Thunderstorms developed along a trough of low pressure over northern Wisconsin and produced large hail and damaging winds as they dropped south toward central Wisconsin on July 20th.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS ARX wrote it up.
Thunderstorms developed along a trough of low pressure over northern Wisconsin and produced large hail and damaging winds as they dropped south toward central Wisconsin on July 20th.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS La Crosse, WI wrote its last area forecast discussion before the first event at Jul 20, 1:20 PM CST, 1 hour 13 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 220 PM CDT TUE JUL 20 2010 .SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT CLEARING SKIES ARE EXPECTED FOR THE OVERNIGHT HOURS AFTER THE LATE AFTERNOON/EARLY EVENING CONVECTION WEARS OFF AND SUBSIDENCE SETTLES IN AFTER A WEAK TROF/WIND SHIFT MOVES THROUGH. A RIDGE OF HIGH PRESSURE OVER THE DAKOTAS WILL TRACK EAST OVERNIGHT WHICH WILL KEEP THE PRESSURE GRADIENT LOOSE ACROSS THE REGION AND ALLOW FOR LIGHT TO CALM WINDS OVERNIGHT. LOW LEVEL WINDS ABOVE THE SURFACE WILL BE SLIGHTLY STRONGER THAN THE PAST FEW NIGHTS. SO...WHILE FOG LOOKS POSSIBLE AGAIN OVERNIGHT...IT LIKELY WILL NOT BE AS WIDESPREAD AS THIS MORNING. ANY SPOTS THAT GET HIT BY A ROGUE STORM THIS AFTERNOON WILL HAVE A HIGHER CHANCE OF FOGGING UP OVERNIGHT AS WELL. SHOULD BE FAIRLY QUIET ON WEDNESDAY WITH THE CORE OF A RIDGE OF HIGH PRESSURE IN PLACE WITH A FAIR WEATHER CUMULUS FIELD LIKELY TO DEVELOP. TEMPERATURES ARE EXPECTED TO BE RIGHT AROUND NORMAL WITH HIGHS IN THE MID 80S. THINGS GET A BIT MORE INTERESTING LATE WEDNESDAY NIGHT INTO THURSDAY MORNING AS A 700MB TROF LIFTS NORTHEAST FROM THE CENTRAL PLAINS TO THE UPPER MIDWEST WHILE A LOW PRESSURE SYSTEM IN THE WESTERN PLAINS STARTS TO TRACK NORTHWARD ALONG WITH A WARM FRONT CURRENTLY STRETCHED ACROSS NORTHEAST KANSAS INTO NORTHERN MISSOURI. ANY MCS ACTIVITY WEDNESDAY NIGHT/THURSDAY MORNING SHOULD BE RELEGATED TO THE SOUTH OF THE FORECAST AREA WITH JUST THE NORTHEAST FRINGE OF THE RAIN SHIELD MAKING IT UP INTO THE REGION BY 12Z THURSDAY. THE LOW LEVEL WIND FIELD IS EXPECTED TO STRENGTHEN OUT OF THE SOUTH WEDNESDAY NIGHT INTO THURSDAY NIGHT WHICH WILL ASSIST WITH ADVECTING MORE MOISTURE UP INTO THE REGION ALONG WITH FORCING THE SURFACE/850MB WARM FRONT NORTH AS WELL. IT DOES NOT APPEAR AS THOUGH THE WARM SECTOR OF THE SURFACE SYSTEM WILL MAKE IT INTO THE REGION DURING THE DAY THURSDAY...BUT SHOULD BE ACROSS AT LEAST THE SOUTHEAST HALF OF THE FORECAST AREA BY EVENING. THIS WILL PROVIDE A FAIRLY UNSTABLE ENVIRONMENT FOR STORMS TO DEVELOP IN DURING THE EVENING AND OVERNIGHT HOURS THURSDAY NIGHT. HEAVY RAINFALL WITH THE THUNDERSTORM CLUSTERS WILL BE POSSIBLE THROUGH THE DAY THURSDAY INTO THE OVERNIGHT