356
FXUS63 KARX 231955
AFDARX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
255 PM CDT TUE JUN 23 2026
KEY MESSAGES
- WIDESPREAD THUNDERSTORMS LIKELY THIS EVENING (75% TO 95% CHANCE),
WITH MODERATE RAINFALL RATES, AND NEAR-ZERO SEVERE WEATHER POTENTIAL.
- THUNDERSTORMS LIKELY (50% TO 80% CHANCE) TOMORROW LATE
AFTERNOON/EVENING IN SOUTHWESTERN WISCONSIN.
- PROBABILITY INCREASING OF MAJOR HEAT IMPACTS (20% TO 40% CHANCE)
STARTING ON SUNDAY AND LASTING INTO NEXT WEEK.
DISCUSSION
ISSUED AT 255 PM CDT TUE JUN 23 2026
THIS AFTERNOON AND TONIGHT
AT 2 PM THIS AFTERNOON, THERE WERE THUNDERSTORMS OVER WEST-CENTRAL
TO CENTRAL MINNESOTA. THESE STORMS WERE NOT SEVERE, AND PRODUCED
RAINFALL RATES OF AROUND 0.25 TO 0.5 INCHES PER HOUR. THESE STORMS
WERE ASSOCIATED WITH THE LEADING EDGE OF A SOMEWHAT VERTICALLY
STACKED AREA OF LOW PRESSURE THAT IS SLOWLY PROPAGATING EASTWARD
ALONG THE CANADA/US BORDER OVER NORTH DAKOTA.
TIMING-WISE, THESE STORMS ARE SLATED TO REACH THE ARX CWA TOWARDS
THE END OF PEAK HEATING FROM 6PM - 8PM. WITH INSTABILITY WANING,
MUCAPE VALUES WILL STRUGGLE TO REACH 500 J/KG, AND 0-6KM SHEAR
VALUES STRUGGLE TO REACH 30 KTS. IN ALL, THERE ARE NOT THE
PARAMETERS PRESENT TO SUPPORT SEVERE WEATHER DEVELOPMENT, AND THE
SEVERE WEATHER POTENTIAL IS NEAR-ZERO. SEVERAL ROUNDS OF STORMS ARE
LIKELY TO LAST INTO THE OVERNIGHT HOURS, WITH RAINFALL RATES WANING
TOWARDS SUNRISE.
RAINFALL RATE-WISE, THERE ARE ACTUALLY SOME PARAMETERS THAT SUGGEST
MODERATE RAINFALL RATES ARE POSSIBLE WITH THESE STORMS. MORE
SPECIFICALLY, THERE IS AROUND A 60% CHANCE OF RAINFALL RATES
REACHING 1 INCH PER HOUR. THUS, HAVE TRENDED TOTAL EXPECTED
RAINFALL UPWARDS TO CLOSER TO THE 0.75 TO 1 INCH RANGE. THE LARGE
SLUG OF MOISTURE/SATURATION WITHIN THE 0-6KM LAYER MOVES EAST OF THE
ARX CWA BY 12Z WED, ENDING THE MOST INTENSE RAINFALL. GIVEN THE
ANTECEDENT DRY CONDITIONS AND TIME OF YEAR, NO FLOODING IS EXPECTED
AT THIS TIME.
WEDNESDAY
THE CORE OF THE AFOREMENTIONED LOW PRESSURE PIVOTS AND MEANDERS
ALONG LAKE SUPERIOR WEDNESDAY INTO WEDNESDAY NIGHT, KEEPING
THUNDERSTORMS IN THE FORECAST FOR WEDNESDAY AFTERNOON/EVENING. AT
THIS TIME, THERE IS A 'MARGINAL' RISK FOR SEVERE WEATHER FOR THE
EASTERN TIER OUR WISCONSIN COUNTIES (CLARK, TAYLOR, SOUTHWARD
THROUGH GRANT COUNTY)- THAT FEATURES A 5% CHANCE OF LARGE HAIL, 5%
CHANCE OF DAMAGING WINDS, AND A 2% CHANCE OF A TORNADO WITHIN 25
MILES OF A GIVEN POINT. SPORADIC CLEARING MAY AID INSTABILITY AND
SUPPORT MUCAPE VALUES NEARING 1000 J/KG. A WEAK COLD FRONT PASSING
THROUGH WEDNESDAY EVENING WITH THE ACCOMPANYING LOW MAY BE ENOUGH TO
GET STORMS ROOTED A LITTLE CLOSER TO THE SURFACE AND LESS PURELY
ELEVATED IN NATURE... HENCE THE 'MARGINAL' SEVERE RISK. WILL MONITOR
OVERNIGHT TRENDS.
THE OVERALL HEAVY RAINFALL PARAMETER SPACE IS NOT PRESENT. SO AM
STRUGGLING TO SEE MEAN PRECIP VALUES BEING MUCH ABOVE THE 0.1 INCH
TO 0.2 INCH RANGE FOR WEDNESDAY EVENING.
THURSDAY THROUGH SATURDAY
ZONAL FLOW WILL BE FOUND ACROSS MUCH OF THE NORTHERN US. DEPENDING
ON THE TIMING OF SHORTWAVE TROUGHS, THERE ARE SMALL CHANCES (10% TO
15% CHANCE) OF SHOWERS AND STORMS. HIGH TEMPERATURES WILL BE IN THE
MID TO UPPER 70S, TO THE LOW 80S ON SATURDAY.
SUNDAY THROUGH MONDAY
PROBABILITY INCREASING OF MAJOR HEAT IMPACTS (20% TO 40% CHANCE)
STARTING ON SUNDAY AND LASTING INTO NEXT WEEK. AS A LONGWAVE TROUGH
IN THE WESTERN US AMPLIFIES, AN UPPER LEVEL RIDGE WILL BUILD ACROSS
THE UPPER MISSISSIPPI RIVER VALLEY FROM SATURDAY THROUGH MONDAY.
THIS PATTERN WILL BE PERSISTENT THROUGH MUCH OF NEXT WEEK, MAKING
ABOVE-AVERAGE TEMPERATURES LIKELY (80%+ CHANCE) INTO THE JULY 4TH
WEEKEND. BY THE MIDDLE OF NEXT WEEK, THERE IS A 60% TO 80% CHANCE OF
'MODERATE' HEAT RISK IMPACTS- IMPACTS THAT WILL AFFECT THOSE WHO ARE
SENSITIVE TO HEAT, ESPECIALLY THOSE WITHOUT COOLING/HYDRATION.
DEPENDING ON THE POSITION OF THIS RIDGE, THERE MAY BE PERIODS OF
STORMS THROUGHOUT THE WEEK (20% TO 50% CHANCE).
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1255 PM CDT TUE JUN 23 2026
MAIN AVIATION IMPACT IS INCREASING STORM CHANCES FROM WEST TO
EAST INITIALLY LATER THIS AFTERNOON AND INTO THE EARLY EVENING,
GRADUALLY BECOMING MORE WIDESPREAD OVERNIGHT.
PERIODS OF TSRA/VCTS LIKELY THROUGH AROUND 09Z WED OR SO, ALONG
WITH MVFR CEILINGS. PROB30 IFR AT KRST FROM 01Z WED THROUGH 05Z
WED. TIMING AND FORECAST CONFIDENCE WILL LIKELY NEED TO BE
TWEAKED AS WE HEAD INTO THE LATER AFTERNOON HOURS.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
ARX WATCHES/WARNINGS/ADVISORIES
WI...NONE.
MN...NONE.
IA...NONE.
DISCUSSION...KOTENBERG
AVIATION...KOTENBERG
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