A line of thunderstorms ahead of a cold front produced damaging winds across parts of southeast Minnesota in the late evening hours of August 3rd. These storms produced winds primarily below severe limits, but were strong enough around Mazeppa (Wabasha County) to blow down some trees.
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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.
A line of thunderstorms ahead of a cold front produced damaging winds across parts of southeast Minnesota in the late evening hours of August 3rd. These storms produced winds primarily below severe limits, but were strong enough around Mazeppa (Wabasha County) to blow down some trees.
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 Aug 3, 10:20 PM CST, 51 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 1120 PM CDT FRI AUG 3 2012 .SHORT TERM...TONIGHT 830 PM CDT FRI AUG 3 2012 A LINE OF THUNDERSTORMS...SOME SEVERE...WAS ADVANCING EASTWARD ACROSS WESTERN MINNESOTA THIS EVENING. AT ITS CURRENT SPEED IT WILL APPROACH AUSTIN AND ROCHESTER MN AROUND 1 AM. ABOUT 1500 J/KG OF MLCAPE TO WORK WITH ACROSS SOUTHEAST MN AS IT MOVES IN. THE LINE WILL BE MOVING OUT OF THE MORE FAVORABLE WIND SHEAR...BUT RAP13 SUGGESTS 25-30 KTS OF 0-3 KM SHEAR...WHICH WOULD BE ORTHOGONAL TO THE STORMS MOVEMENT...AND SUPPORT A SEVERE WIND THREAT. LATEST HRRR DOING A DECENT JOB WITH CAPTURING THE STORMS...AS DID THE 12Z ARW. BOTH BRING THE STORMS IN LATE THIS EVENING...DIMINISHING AS THEY MOVE EAST INTO WESTERN WI OVERNIGHT. THIS LOOKS REASONABLE AND HAVE ADJUSTED PCPN CHANCES TO REFLECT THE CURRENT/ANTICIPATED MOVEMENT. THERE DOES APPEAR TO BE A SEVERE THREAT AS IT MOVES INTO SOUTHEAST MN...BUT THIS ALSO SHOULD DIMINISH AS THEY MOVE EAST. WILL MONITOR CLOSELY. WITH SEVERE PARAMETERS DECREASING AS THE STORMS MOVE IN...DON/T ANTICIPATE A WATCH FROM SPC FOR THE FORECAST AREA AT THIS TIME...BUT NOT RULING OUT THE POSSIBILITY EITHER. IF CURRENT BOWING SEGMENTS IN THE LINE HOLD TOGETHER...ONE WOULD BE WARRANTED. .LONG TERM...TUESDAY THROUGH FRIDAY 311 PM CDT FRI AUG 3 2012 03.12 MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT TUESDAY THROUGH THURSDAY WITH AN ACTIVE WEATHER PATTERN SETTING UP FOR THE LATER PART OF NEXT WEEK. EMBEDDED SHORTWAVES...IN NORTHWEST FLOW ALOFT...WILL BRING CHANCES FOR SHOWERS AND THUNDERSTORMS WEDNESDAY THROUGH FRIDAY. PLAN ON TEMPERATURES RANGING ROM THE UPPER 70S TO AROUND 80 ACROSS NORTHERN WISCONSIN TO THE LOWER TO MIDDLE 80S OVER NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN. LOOK FOR OVERNIGHT LOWS TO RANGE FROM THE UPPER 50S TO LOWER 60S. && .AVIATION... 1120 PM CDT FRI AUG 3 2012 LINE OF CONVECTION CONTINUES TO TRACK EAST ACROSS MN LATE THIS EVENING...AND THIS WILL IMPACT KRST AND KLSE. AT ITS CURRENT PACE IT WILL REACH KRST BY 0530Z AND KLSE NEAR 07Z. THE STORMS ARE PACKING QUITE A BIT OF WIND...EXPECT NORTHWEST GUSTS UPWARDS OF 40 TO 50 KTS AT KRST...CLOSER TO 40 KTS AT KLSE. THE LINE SHOULD SWEEP EAST OF KRST BY 09Z AND KLSE BY 11Z. MORE SHRA/TS WILL MOVE IN LATER SAT MORNING...CONTINUING INTO THE AFTERNOON...AS A COLD FRONT DRIVES EAST ACROSS THE REGION. NAM12 BRINGS IT ACROSS KRST AROUND 16Z AND KLSE NEAR 18Z. SOME OF THESE STORMS COULD ALSO BECOME STRONG TO SEVERE...WITH WIND AND HAIL THE THREATS. THE GREATER THREAT WILL LIKELY BE AT KLSE WHERE TIMING WILL FAVOR MORE INSTABILITY...AND THUS THE POTENTIAL FOR STRONGER STORMS. EXPECT MOST OF THE ACTIVITY TO EXIT EAST BETWEEN 21-00Z...WITH A CLEARING TREND IN THE EVENING AS HIGH PRESSURE OVER THE PLAINS STARTS TO INFLUENCE THE LOCAL AREA. PRESSURE GRADIENT STAYS RELATIVELY TIGHT THOUGH...SO THERE MIGHT NOT BE A LOT OF DROP OFF IN WINDS SAT NIGHT. && .ARX WATCHES/WARNINGS/ADVISORIES... 311 PM CDT FRI AUG 3 2012 WI...NONE. MN...NONE. IA...NONE. && SHORT TERM...RIECK LONG TERM....WETENKAMP AVIATION.....RIECK
