676
FXUS65 KTWC 212036
AFDTWC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
136 PM MST MON SEP 21 2026
SYNOPSIS
A MODEST INCREASE IN MOISTURE WILL BRING PARTLY
CLOUDY SKIES WITH A SLIGHT CHANCE OF A SHOWER THIS AFTERNOON
AND EARLY THIS EVENING. MOISTURE WILL CONTINUE TO INCREASE AFTER
TODAY BRINGING DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS
THROUGH MUCH OF THE WEEK.
DISCUSSION
AN UPPER LOW OVER CENTRAL-SOUTHERN CALIFORNIA WILL CONTINUE TO
BRING SOUTHWESTERLY FLOW ACROSS THE REGION. TUCSON'S PWATS ARE
CURRENTLY 0.89 INCHES FROM GOES AND MOISTURE CONTENT WILL
INCREASE THROUGH THE REST OF THE DAY. MAJORITY OF THE MOISTURE
WILL BE IN THE FORM OF CLOUD BUT THERE ARE SLIGHT CHANCES FOR
SHOWER AND THUNDERSTORMS FROM TUCSON AND EAST.
THE UPPER LEVEL LOW OVER CENTRAL-SOUTHERN CALIFORNIA WILL
CONTINUE TO BRING MOISTURE FOR THE NEXT 3 DAYS. THE BULK OF THE
MOISTURE WILL BE SITTING TO OUR EAST AND TUCSON WILL BE ON THE
OUTER EDGE OF ABOVE NORMAL MOISTURE. THERE WILL BE DAILY CHANCES
FOR RAIN SHOWERS AND THUNDERSTORMS THROUGH THURSDAY. LATEST CAM
GUIDANCE HAS SHOWERS STARTING LATE TONIGHT AND INCREASING
COVERAGE BY TOMORROW AFTERNOON. THERE ARE 10% FROM SELLS TO 50%
BY THE NEW MEXICO STATE LINE FOR A QUARTER OF INCH OF RAIN IN A
6 HOUR PERIOD. CHANCES FOR HALF INCH ARE 10-40% IN A 6 HOUR
PERIOD WILL BE ALONG THE STATE LINE. RAIN AND THUNDERSTORM
CHANCES WILL CONTINUE THROUGH THURSDAY.
BY FRIDAY, UPPER LEVEL MOISTURE WILL DECREASE AND AS RESULT,
LOWER CHANCES FOR RAIN SHOWERS AND THUNDERSTORMS. DAILY CHANCES
WILL RETURN BY SUNDAY, BUT THERE ARE STILL DISAGREEMENT ON HOW
THE ENSEMBLES TRY TO RESOLVE THE INFLUENCE OF TROPICAL STORM
POLO. FOR NOW, RAIN AND THUNDERSTORM CHANCES WILL BE 25-30% FOR
THE START OF THE NEW WEEK.
AVIATION
VALID THROUGH 23/00Z.
SCT-BKN HIGH CLOUDS AT 20-25K FT AGL THROUGH THE FORECAST
PERIOD. SCT-BKN 8K-11K FT CEILINGS DEVELOPING THROUGH THE REST
OF THE AFTERNOON AND INTO TOMORROW. A 10-15 PERCENT CHANCE OF A
-SHRA/-TSRA THIS AFTERNOON FROM KTUS AND EAST. CHANCES INCREASE
THROUGH THE NIGHT FOR SHRA THROUGH THE NIGHT FOLLOWED BY -TSRA
CHANCES BY TOMORROW MID-MORNING TO EARLY AFTERNOON. SURFACE
WINDS WILL BE LESS THAN 12 KTS THROUGH THE FORECAST PERIOD.
AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
FIRE WEATHER
MINIMUM RELATIVE HUMIDITY 20-30 PERCENT IN THE
LOWER ELEVATIONS AND 30-40 PERCENT IN THE MOUNTAINS TODAY,
INCREASING FURTHER FOR THE REMAINDER OF THE WEEK ESPECIALLY
ACROSS GRAHAM, GREENLEE, AND COCHISE COUNTIES. CHANCES FOR
SHOWERS AND THUNDERSTORMS WILL ALSO ARRIVE DAILY TUESDAY ONWARDS
WITH THIS MOISTURE INCREASE. GUSTY AND ERRATIC WINDS WILL
ACCOMPANY ANY THUNDERSTORMS.
TWC WATCHES/WARNINGS/ADVISORIES
NONE.
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