646
FXUS63 KARX 211723
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1223 PM CDT FRI AUG 21 2026
KEY MESSAGES
- SCATTERED STORMS POSSIBLE IN SOUTHWEST WISCONSIN EARLY THIS
AFTERNOON, SOME OF WHICH MAY BE ON THE STRONGER SIDE.
- SEASONAL TEMPERATURES CONTINUE INTO NEXT WEEK WITH HIGHS IN
THE 70S TO LOWER 80S.
- DRY WEEKEND WITH THE NEXT POTENTIAL ROUND OF STORMS COMING
TUESDAY AND WEDNESDAY OF NEXT WEEK.
DISCUSSION
ISSUED AT 1220 PM CDT FRI AUG 21 2026
EARLY THIS AFTERNOON: STORM POTENTIAL
AS OF MIDDAY, OUR WEAK COLD FRONT STRETCHES ALONG A LINE FROM
NEAR OELWIEN, IA TO EAST OF EAU CLAIRE, WI. FORECAST PROFILES
IN THE PREFRONTAL AIRMASS SHOW AMPLE INSTABILITY ON THE ORDER OF
2000-2500 J/KG OF MLCAPE, BUT THE WIND PROFILES--WHILE LINEAR
TO THE SOUTHEAST--WILL INITIALLY STRUGGLE TO SUPPORT ORGANIZED
CONVECTION GIVEN THAT THE STRONGER MID TO UPPER LEVEL FLOW LOOKS
TO NOT ARRIVE UNTIL 21-00Z. BY THE TIME THE STRONGER FLOW
ARRIVES AND THE HODOGRAPHS ELONGATE, THE FRONT WILL HAVE
PROGRESSED OUT OF THE FORECAST AREA AND TAKEN THE SEVERE WEATHER
THREAT WITH IT. THEREFORE, WHILE ONE CANNOT RULE OUT A PULSE
STORM CAPABLE OF PRODUCING LOWER END SEVERE HAIL IN SOUTHWESTERN
WISCONSIN BETWEEN 18-21Z, THE MAIN SEVERE WEATHER THREAT WINDOW
FOR THE DAY CONTINUES TO LOOK TO BE JUST TO THE SOUTH AND EAST
OF THE FORECAST AREA.
IT IS ALSO WORTH NOTING THE 175-200 J/KG OF 0-3-KM CAPE
AVAILABLE IN SOUTHWESTERN WISCONSIN AHEAD OF THE FRONT. IF A
LOCAL SURFACE VORTICITY MAX WERE TO CO-LOCATE UNDER AN UPDRAFT
FOR A PROLONGED PERIOD OF TIME, WE COULD SEE LANDSPOUT PROCESSES
IN PLAY.
SATURDAY - MIDWEEK: DRY EARLY, STORMS RETURN TUESDAY
NORTHWEST FLOW RETURNS TO THE REGION FOR THE WEEKEND AS A
TROUGH AMPLIFIES TO OUR EAST AND THE RIDGE SETS UP TO OUR WEST.
THIS RIDGE DECAYS AS IT MOVES EASTWARD INTO EARLY NEXT WEEK.
WITH OUR REGION IN BETWEEN THESE TWO FEATURES AND UNDER THE
INFLUENCE OF SURFACE HIGH PRESSURE, WE LOOK TO BE MOSTLY DRY
AND SLIGHTLY COOLER THROUGH THE WEEKEND UNTIL THE RIDGE BREAKS
DOWN ON TUESDAY. HIGH TEMPERATURES STAY IN THE LOW 70S TO LOW
80S FROM SATURDAY THROUGH MONDAY.
IT WILL NOT BE UNTIL TUESDAY AS A SHORTWAVE CRESTS THE
FLATTENING RIDGE THAT THE NEXT RISK FOR STORMS ARRIVES WITH THE
MEDIUM RANGE ENSEMBLES IN GOOD AGREEMENT (60-80%) THAT THERE
WILL BE STORMS DURING THIS PERIOD. THE EXACT TIMING AND
PLACEMENT DETAILS OF THIS RAIN WILL BE HAMMERED OUT AS WE GET
CLOSER TO THE EVENT. BEYOND TUESDAY, THE FORECAST IS LOOKING
RELATIVELY DRY FOR THE MIDDLE TO LATTER PART OF NEXT WEEK AS THE
UPPER LEVEL RIDGE REBUILDS TO OUR WEST.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1220 PM CDT FRI AUG 21 2026
MAINLY VFR CONDITIONS ARE FORECAST FOR THE TAF PERIOD WITH
SCATTERED THUNDERSTORMS OVER SOUTHWESTERN WI BEFORE 21Z THIS
AFTERNOON THAT COULD BRING BRIEF RESTRICTIONS. VALLEY FOG MAY
DEVELOP OVER THE WISCONSIN RIVER VALLEY OVERNIGHT AND DISSIPATE
AFTER SUNRISE SATURDAY. WINDS VEER TO THE NORTHWEST BEHIND A
PASSING COLD FRONT THIS AFTERNOON AT 10-15 KTS, BECOMING 5-10
KTS OVERNIGHT AND THEN INCREASING AGAIN TO 10-15 KTS FOR THE DAY
ON SATURDAY. NO ADDITIONAL RAINFALL IS EXPECTED THROUGH THE
WEEKEND, THROUGH OVERNIGHT/MORNING VALLEY FOG MAY IMPACT SOME
SITES INTO EARLY NEXT WEEK.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...SKOW
AVIATION...SKOW
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