052
FXUS63 KARX 172343
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
643 PM CDT MON AUG 17 2026
KEY MESSAGES
- A FEW ROUNDS OF SHOWERS AND STORMS ARE POSSIBLE TONIGHT THROUGH
TUESDAY WITH A VERY LOW CHANCE FOR DAMAGING WIND GUSTS.
- THERE ARE CHANCES FOR PERIODIC SHOWERS AND STORMS FROM THURSDAY
NIGHT THROUGH SATURDAY
- NEAR NORMAL TEMPERATURES ARE FORECAST OVER THE NEXT WEEK WITH
AFTERNOON HIGHS IN THE 70S TO LOW 80S.
DISCUSSION
ISSUED AT 106 PM CDT MON AUG 17 2026
REST OF TODAY INTO TUESDAY: A FEW ROUNDS OF SHOWERS AND STORMS
MILD CONDITIONS ARE FORECAST FOR THE REST OF THE AFTERNOON WITH
PARTLY CLOUDY SKIES AND TEMPERATURES RISING INTO THE UPPER 70S TO
LOW 80S ACROSS THE REGION. SHORTWAVES EMBEDDED IN THE WESTERLY FLOW
ALOFT WILL LIKELY MOVE OVER THE UPPER MIDWEST LATER THIS AFTERNOON
INTO TONIGHT. INITIAL DEVELOPMENT OF SHOWERS AND THUNDERSTORMS IS
FORECAST TO BEGIN IN THE DAKOTAS TO NORTHERN/WESTERN MINNESOTA THIS
AFTERNOON. THIS ACTIVITY SHOULD MOVE TOWARDS THE EAST/SOUTHEAST
AS THE UPPER LEVEL WAVE MOVES TOWARDS THE GREAT LAKES REGION.
JUST HOW FAR EAST/SOUTHEAST THE LINEAR COMPLEX OF SHOWERS AND
STORMS GETS VARIES IN THE DETERMINISTIC AND ENSEMBLE GUIDANCE.
UNFORTUNATELY, THE POTENTIAL IS CERTAINLY THERE THAT MOST OF THE
CONVECTION DISSIPATES BEFORE REACHING THE DRIFTLESS REGION, BUT
CURRENT THINKING IS THAT THE LIFT PROVIDED BY THE WAVES AND THE
SUFFICIENT MID LEVEL MOISTURE WILL BE ENOUGH TO BRING
CONVECTION TO AT LEAST THE NORTHWESTERN HALF OF THE AREA
TONIGHT. SEVERE STORMS ARE NOT EXPECTED SINCE THE LINE OF STORMS
WOULD BE MOVING IN WELL AFTER SUNSET THIS EVENING AND CAPE
VALUES ARE MOSTLY BELOW 1000 J/KG BY THE TIME ANY CONVECTION
REACHES THIS FAR EAST.
THE SHOWERS AND, MORE NOTABLY, THE SEVERE STORM POTENTIAL LATER IN
THE DAY ON TUESDAY WILL BE HIGHLY CONTINGENT ON HOW THE FIRST ROUND
OF POTENTIAL SHOWERS/STORMS PANS OUT. IF A POTENTIAL LINE OF STORMS
MOVES THROUGH TOMORROW MORNING, RAIN-COOLED AIR WILL LIKELY REMAIN
IN ITS WAKE LEADING TO A LESSER THREAT FOR SEVERE STORMS WITH THE
SECONDARY WAVE THAT SHOULD MOVE OVER THE AREA LATER IN THE MORNING
THROUGH THE AFTERNOON. EVEN IF EVERYTHING WERE TO ALIGN FOR SEVERE
STORMS DURING THE DAY TOMORROW, THE MAIN HAZARD WOULD BE DAMAGING
WIND GUSTS AS ANOTHER LINEAR SYSTEM PROPELS EAST OVER THE UPPER
MISSISSIPPI RIVER VALLEY. IF ANY STORMS CAN REMAIN DISCRETE, A
THREAT FOR LARGE HAIL MAY ARISE, BUT CONFIDENCE IN VERY LOW IN THAT
POTENTIAL. THE MORE LIKELY SCENARIO IS THAT SHOWERS AND STORMS
REMAIN BELOW SEVERE LEVELS DURING THE DAY ON TUESDAY WITH THE MAIN
HAZARD BEING LIGHTNING. MOST OF THE CONVECTIVE ACTIVITY SHOULD BE
OFF TO THE EAST OF THE AREA BY MID AFTERNOON, BUT THERE COULD BE A
FEW ISOLATED SHOWERS OR STORMS THAT MOVE INTO THE WESTERN ZONES ONCE
AGAIN DURING THE AFTERNOON.
