. MAIN THREATS WILL CONTINUE TO BE GUSTY
WINDS (WHICH COULD BE STRONGER IN EXCESS OF 40 MPH) AND HEAVY
RAIN. WITH THE STORMS A LITTLE MORE ORGANIZED ON WED, THERE IS
MORE OF A THREAT OF LOCALIZED FLASH FLOODING. 12Z HREF GIVES A
10% PROB OF 3" TOTALS IN SANTA CRUZ COUNTY.
LATE IN THE WEEK AND INTO THE WEEKEND THE TROPICS WILL BEGIN TO
COME INTO PLAY ALONG WITH A DEEPENING TROUGH OVER THE PACIFIC
NORTHWEST. TROPICAL STORM MARIE, CURRENTLY CENTERED WELL SOUTH
OF BAJA, WILL BE MOVING NORTHWESTWARD OVER THE NEXT FEW DAYS.
THE NHC TRACK KEEPS IT WELL WEST OF BAJA AS IT TRAVELS
NORTHWARD, BUT THERE IS SOME UNCERTAINTY IN THE TRACK AFTER
FRIDAY. SOME MODELS FAVOR A MORE NORTHWARD TRACK RATHER THEN
NORTHWESTWARD. THIS WILL DEPEND ON HOW FAR SOUTH THE
AFOREMENTIONED UPPER LEVEL LOW TRAVELS. HOWEVER EVEN WITH THE
UNCERTAINTY IN THE TRACK ENSEMBLES ARE IN FAIRLY GOOD AGREEMENT
WITH AN INCREASE IN MOISTURE FROM THE TROPICS BEGINNING AS EARLY
AS THURSDAY. EXPECT MONSOON THUNDERSTORM ACTIVITY TO RAMP BACK
UP STARTING THURSDAY INTO THE WEEKEND. BY FRIDAY MEAN PWAT
VALUES ARE 1.5"-1.8" FROM TUCSON WESTWARD. PWAT VALUES NEAR 2"
IN FAR WESTERN PIMA COUNTY ARE NOT OUT OF THE QUESTION. THIS
INCREASE IN MOISTURE WILL LEAD TO A RISK FOR HEAVY RAINFALL AND
FLASH FLOODING. WPC HAS SOUTHEAST ARIZONA UNDER A SLIGHT RISK
FOR EXCESSIVE RAINFALL THURSDAY AND FRIDAY.
HIGH TEMPERATURES WILL REMAIN A FEW DEGREES BELOW NORMAL THROUGH
THE REST OF THE WORK WEEK THEN WARM A FEW DEGREES TO AROUND
NORMAL THIS WEEKEND.
AVIATION /18Z TUESDAY THROUGH 18Z WEDNESDAY/
FEW/SCT MID LEVEL CLOUDS ACROSS COCHISE AND SOUTHERN GRAHAM
COUNTY THIS MORNING. EXPECT FEW/SCT, POTENTIALLY BKN DECKS 8-12K
FT AGL THIS AFTERNOON DUE TO CUMULUS BUILDUPS AND ISO/SCT
SHOWERS AND STORMS. MOST LIKELY AREA FOR ANY ACTIVITY WILL BE
ALONG AND JUST NORTH OF THE INTERNATIONAL BORDER. GUSTY WINDS
TO 30 KTS WILL BE POSSIBLE NEAR TSRA. OTHERWISE WINDS WILL BE
WEST NORTHWEST 5-10 KTS THIS AFTERNOON AND EVENING, AND LIGHT
AND TERRAIN DRIVEN AT OTHER TIMES. AVIATION DISCUSSION NOT
UPDATED FOR TAF AMENDMENTS.
FIRE WEATHER
EXPECT ISOLATED STORMS TODAY AND WEDNESDAY WITH ACTIVITY MAINLY
FROM TUCSON SOUTH AND EASTWARD. THEN EXPECT AN INCREASE IN
STORM CHANCES THURSDAY INTO THE WEEKEND AS TROPICAL MOISTURE
MOVES IN. TEMPERATURES WILL BE AROUND NORMAL TODAY THROUGH THE
COMING WORK 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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