057
FXUS63 KARX 170537
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
1237 AM CDT MON AUG 17 2026
KEY MESSAGES
- HIGHLY CONDITIONAL SEVERE WEATHER THREAT LATE TUESDAY
AFTERNOON AND NIGHT. IF IT DOES OCCUR, THE MAIN THREAT WOULD
BE DAMAGING WINDS.
- PERIODIC SHOWERS AND STORMS FROM THURSDAY NIGHT INTO SATURDAY.
- MAINLY DRY FROM SATURDAY NIGHT INTO EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 1237 AM CDT MON AUG 17 2026
THIS AFTERNOON AND TONIGHT
AS A SHORTWAVE TROUGH APPROACHES THE AREA FROM THE NORTHERN PLAINS
THIS AFTERNOON, SCATTERED SHOWERS AND STORMS WILL DEVELOP ACROSS
NORTHERN AND WESTERN MINNESOTA. THIS CONVECTION WILL THEN MOVE
SOUTHEAST INTO THE AREA TONIGHT. WITH THE INSTABILITY DECREASING
THIS EVENING, THIS CONVECTION WILL BE ON A WEAKENING TREND. IN
ADDITION THE 0-3 KM AND 0-6 KM SHEAR WILL BE LESS THAN 20 KNOTS, SO
NOT ANTICIPATING ORGANIZED SEVERE WEATHER.
HIGH TEMPERATURES WILL RANGE FROM THE MID-70S TO MID-80S TODAY. LOW
TEMPERATURES WILL RANGE FROM THE UPPER 50S TO LOWER 60S TONIGHT.
TUESDAY AND TUESDAY NIGHT
THE MODELS ARE IN GENERAL AGREEMENT THAT A MESOSCALE CONVECTIVE
COMPLEX WILL DEVELOP OVER EASTERN SOUTH DAKOTA, NORTHWEST IOWA, AND
SOUTHWEST MINNESOTA DURING THE OVERNIGHT TONIGHT AND THIS SYSTEM
WILL EITHER MOVE EAST OR SOUTHEAST. THIS WILL GREATLY IMPACT HOW
MUCH OF THE AREA IS IMPACTED. IF THE TRACK OF THIS SYSTEM IS MORE TO
OUR SOUTHWEST, WE WILL BE ABLE TO BUILD MORE INSTABILITY PRIOR TO
ANOTHER SHORTWAVE TROUGH ON TUESDAY EVENING. IF THIS SYSTEM TRACKS
MORE EAST, MUCH OF THE AREA WILL SEE RAIN-COOLED AIR IN ITS WAKE AND
IN TURN, THERE WOULD BE LITTLE RECOVERY TIME PRIOR TO THE TUESDAY
NIGHT SHORTWAVE TROUGH. IF THERE IS A CHANCE OF SEVERE WEATHER LATE
TUESDAY AFTERNOON AND TUESDAY NIGHT, THE FORMER SOLUTION WOULD
LIKELY HAVE TO OCCUR. THE MAIN SEVERE WEATHER THREAT UNDER THIS
SCENARIO WOULD BE DAMAGING WINDS.
HIGH TEMPERATURES WILL RANGE FROM THE MID-70S TO MID-80S ON TUESDAY.
LOW TEMPERATURES WILL RANGE FROM THE UPPER 40S TO LOWER 60S ON
TUESDAY NIGHT.
THURSDAY NIGHT INTO SATURDAY
FOR LATE THIS WEEK, THE GLOBAL AND ENSEMBLE MODELS ARE IN GENERAL
AGREEMENT THAT THE WESTERN RIDGE WILL RETROGRADE INTO THE SOUTHWEST
US AND THEN BUILD NORTH INTO THE ROCKIES, PACIFIC NORTHWEST, BRITISH
COLUMBIA, ALBERTA, AND SASKATCHEWAN. AS THIS OCCURS, A SERIES OF
SHORTWAVE TROUGHS WILL CARVE OUT AN EASTERN US LONGWAVE TROUGH.
THESE SYSTEMS WILL PROVIDE A CHANCE OF PERIODIC SHOWERS AND STORMS
FROM THURSDAY NIGHT INTO SATURDAY. WHILE THE 0-1 KM MIXED-LAYER
CAPES CLIMB UP TO 1K J/KG AHEAD OF THESE SHORTWAVE TROUGHS, THE
BETTER 0-3 KM AND 0-6 KM SHEAR REMAIN LESS THAN 20 KNOTS. AS A
RESULT, THE THREAT FOR ORGANIZED SEVERE WEATHER REMAINS ON THE LOW
SIDE.
HIGH TEMPERATURES WILL RANGE FROM THE MID-70S TO LOWER 80S FROM
FRIDAY AND SATURDAY. LOW TEMPERATURES WILL RANGE FROM THE MID-50S TO
LOWER 60S ON THURSDAY NIGHT AND FRIDAY NIGHT.
SATURDAY NIGHT INTO EARLY NEXT WEEK
CANADIAN HIGH PRESSURES WILL BUILD ACROSS THE AREA DURING THE
UPCOMING WEEKEND. IT WILL PROVIDE DRY WEATHER AND SEASONABLE
TEMPERATURES. HIGH TEMPERATURES WILL RANGE FROM THE MID-70S TO LOWER
80S AND LOW TEMPERATURES WILL BE IN THE 50S.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1237 AM CDT MON AUG 17 2026
VFR CONDITIONS ARE EXPECTED THROUGHOUT MUCH OF THE TAF PERIOD
WITH THE ONLY CONCERN BEING THE LOW-END POTENTIAL FOR FOG
FORMATION INTO THE MORNING HOURS. CURRENTLY, CONFIDENCE IN THE
NBH AND HREF IS NOT OVERLY HIGH FOR CATEGORY REDUCING FOG
OVERNIGHT. HOWEVER, GIVEN THE SIGNALS IN SOME DETERMINISTIC
MODELS AND THE LIGHT WINDS/CLEAR SKIES OVERNIGHT, HAVE OPTED TO
MAINTAIN SOME VSBY REDUCTIONS. OTHERWISE, CONDITIONS WILL BE VFR
THROUGH THE PERIOD WITH NORTHWESTERLY WINDS SHIFTING TO
SOUTHWESTERLY THROUGHOUT THE DAY AND REMAINING AROUND 8 KTS OR
LESS.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...BOYNE
AVIATION...NAYLOR
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