319
FXUS65 KTWC 020918
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
218 AM MST WED SEP 2 2026
SYNOPSIS
LITTLE MORE STORM ACTIVITY TODAY COMPARED TO
YESTERDAY, ESPECIALLY SOUTH OF TUCSON. THURSDAY INTO THE
WEEKEND TROPICAL MOISTURE MOVES IN LEADING TO A FURTHER INCREASE
IN STORM COVERAGE AND CHANCES WITH THE MAIN THREAT BEING HEAVY
RAINFALL. HIGH TEMPERATURE WILL WILL FLUCTUATE BETWEEN NORMAL
AND A FEW DEGREES BELOW NORMAL.
DISCUSSION
SKIES ARE CLEARING ACROSS THE CWA WITH JUST SOME
MID-LEVEL CLOUD COVER EAST OF TUCSON. ALOFT WE ARE IN A
TRANSITIONAL MONSOON PATTERN WITH THE RIDGE WELL TO THE EAST AND
A CLOSED LOW OVER THE PACIFIC NORTHWEST. THERE HAS BEEN SOME
REDUCTION IN MOISTURE OVER THE PAST DAY, BUT PWATS ARE STILL
AROUND NORMAL. CAMS SHOW A LITTLE MORE THUNDERSTORM ACTIVITY
TODAY COMPARED TO TUESDAY WITH STORM CHANCES EXTENDING NORTH
INTO TUCSON AND SOUTHERN PINAL COUNTY. BUT GREATEST COVERAGE
AND CHANCES WILL STILL BE SOUTH OF TUCSON. THE 02/00Z HREF SHOWS
A 20-50 PERCENT CHANCE FOR 1"-1.5" HOURLY RAINFALL RATES FROM
SELLS TO SIERRA VISTA THIS AFTERNOON AND EVENING. THIS COULD
LEAD TO ISOLATED AREAS OF FLASH FLOODING WITH A SECONDARY THREAT
OF STRONG GUSTY WINDS TO 45 MPH. INITIAL STORMS COULD FORM AS
EARLY AS NOON THEN CONTINUE AN HOUR OR TWO AFTER SUNSET WITH
GENERAL MOTION TO THE NORTH NORTHEAST.
DOWN IN THE TROPICS, TROPICAL STORM MARIE IS CENTERED ABOUT 450
MILES SOUTH OF THE SOUTHERN TIP OF BAJA MOVING NORTHWESTWARD. IT
IS FORECASTED TO BECOME A HURRICANE LATER THIS MORNING. AS IT
CONTINUES ITS NORTHWESTWARD TRACK TROPICAL MOISTURE WILL BEGIN
TO BE ADVECTED NORTHWARD THURSDAY INTO THE WEEKEND. PWATS WILL
LIKELY RANGE FROM 1.4" NEAR THE AZ/NM BORDER TO 1.8" IN WESTERN
PIMA COUNTY. FOR THURSDAY THIS MEANS EXPANDED STORM COVERAGE
NORTHWARD WITH SCATTERED CONVECTION OVER MOST OF THE CWA FROM
CENTRAL PIMA COUNTY EASTWARD. ACCORDING TO THE HREF THE HEAVIEST
RAINFALL THREAT WILL BE FROM TUCSON SOUTHWARD. THE MAIN THREAT
AGAIN WILL BE HEAVY RAINFALL LEADING TO FLASH FLOODING.
THE TROPICAL MOISTURE STICKS AROUND THROUGH AT LEAST THE
FIRST PART OF NEXT WEEK, WHICH WILL LEAD TO DAILY AFTERNOON AND
EVENING THUNDERSTORMS CAPABLE OF HEAVY RAINFALL. EXPECT AREA
WASHES AND RIVERS TO BE RUNNING BY FRIDAY INTO THE WEEKEND,
ESPECIALLY SOUTH OF TUCSON WHERE SOILS ARE ALREADY FAIRLY
SATURATED. ALOFT THE CLOSED LOW REMAINS OVER THE PACIFIC
NORTHWEST THROUGH MONDAY, THEN BEGINS TO MOVE INLAND THEREAFTER.
HOWEVER ENSEMBLES BRING ANOTHER TROUGH IN RIGHT BEHIND, SO
EXPECT ARIZONA TO STAY IN A TRANSITIONAL MONSOON PATTERN INTO
NEXT WEEK.
OVER THE NEXT WEEK HIGH TEMPERATURES WILL FLUCTUATE BETWEEN
NORMAL AND A FEW DEGREES BELOW NORMAL.
AVIATION
VALID THROUGH 03/12Z.
EXPECT SCT-BKN CLOUDS 8-12K FT AGL LATE THIS MORNING INTO THE
EVENING. TSRA COVERAGE WILL LIKELY INCREASE COMPARED TO
YESTERDAY WITH ISOLATED TO SCATTERED TSRA FROM TUCSON SOUTH AND
EASTWARD STARTING AS EARLY AS 02/20Z AND CONTINUING THROUGH
03/04Z. KOLS WILL HAVE THE BEST CHANCES TO BE IMPACTED BY A
STORM. NEAR THUNDERSTORMS EXPECT HEAVY RAINFALL AND GUSTY WINDS
TO 35 KTS. 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 TO SCATTERED STORMS TODAY
MAINLY FROM TUCSON SOUTH AND EASTWARD. STORM CHANCES AND
COVERAGE THEN INCREASE THURSDAY INTO THE WEEKEND AS TROPICAL
MOISTURE MOVES IN. HEAVY RAINFALL LEADING TO FLASH FLOODING WILL
BE THE MAIN THREAT. TEMPERATURES WILL BE AROUND NORMAL TO A FEW
DEGREES BELOW NORMAL TODAY 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.
HARDIN
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