PERIOD. .LONG TERM...FRIDAY THROUGH TUESDAY THE EXTENDED PERIOD/S MAIN FEATURE CONTINUES TO BE WITH THE DIGGING MID TO UPPER LEVEL TROF THAT IS EXPECTED TO TRACK ACROSS THE UPPER MISSISSIPPI RIVER VALLEY REGION LATE FRIDAY INTO EARLY SATURDAY. A LOW PRESSURE SYSTEM WILL HAVE MADE IT INTO THE UPPER GREAT LAKES REGION ON FRIDAY WITH A COLD FRONT EXTENDING SOUTHWEST THROUGH THE REGION. AT THIS POINT...IT LOOKS LIKE AN MCS WILL POSSIBLY DEVELOP ACROSS IOWA FRIDAY NIGHT INTO SATURDAY MORNING WITH THE FRONT HAVING MADE IT DOWN INTO THIS REGION. A GOOD CHUNK OF FRIDAY MAY END UP BEING DRY WITH THE COLD FRONT SPLITTING THE FORECAST AREA. AS THE MID TO UPPER LEVEL FLOW GOES MORE NORTHWESTERLY BEHIND THE TROF...HIGH PRESSURE WILL BUILD IN ACROSS THE REGION FOR THE WEEKEND ON INTO EARLY NEXT WEEK...BRINGING WITH IT SEASONABLE TEMPERATURES AND DEW POINTS WITH HIGHS EXPECTED IN THE MID TO UPPER 80S AND DEW POINTS IN THE LOW TO MID 60S. THE NEXT FEATURE OF NOTE THAT THE 20.12Z ECMWF AND GFS SHOW IS A COLD FRONT DROPPING DOWN INTO THE REGION FROM THE NORTH ON TUESDAY WHICH COULD LEAD TO SOME SHOWERS AND THUNDERSTORMS. && .AVIATION...LATE THIS AFTERNOON THROUGH WEDNESDAY A TROUGH WILL PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS AS IT MOVES EAST THROUGH THE REGION LATE THIS AFTERNOON AND EVENING. SINCE IT IS QUESTIONABLE WHETHER THEY WILL MAKE IT INTO TAF SITES...THEY WERE NOT INCLUDED INTO THE 20.18Z FORECAST. IF THEY DID...THEY WOULD BE MAINLY CONFINED TO THE 20.20Z TO 21.02Z TIME PERIOD. HIGH PRESSURE WILL BUILD BACK ACROSS THE REGION TONIGHT. THIS HIGH WILL PRODUCE GENERALLY LIGHT WINDS AND CLEAR SKIES. FOG MAY REDUCE VISIBILITIES TO LESS THAN A MILE IN AREAS WHERE PRECIPITATION OCCURS AND IN THE VALLEY LOCATIONS. DUE TO THIS...BCFG WAS ADDED TO THE KLSE TAF BETWEEN 21.09Z AND AND 21.13Z. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && SHORT/LONG TERM...HALBACH AVIATION...BOYNE
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LA CROSSE WI 1125 AM CDT TUE JUL 20 2010 IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029- 032>034-041>044-053>055-061-211100- ADAMS-ALLAMAKEE-BUFFALO-CHICKASAW-CLARK-CLAYTON-CRAWFORD-DODGE- FAYETTE-FILLMORE-FLOYD-GRANT-HOUSTON-HOWARD-JACKSON-JUNEAU- LA CROSSE-MITCHELL-MONROE-MOWER-OLMSTED-RICHLAND-TAYLOR-TREMPEALEAU- VERNON-WABASHA-WINNESHIEK-WINONA- 1125 AM CDT TUE JUL 20 2010 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF NORTHEAST IOWA... SOUTHEAST MINNESOTA AND SOUTHWEST INTO CENTRAL WISCONSIN. .DAY ONE...THIS AFTERNOON AND TONIGHT A WEAK FRONT WILL PRODUCE SCATTERED THUNDERSTORMS AS IT MOVES THROUGH THE REGION THIS AFTERNOON. A FEW OF THESE THUNDERSTORMS MAY BECOME SEVERE ALONG AND NORTH OF THE INTERSTATE 90 CORRIDOR. IF THIS DOES OCCUR...LARGE HAIL AND DAMAGING WINDS LOOK TO BE THE PRIMARY