051
FXUS63 KARX 091835
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
135 PM CDT WED SEP 9 2026
KEY MESSAGES
- STORM CHANCES (30-60%) RETURN MAINLY FRIDAY NIGHT WITH LOW
POTENTIAL (<10%) FOR SEVERE THUNDERSTORMS UNLESS THE TIMING OF
THESE THUNDERSTORMS SHIFTS INTO THE LATE AFTERNOON HOURS OF
FRIDAY OR SATURDAY.
- WIDESPREAD RAIN IS VERY LIKELY (80-90%) MONDAY. HEAVY RAIN AND
PERHAPS FLOODING MAY OCCUR, PARTICULARLY IF LOCATIONS RECEIVE
APPRECIABLE RAIN EARLY SUNDAY AHEAD OF THE MAIN RAIN EVENT (30%
CHANCE).
DISCUSSION
ISSUED AT 125 PM CDT WED SEP 9 2026
THUNDERSTORM POTENTIAL RETURNS FRIDAY NIGHT
FRIDAY INTO SATURDAY, LONGWAVE UPPER TROUGH WILL ADVANCE OVER CANADA
WITH THIS FEATURE EXTENDING SOUTHWARD OVER THE UPPER MIDWEST. WEAK
SURFACE RIDGE IN THE EASTERN CONUS SHOULD LEAD TO SOUTHERLY MOISTURE
FETCH, SETTING THE STAGE FOR A CHANCE (30-60%) OF SHOWERS AND
THUNDERSTORMS AS THE ASSOCIATED SURFACE FRONT PUSHES SOUTHEAST. WITH
WESTERLY WINDS ALOFT RAMPING UP ON THE EQUATOR-WARD SIDE OF THE
UPPER TROUGH, PLENTY OF SHEAR LOOKS TO BE AVAILABLE FOR ORGANIZED
CONVECTION. HOWEVER, MOST GUIDANCE BRING THE FRONT THROUGH THE CWA
BY MID-MORNING SATURDAY, LEADING TO LITTLE IN THE WAY OF
INSTABILITY. THEREFORE, CURRENT THINKING IS THAT THE POTENTIAL FOR A
SEVERE THUNDERSTORM IS LOW (<10%) AND, IF IT WERE TO OCCUR, WOULD
FAVOR FAR SOUTHWEST WISCONSIN EARLY SATURDAY AFTERNOON BEFORE THE
FRONT FULLY CLEARS THE CWA.
RAINY MONDAY WITH FLOODING POTENTIAL
MOIST ADVECTION RESUMES RATHER QUICKLY FOLLOWING SATURDAY'S FRONTAL
PASSAGE WITH THIS RAMPING UP CONSIDERABLY INTO MONDAY. 09.00Z
NAEFS/ECENS PWAT VALUES INCREASE TO THE 90TH AND 99.5TH PERCENTILE
RESPECTIVELY BEFORE COOLING ALOFT AHEAD OF ANOTHER LONGWAVE TROUGH
AND INCREASING WAA LEAD TO WIDESPREAD RAIN. MODERATE (2"+) AMOUNTS
OF RAINFALL APPEAR TO BE GOOD BET NORTH OF I-90 (55-70%). WHILE THE
OVERALL SYSTEM IS PROGRESSIVE AND THUS FLOOD RISK WOULD BE LIMITED
BY DURATION OF THE EVENT, AT LEAST THE 09.00Z EC DEPICTS RAIN
DEVELOPING ALONG THE WARM FRONT MUCH EARLIER THAN OTHER GUIDANCE.
THIS SEEMS TO BE REFLECTED IN 09.00Z ECENS EFI OUTPUT WHICH SHOWS AN
AREA WHERE MANY MEMBERS ARE TOWARD THE 80TH-90TH PERCENTILE
CLIMATOLOGICALLY FOR QPF, AS EXPECTED GIVEN PLENTY OF FORCING AND
MOISTURE AS DISCUSSED ABOVE, WITH A FEW MORE EXTREME MEMBERS WHICH
WOULD REPRESENT THE POTENTIAL EARLIER START TO RAIN. AT THIS TIME,
THIS OUTPUT IS MAINLY WITHIN WEST CENTRAL WISCONSIN NORTH OF I-90.
IF THIS WERE TO OCCUR, COULD SEE A RISK FOR FLOODING DEVELOP. WILL
NEED TO CONTINUE WATCHING THIS PERIOD CLOSELY OVER THE COMING DAYS.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1215 PM CDT WED SEP 9 2026
VFR CONDITIONS SHOULD (80%) PREVAIL AT RST/LSE THROUGH THE NEXT
24 HOURS BUT THERE IS A SMALL (20%) CHANCE FOR FOG TO SPREAD
NORTHWARD TO THESE TERMINALS AROUND 09-12Z THURSDAY. THIS FOG IS
EXPECTED TO MAINLY AFFECT THE USUAL AREAS AROUND THE WISCONSIN
RIVER VALLEY. AS A FRONT SLIDES SOUTHEAST THIS AFTERNOON, SOME
GUSTS TO 25 KNOTS OUT OF THE WEST NORTHWEST WILL OCCUR UNDER
CLEARING SKIES.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...FERGUSON
AVIATION...FERGUSON
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