014
FXUS65 KTWC 010920
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
220 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
THE UPPER AIR PATTERN REMAINS IN A TRANSITIONAL
PHASE THIS WEEK WITH HIGH PRESSURE CENTERED OVER THE SOUTHEAST
U.S. AND TROUGHING OVER THE WEST COAST. AFTER AN ACTIVE WEEKEND
AND BEGINNING OF THE WEEK MONSOON ACTIVITY WILL DECREASE OVER
THE NEXT COUPLE OF DAYS. SOUTHWESTERLY FLOW IN THE MID-LEVELS
WILL REDUCE MOISTURE SLIGHTLY TODAY AND WEDNESDAY. ENOUGH
MOISTURE WILL STILL BE IN PLACE FOR ISOLATED THUNDERSTORMS SOUTH
AND EAST OF TUCSON EACH AFTERNOON AND EVENING. CAMS SHOW
WEDNESDAY AS BEING THE SLIGHTLY MORE ACTIVE DAY WITH STORMS
CAPABLE OF GUSTY OUTFLOW WINDS AND BRIEF HEAVY RAINFALL MAINLY
ALONG THE INTERNATIONAL BORDER.
LATE IN THE WEEK INTO THE WEEKEND THE TROPICS WILL BEGIN TO COME
INTO PLAY ALONG WITH A DEEPENING TROUGH OVER THE PACIFIC
NORTHWEST. JUST NAMED 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 ALREADY 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
VALID THROUGH 02/12Z.
MOSTLY CLEAR SKIES THIS MORNING WITH SOME MID-LEVEL CLOUDS ALONG
THE AZ/NM BORDER. ISOLATED STORMS FROM KTUS SOUTH AND EASTWARD
WILL BE POSSIBLE STARTING AROUND 01/20Z THROUGH 02/03Z. SKIES
WILL BE SCT-BKN 8K-12K FT AGL THIS AFTERNOON INTO THE EVENING.
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 TUESDAY 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.
HARDIN
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