Severe thunderstorms developed rapidly during the late morning and afternoon along and behind a slow moving cold front. These thunderstorms initially developed over Minnesota, moved southeast into northeast Iowa before tracking across southwest Wisconsin where they produced some wind damage.
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.
Severe thunderstorms developed rapidly during the late morning and afternoon along and behind a slow moving cold front. These thunderstorms initially developed over Minnesota, moved southeast into northeast Iowa before tracking across southwest Wisconsin where they produced some wind damage. Trees and power lines were blown down from Ferryville (Crawford County) east through Richland Center (Richland County) including a 72 mph gust in Prairie du Chien (Crawford County).
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 18, 2:30 PM CST, 1 hour 7 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 330 PM CDT WED JUL 18 2012 .SHORT TERM... 330 PM CDT WED JUL 18 2012 MOST OF THE TIME FORECASTING WAS SPENT ON THE CONVECTIVE THREATS OVERNIGHT AND INTO THURSDAY MORNING WITH RIDGE BUILDING AND QUITE WEATHER BEYOND. OBSERVATIONAL DATA QUITE IMPRESSIVE WITH WATER VAPOR SHORTWAVE SIGNALS OVER THE DAKOTAS...WITH DRYING AND SUBSIDENCE CLEARLY SEEN BEHIND THE WAVE. OLD OUTFLOW BOUNDARY IS ORIENTED ALONG A KMSN-KPDC-KMCW LINE AT 20Z. ANOTHER BOUNDARY EXTENDS FROM KISW TO KAUM FROM NORTHERN CONVECTION THIS AFTERNOON/MORNING. RADAR INDICATES TWO TIGHT SPINS MOVING INTO THE AREA...EAST OF KFSD AND NEAR KMCW AT 20Z AND RADAR IS ENHANCING AS THESE APPROACH THE INSTABILITY PRESENT...AND INTERACT WITH SURFACE CONVERGENT BOUNDARIES. 12Z RAOB DATA SUGGESTS AN INTENSE LOW-LEVEL THERMAL GRADIENT IS IN PLACE FROM ABOUT KDBQ-KGRB WITH KDVN-KGRB 925 MB TEMPERATURE DIFFERENCE OF 13C AT 12Z. FRONTAL SLOPE NEWRD PLACES A NICE 800-925 MB FRONTAL SURFACE SLOPE ACROSS THE NE 2/3RDS OF THE FORECAST AREA. LATEST MODEL ANALYSIS /RAP/ SUGGESTING FRONTOGENESIS IS ACTIVE IN THIS ZONE AND SENSIBLE WEATHER IS THE CONVECTION ON RADAR ALONG THIS ZONE...LIFTING NORTH AND DIMINISHING. OVERALL CONSENSUS OF MODELS IS RAINFALL OVER THE AREA WITH THE FRONTAL BOUNDARY IN THE NORTHERN FORECAST AREA AND THE BOUNDARIES AND MESOSCALE CONVECTIVE VORTICIES /MVCS/ BRINGING SOME DYNAMICS TO THE FORECAST AREA. THE FRONTOGENESIS HAS SHIFTED NORTH THIS AFTERNOON INTO NRN WI BUT UPSTREAM SHORTWAVE ENERGY MOVING IN FROM THE DAKOTAS COULD AGAIN ACTIVATE THIS AREA. MOST OF THE ISENTROPIC LIFT AND CONVECTIVE ACTIVITY SHOULD OCCUR PRIOR TO 03Z WITH SHOWERY RAIN AND ISOLATED THUNDER AFTER THAT TIME FRAME. SEVERE WEATHER CHANCES THROUGH THE EVENING WILL KEY ON THE TWO TIGHT SPINNING MESOSCALE CONVECTIVE VORTICIES SHIFTING THROUGH AND WORKING WITH SURFACE BOUNDARIES AND INSTABILITY IN PLACE. MLCAPE IS HIGHEST ALONG THE I-90 CORRIDOR /2500 J/KG/ WITH LOWER VALUES HEADING INTO SWRN WI. LOW-LEVEL LAPSE RATES ARE VERY STEEP AND WITH THE MCVS PROVIDING AN ORGANIZING COMPONENT TO THE COLD POOL DOMINATED CONVECTION NEAR I-35...A LINEAR DAMAGING WIND PRODUCING SYSTEM IS EXPECTED. DEPENDING ON HOW WELL THE SYSTEM CAN MAINTAIN ITSELF IN WEAKER DEEP SHEAR...IT IS POSSIBLE TO SEE SOME ISOLATED GUSTS TO 65 MPH. 0-3KM SHEAR IS MODERATE TO ASSIST IN COLD POOL PROCESSES. WOULD THINK THE MAIN TRACK WOULD BE KMCW TO KISW THROUGH EARLY EVENING. HAIL IS ANOTHER THREAT BUT THIS SHOULD BE ISOLATED AND MAINLY EARLY /3-5 PM/ AS SYSTEM ORGANIZES. ON THURSDAY THE RIDGING WILL BUILD INTO THE AREA WITH A SLOWLY CLEARING SKY AND COOLER TEMPERATURES. WITH A 5C DROP IN THE 925 