WEDNESDAY THROUGH SATURDAY: PERIODIC RAIN CHANCES
THE REGION SHOULD BE UNDERNEATH THE BASE OF AN H500 TROUGH ON
WEDNESDAY WHICH SHOULD KEEP THE WEATHER QUIET AS LIFT PROVIDED BY
THE TROUGH SHOULD STAY JUST TO THE SOUTHWEST OF THE CWA. ACTIVE
WEATHER MAY QUICKLY RETURN BY THURSDAY AFTERNOON HOWEVER AS RIDGING
BUILDS NORTHWARD OVER THE WESTERN CONUS INTO BRITISH COLUMBIA AND
ALBERTA LATE THIS WEEK INTO THE WEEKEND. ADDITIONAL WAVES EMBEDDED
IN THE NORTHWEST TO NORTH FLOW SHOULD LEAD TO ADDITIONAL SHOWER AND
STORM CHANCES THROUGH SATURDAY MORNING. WITH THE FORECAST AREA IN
BETWEEN THESE TWO SYSTEMS, RELATIVELY MILD CONDITIONS ARE LIKELY
WITH HIGHS RIGHT AROUND TO A FEW DEGREES BELOW AVERAGE EACH DAY.
SATURDAY NIGHT INTO EARLY NEXT WEEK: DRY AND MILD CONDITIONS
THE UPPER LEVEL PATTERN IN THE FORECAST GUIDANCE DIVERGES BEGINNING
SATURDAY THROUGH THE REMAINDER OF THIS FORECAST PERIOD. ENSEMBLE
GUIDANCE IS IN FAIRLY GOOD AGREEMENT THAT SUNDAY WILL REMAIN ON THE
DRY SIDE BUT THAT MAY ONCE AGAIN LEAD TO AN ACTIVE PATTERN TO BEGIN
THE NEXT WORK WEEK. EVEN IF THE SHOWER AND STORM POTENTIAL INCREASES
ONCE AGAIN NEXT WEEK, TEMPERATURES ARE STILL LOOKING TO BE MILD
WITH A MAJORITY OF GUIDANCE KEEPING HIGHS IN THE LOWER 80S TO
UPPER 70S.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 643 PM CDT MON AUG 17 2026
MAIN FORECAST CONCERN FOR THE 00Z TAF PERIOD REVOLVES AROUND
POTENTIAL SHOWER/STORM CHANCES LATE TONIGHT INTO TUESDAY.
CURRENT UPSTREAM CONVECTION OVER MINNESOTA AND THE DAKOTAS LIES
WITHIN A MORE FAVORABLY UNSTABLE AIRMASS. EXPECTATION IS FOR
WEAK INSTABILITY TO SPILL EASTWARD INTO THE UPPER MISSISSIPPI
VALLEY OVERNIGHT, SUPPORTING A CHANCE (30-40%) OF STORMS AT THE
TAF SITES FROM ABOUT 06Z THROUGH 13Z, WITH A LINGERING SMALL
CHANCE (30%) OF SHOWERS THROUGH MID-AFTERNOON. VISIBILITIES
AND/OR CEILINGS MAY BRIEFLY DROP TO MVFR. HOWEVER, GIVEN
UNCERTAINTIES IN STORM TRACK AND COVERAGE, HAVE CONTINUED WITH
PROB30 MENTION IN THE TAFS AND WILL MONITOR TRENDS FOR LATER
UPDATES.
WINDS WILL BE LIGHT OUT OF THE SW TO S OVERNIGHT, SWINGING
AROUND TO THE W-NW DURING THE DAY TUESDAY.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...MUSCHA
AVIATION...KURZ
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