THREATS. .DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY A LOW PRESSURE SYSTEM WILL STRENGTHEN OVER THE CENTRAL PLAINS WEDNESDAY...THEN LIFT NORTHEAST INTO AND ACROSS THE REGION THURSDAY AND THURSDAY NIGHT. THUNDERSTORM CHANCES WILL INCREASE AND SPREAD INTO THE AREA WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. THERE IS A SLIGHT RISK OF SEVERE STORMS WITH THIS SYSTEM...MAINLY THURSDAY AFTERNOON AND EVENING. LARGE HAIL AND DAMAGING WINDS WOULD BE THE MAIN SEVERE THREATS...ALONG WITH THE POSSIBILITY OF LOCALLY HEAVY RAINS AND ISOLATED TORNADOES. A CHANCE OF THUNDERSTORMS LINGERS ON FRIDAY. THE RISK OF SEVERE WEATHER WITH ANY STORMS ON FRIDAY APPEARS QUITE LOW AT THIS TIME. .SPOTTER INFORMATION STATEMENT... DUE TO THE ISOLATED NATURE OF THIS SEVERE WEATHER THREAT THIS AFTERNOON...WIDESPREAD SPOTTER ACTIVATION IS NOT ANTICIPATED. .EMERGENCY MANAGEMENT COORDINATION... NO CALL IS SCHEDULED. RRS/BOYNE
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE LA CROSSE WI 153 PM CDT TUE JUL 20 2010 WIZ017-029-201945- CLARK-TAYLOR- 153 PM CDT TUE JUL 20 2010 ...SCATTERED THUNDERSTORMS EXPECTED ACROSS CLARK AND TAYLOR COUNTIES THIS AFTERNOON... THROUGH 3 PM...SCATTERED SHOWERS AND THUNDERSTORM WILL CONTINUE TO DEVELOP ACROSS TAYLOR AND CLARK COUNTIES. A FEW OF THESE THUNDERSTORMS MAY PRODUCE WIND GUSTS UP TO 30 MPH AND PEA SIZE HAIL AS THEY MOVE EAST AT 20 MPH. BOYNE
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE LA CROSSE WI 307 PM CDT TUE JUL 20 2010 WIZ017-029-202100- CLARK-TAYLOR- 307 PM CDT TUE JUL 20 2010 ...STRONG THUNDERSTORMS CONTINUING TO DEVELOP ACROSS CLARK AND TAYLOR COUNTIES... THROUGH 4 PM...SCATTERED STRONG THUNDERSTORMS ARE EXPECTED TO CONTINUE TO DEVELOP AND MOVE EAST AT 25 MPH ACROSS NORTH CENTRAL WISCONSIN MAINLY NORTH OF WISCONSIN 29. A FEW OF THESE THUNDERSTORMS MAY BECOME SEVERE AND THEY WILL BE CAPABLE OF PRODUCING UP TO QUARTER SIZE HAIL AND WIND GUSTS TO 40 MPH. BOYNE
The La Crosse radar (KARX), 161 km away, was scanning. The volume nearest the first event began at 20:33 UTC.
2 thunderstorm wind, 1 hail. Local standard time, as filed.
Several large trees were blown down in the city of Medford.
Three trees were blown down along County Highway H south of Miller Avenue.
Hail fell in and around Gilman for about 5 minutes and ranged in size from three quarters of an inch up to 1.25 inches. The emergency manager reported some of the dime sized hail produced a swath of damage about a 1/2 mile wide and 4 miles long. Corn, beans and hay were stripped of their leaves and smashed down. The piles of hail along the roads in this area resembled plowed snow.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2010Every state in 2010This day in weather historyWarnings in Wisconsin, July 2010
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 244737, 244739, 244730.