MB TEMPERATURES FROM TODAY PER 18.12Z NAM/ECMWF...THOUGHT WE WERE FORECASTING TOO WARM THURSDAY SO HAVE LOWERED HIGHS ABOUT 5F. HAVE ALSO COOLED THE HIGHS A BIT FRI/SAT. GOOD AGREEMENT ON A STRONGER SHORTWAVE TROUGH MOVING THROUGH SATURDAY BUT ONLY IN THE MID- UPPER TROPOSPHERE. THUS...ONLY MID-LEVEL CLOUDS ARE THE RESULT...BUT THIS MAY KEEP HIGHS COOLER THAN CURRENT FORECAST. IT APPEARS ONLY RAIN CHANCES WOULD BE VERY FAR NORTH. .LONG TERM... 330 PM CDT WED JUL 18 2012 THIS PERIOD IS AGAIN DOMINATED BY UPPER LEVEL RIDGING. CONSENSUS IS FOR AN ABOVE NORMAL WARM PERIOD WITH ONLY MINOR RAIN CHANCES. HIGH TEMPERATURES IN THE 90-100F RANGE AGAIN LOOK LIKELY. THERE IS SOME BUILDING MODEL CONSENSUS IN THE IDEA OF A COOLING AND MORE SIGNIFICANT LARGE SCALE TROUGH BUILDING INTO THE GREAT LAKES BY MID-WEEK AND COOLER CONDITIONS WITH BETTER RAIN CHANCES. && .AVIATION...THROUGH 18Z THURSDAY 1240 PM CDT WED JUL 18 2012 WATER VAPOR IMAGERY SHOWING A TROUGH OF LOW PRESSURE OVER THE DAKOTAS/NEBRASKA...MOVING EAST TOWARD THE AREA. LIFT AHEAD OF THIS WAVE EXPECTED TO KICK OFF/INCREASE CONVECTION ACROSS THE AREA THROUGH THIS AFTERNOON AND INTO THIS EVENING. SOME OF THIS CONVECTION COULD BECOME STRONG TO SEVERE BETWEEN 3 PM AND 8 PM GENERALLY ALONG AND SOUTH OF I-90 ACROSS MINNESOTA INTO WISCONSIN. DAMAGING WIND WOULD BE THE MAIN THREAT. LOOKING FOR A GENERAL DECREASE IN SHRA/TS COVERAGE AFTER MIDNIGHT AS THE TROUGH AXIS SHIFTS EAST OF THE AREA. HOWEVER...SOME LINGERING SHRA/TS EXPECTED TO CONTINUE AFTER MIDNIGHT WITH FAIRLY STEEP LAPSE RATES STILL OVERHEAD. MODELS THEN INDICATE BROKEN DECK OF MVFR CLOUD AFTER 09Z AS THE BOUNDARY LAYER COOLS BEHIND THE DEPARTING WAVE. EXPECTING THIS MVFR CLOUD COVER TO LINGER THROUGH THURSDAY MORNING..THEN SCOURING OUT BY AFTERNOON AS HIGH PRESSURE BUILDS IN. && .ARX WATCHES/WARNINGS/ADVISORIES... 330 PM CDT WED JUL 18 2012 WI...NONE. MN...NONE. IA...NONE. && SHORT TERM...BAUMGARDT LONG TERM...BAUMGARDT AVIATION...DAS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LA CROSSE WI 1244 PM CDT WED JUL 18 2012 WIZ017-029-191100- CLARK-TAYLOR- 1244 PM CDT WED JUL 18 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF NORTH CENTRAL WISCONSIN. .DAY ONE...THIS AFTERNOON AND TONIGHT SCATTERED THUNDERSTORMS WILL CONTINUE INTO THIS EVENING. BESIDES PERIODIC HEAVY RAIN...A FEW STRONGER STORMS COULD PRODUCE GUSTY WIND AS THEY MOVE THROUGH. LOCALIZED RAINFALL COULD ALSO REACH 1 TO 1.5 INCHES DEPENDING ON HOW THE STORMS TRACK. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY ADDITIONAL THUNDERSTORMS COULD BE IN THE AREA EARLY ON THURSDAY BUT THE SEVERE WEATHER RISK DOES NOT LOOK FAVORABLE. THERE ARE ALSO SMALL THUNDERSTORM CHANCES FROM THE WEEKEND INTO EARLY NEXT WEEK BUT THE RISK OF ANY WIDESPREAD SEVERE WEATHER LOOKS LOW. .SPOTTER INFORMATION STATEMENT... WIDESPREAD SPOTTER ACTIVATION IS NOT LOOKING FAVORABLE BUT ANY REPORTS OF HAIL OR GUSTY WINDS...IN ADDITION TO RAINFALL TOTALS... WOULD BE APPRECIATED. .EMERGENCY MANAGEMENT COORDINATION... NO WEBINAR IS SCHEDULED. IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ032>034-041>044- 053>055-061-191100- ADAMS-ALLAMAKEE-BUFFALO-CHICKASAW-CLAYTON-CRAWFORD-DODGE-FAYETTE- FILLMORE-FLOYD-GRANT-HOUSTON-HOWARD-JACKSON-JUNEAU-LA CROSSE- MITCHELL-MONROE-MOWER-OLMSTED-RICHLAND-TREMPEALEAU-VERNON-WABASHA- WINNESHIEK-WINONA- 1244 PM CDT WED JUL 18 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND SOUTHWEST INTO CENTRAL WISCONSIN. .DAY ONE...THIS AFTERNOON AND TONIGHT HOT TEMPERATURES WILL IMPACT MAINLY NORTHEAST IOWA AND NEIGHBORING AREAS WITH HEAT INDEX READINGS IN THE 95 TO 105 RANGE INTO THE EVENING. PRECAUTIONS FOR HEAT SHOULD BE USED. THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER PARTS OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA THIS AFTERNOON...AND COULD SPREAD MORE INTO WESTERN WISCONSIN BY EVENING. STORMS HAVE A THREAT FOR LOCALLY HEAVY RAIN...HAIL AND DAMAGING WINDS INTO TONIGHT. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THERE COULD BE LINGERING THUNDERSTORMS EARLY THURSDAY BUT SEVERE WEATHER IS NOT EXPECTED AT THIS TIME. THERE ARE ALSO SMALL STORM CHANCES THIS WEEKEND INTO EARLY NEXT WEEK BUT THE OVERALL RISK OF WIDESPREAD SEVERE WEATHER APPEARS LOW. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED AT TIMES THIS AFTERNOON AND INTO THE EVENING. PEAK WIND GUSTS OR ANY OBSERVED DAMAGE REPORTS WOULD BE USEFUL...IN ADDITION TO HAIL OR RAINFALL TOTALS. .EMERGENCY MANAGEMENT COORDINATION... NO WEBINAR IS SCHEDULED. SHEA
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
348 PM CDT WED JUL 18 2012
...TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
...DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0250 PM TSTM WND DMG SPRING VALLEY 43.69N 92.39W
07/18/2012 FILLMORE MN EMERGENCY MANAGER
SIX THREE FOOT DIAMETER TREES DOWN. PARK
PAVILION AND APARTMENT BUILDING DAMAGED.
&&
IRIS SYSTEMPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
359 PM CDT WED JUL 18 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0324 PM HAIL 3 W FREDERICKSBURG 42.96N 92.26W
07/18/2012 E1.50 INCH CHICKASAW IA PUBLIC
&&
ADAMSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
408 PM CDT WED JUL 18 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0340 PM TSTM WND DMG HESPER 43.48N 91.79W
07/18/2012 WINNESHIEK IA LAW ENFORCEMENT
TREES DOWN IN TOWN.
&&
ADAMSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
414 PM CDT WED JUL 18 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0400 PM TSTM WND GST DECORAH 43.31N 91.79W
07/18/2012 E50 MPH WINNESHIEK IA PUBLIC
&&
ADAMSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
418 PM CDT WED JUL 18 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0415 PM TSTM WND GST DORCHESTER 43.47N 91.52W
07/18/2012 E45 MPH ALLAMAKEE IA CO-OP OBSERVER
COUPLE OF 6 INCH DIAMETER TREE BRANCHES DOWN.
&&
ADAMSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
425 PM CDT WED JUL 18 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0420 PM HEAVY RAIN DECORAH 43.31N 91.79W
07/18/2012 M1.50 INCH WINNESHIEK IA PUBLIC
HOUR RAINFALL TOTAL.
&&
ADAMSThe La Crosse radar (KARX), 54 km away, was scanning. The volume nearest the first event began at 21:38 UTC.
5 thunderstorm wind, 1 flash flood, 1 heavy rain, 1 flood. Local standard time, as filed.
Trees and power lines were blown down in Ferryville.
Locally heavy rain from thunderstorms produced a rock slide that covered State Highway 35 north of Lynxville.
Trees and power lines were blown down in Seneca and other parts of western Crawford County.
Trees and power lines were blown down across Prairie du Chien.
Trees were blown down onto at least two homes in Mt. Zion.
In about an hour and a half, 2.68 inches of rain fell in La Farge.
Trees were blown down or snapped off in Richland Center including some three foot diameter trees snapped 8 to 12 feet above the ground.
Some street flooding occurred in Viroqua.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Wisconsin in 2012Every state in 2012This day in weather historyWarnings in Wisconsin, July 2012
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: 394768, 394767, 394773, 394775, 394778, 394808, 394776, 394782.