560
FXUS63 KARX 220002
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
702 PM CDT MON SEP 21 2026
KEY MESSAGES
- PERIODS OF LIGHT RAIN TODAY SOUTHWEST OF I-94, FOCUSED MAINLY
SOUTH OF I-90. OVERALL IMPACTS SHOULD BE LIMITED WITH RAINFALL
AMOUNTS GENERALLY OF 1/2" OR LESS.
- COOL AND DRY FOR MUCH OF THE UPCOMING WEEK WITH NEAR TO
SLIGHTLY BELOW NORMAL TEMPERATURES.
- NEXT CHANCE OF WIDESPREAD RAIN ARRIVES OVER THE WEEKEND, BUT
DETAILS OF RAINFALL AMOUNTS AND PLACEMENT REMAIN SPARSE.
DISCUSSION
ISSUED AT 1200 PM CDT MON SEP 21 2026
TODAY - TONIGHT: PERIODS OF LIGHT RAIN
A STACKED MID TO UPPER TROPOSPHERIC CLOSED LOW MEANDERS ESE
ACROSS NORTHERN IOWA THIS AFTERNOON AND TONIGHT, BRINGING WITH
IT PERIODS OF LIGHT TO MODERATE SHOWERS. WITH THE SHOWERS DRIVEN
MAINLY BY DCVA AHEAD OF THE LOW AND LITTLE IN THE WAY OF DEEPER
MOISTURE AND MESOSCALE ASCENT, RAINFALL RATES WILL BE ON THE
LIGHTER SIDE. AS OF 11 AM, RAINFALL AMOUNTS AROUND THE I-35
CORRIDOR HAD TOPPED OUT AROUND 1/2 OF AN INCH, BUT THIS BAND
WAS STARTING TO THIN AND WEAKEN. WHILE TOTAL RAINFALL AMOUNTS
SOUTH OF I-90 COULD APPROACH SIMILAR VALUES (20-30% CHANCE),
THIS RAIN WILL FALL OVER THE COURSE OF SEVERAL HOURS AND HAVE
LITTLE IMPACT AND ANY ELEVATED RIVER LEVELS. THE RAINFALL AXIS
GRADUALLY SPREADS ESE AHEAD OF THE LOW CENTROID, PERSISTING
THROUGH THE EVENING HOURS BEFORE DEPARTING TO THE SOUTHEAST BY
SUNRISE ON TUESDAY. WITH THE WIDESPREAD CLOUDS AND RAIN TODAY,
HIGHS WILL ONLY TOP OUT IN THE LOW TO MID 60S, A FULL TEN
DEGREED BELOW AVERAGE.
REST OF THE WORK WEEK: COOL AND MOSTLY DRY
THE REGION RESIDES ALONG THE WESTERN PERIPHERY OF A LARGE
SOUTHERN ONTARIO/QUEBEC HIGH PRESSURE CELL THROUGHOUT THE
BALANCE OF THE WORK WEEK, KEEPING A COOL AND DRY EAST/SOUTHEAST
FETCH IN PLACE THAT WILL LIMIT THE INTRUSION OF ANY RAIN INTO
THE REGION. A SUBTLE SHORTWAVE GRAZES THE DAKOTAS ON WEDNESDAY,
WITH CONVECTION LIKELY TO MOVE AT LEAST INTO CENTRAL MINNESOTA
BY THURSDAY MORNING. HOWEVER, HOW THIS RAIN SHIELD EVOLVES
AFTERWARDS IS A SOURCE OF FORECAST UNCERTAINTY. MOST SOLUTIONS
DECAY THIS SYSTEM RELATIVELY QUICKLY BEFORE REACHING THE
MISSISSIPPI RIVER, BUT THERE ARE A FEW OUTLIER SOLUTIONS (10%)
THAT ADVECT THE RAIN FARTHER EAST. HOWEVER, ODDS ARE FAVORING
MORE OF A DRY FORECAST DURING THIS PERIOD.
UPCOMING WEEKEND: NEXT CHANCE OF RAIN
A DEEPER LONGWAVE TROUGH APPROACHES THE REGION FOR THE WEEKEND,
SHUNTING THE RIDGE TO THE EAST AND OPENING THE DOOR FOR THE
RETURN OF RAINFALL. WHILE THE BULK OF THE MEDIUM TO LONGER RANGE
GUIDANCE HAVE THIS WAVE RESOLVED, TIMING AND PLACEMENT OF THIS
TROUGH MAKE IT DIFFICULT TO ASCERTAIN ANY DETAILS ABOUT THIS
RAINFALL. WHAT IS MORE CERTAIN IS THAT GIVEN THE LACK OF DEEPER
MOISTURE AND PROGRESSIVE NATURE OF THE SURFACE FRONT, RAINFALL
AMOUNTS DO NOT LOOK TO BE OVERLY HIGH WITH LREF RAINFALL
PROBABILITIES OF >1/2" BEING AROUND 10-20%.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 649 PM CDT MON SEP 21 2026
LOW PRESSURE CENTER UPSTREAM OF THE FORECAST AREA CAUSING
WIDESPREAD LIGHT RAIN ACROSS THE FORECAST AREA. HIGHER IMPACT
MVFR-IFR CIGS PROGRESSING INTO THE WESTERN HALF OF THE FORECAST
AREA EXPECTED TO AFFECT KRST TAF SITE SHORTLY AFTER TAF
ISSUANCE. IFR VISIBILITIES EXPECTED TO REMAIN UPSTREAM OF KRST
ALTHOUGH LOW CONFIDENCE AND MAY NEED FURTHER UPDATE BEFORE 06Z
TAF ISSUANCE.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...SKOW
AVIATION...JAR
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