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LA CROSSE WI 1130 PM CDT FRI AUG 3 2012 IAZ010-011-029-030-MNZ096-WIZ041>044-053>055-061-041000- ADAMS-ALLAMAKEE-CLAYTON-CRAWFORD-FAYETTE-GRANT-HOUSTON-JUNEAU- LA CROSSE-MONROE-RICHLAND-VERNON-WINNESHIEK- 1130 PM CDT FRI AUG 3 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF NORTHEAST IOWA... SOUTHEAST MINNESOTA AND SOUTHWEST INTO NORTH CENTRAL WISCONSIN. .DAY ONE...OVERNIGHT THUNDERSTORMS WILL MOVE ACROSS PORTIONS OF THE AREA...WITH THE BULK OF THE STORMS NORTH OF INTERSTATE 90. SOME STRONG STORMS WILL BE POSSIBLE INITIALLY...CAPABLE OF WIND GUSTS UP TO 40 MPH. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY A VIGOROUS COLD FRONT WILL CROSS THE AREA SATURDAY...BRINGING PERIODS OF THUNDERSTORMS. THESE STORMS MAY BECOME SEVERE IN THE AFTERNOON AND EVENING BEFORE MOVING EAST AS THE FRONT SWEEPS THROUGH. THE MAIN SEVERE THREAT WOULD BE DAMAGING WINDS AND LARGE HAIL. THERE ARE ALSO THUNDERSTORM CHANCES MONDAY NIGHT AND AGAIN THURSDAY AND FRIDAY. AT THIS TIME...IT IS TOO EARLY TO DISCERN WHETHER THESE STORMS WILL BE SEVERE...BUT ORGANIZED SEVERE WEATHER APPEARS UNLIKELY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED OVERNIGHT...BUT MAY BE NEEDED SATURDAY AFTERNOON INTO THE EARLY EVENING. .EMERGENCY MANAGEMENT COORDINATION... NO WEBINAR IS SCHEDULED. MNZ079-086>088-WIZ017-029-032>034-041000- BUFFALO-CLARK-DODGE-JACKSON-OLMSTED-TAYLOR-TREMPEALEAU-WABASHA- WINONA- 1130 PM CDT FRI AUG 3 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF SOUTHEAST MINNESOTA AND WESTERN WISCONSIN. .DAY ONE...OVERNIGHT THUNDERSTORMS WILL TRACK ACROSS THE AREA...SOME OF WHICH WILL BE STRONG TO SEVERE. DAMAGING WINDS IN EXCESS OF 60 MPH WILL BE THE MAIN THREAT. THE STORMS SHOULD CLEAR SOUTHEAST MINNESOTA BY 2 AM... AND NORTHWEST WISCONSIN BY 4 AM. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY A VIGOROUS COLD FRONT WILL CROSS THE AREA SATURDAY...BRINGING PERIODS OF THUNDERSTORMS. IT APPEARS THE FRONT WILL MOVE EAST OF SOUTHEAST MINNESOTA EARLY ENOUGH TO LIMIT THE SEVERE STORM POTENTIAL THERE. THERE WILL BE A SLIGHT CHANCE FOR SEVERE WEATHER OVER WESTERN WISCONSIN. THERE ARE ALSO THUNDERSTORM CHANCES MONDAY NIGHT AND AGAIN THURSDAY AND FRIDAY. AT THIS TIME...IT IS TOO EARLY TO DISCERN WHETHER THESE STORMS COULD BECOME SEVERE...BUT ORGANIZED SEVERE WEATHER APPEARS UNLIKELY. .SPOTTER INFORMATION STATEMENT... A FEW SPOTTER GROUPS MAY BE NEEDED OVERNIGHT. .EMERGENCY MANAGEMENT COORDINATION... NO WEBINAR IS SCHEDULED. IAZ008-009-018-019-MNZ094-095-041000- CHICKASAW-FILLMORE-FLOYD-HOWARD-MITCHELL-MOWER- 1130 PM CDT FRI AUG 3 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA. .DAY ONE...OVERNIGHT THUNDERSTORMS WILL TRACK ACROSS THE AREA...SOME OF WHICH WILL BE STRONG CAPABLE OF WIND GUSTS UP TO 40 MPH. THE STORMS SHOULD CLEAR MOST OF THE AREA BY 2 AM. .DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY A VIGOROUS COLD FRONT WILL CROSS THE AREA SATURDAY...BRINGING PERIODS OF THUNDERSTORMS. IT APPEARS THE FRONT WILL MOVE EAST EARLY ENOUGH TO LIMIT THE SEVERE STORM POTENTIAL. THERE ARE ALSO THUNDERSTORM CHANCES MONDAY NIGHT AND AGAIN THURSDAY AND FRIDAY. AT THIS TIME...IT IS TOO EARLY TO DISCERN WHETHER THESE STORMS COULD BECOME SEVERE...BUT ORGANIZED SEVERE WEATHER APPEARS UNLIKELY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED .EMERGENCY MANAGEMENT COORDINATION... NO WEBINAR IS SCHEDULED. RIECK
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE LA CROSSE WI 1135 PM CDT FRI AUG 3 2012 MNZ079-086-087-040530- DODGE-OLMSTED-WABASHA- 1135 PM CDT FRI AUG 3 2012 ...STRONG TO SEVERE THUNDERSTORMS APPROACHING DODGE...OLMSTED AND WABASHA COUNTIES... AT 1132 PM...DOPPLER RADAR INDICATED STRONG TO SEVERE THUNDERSTORMS FROM 32 MILES NORTHWEST OF GILBERT VALLEY TO 15 MILES WEST OF RICE LAKE STATE PARK...MOVING EAST AT 45 MPH. WIND GUSTS UP TO 55 MPH...TORRENTIAL DOWNPOURS AND FREQUENT DANGEROUS LIGHTNING MAY ACCOMPANY THESE THUNDERSTORMS. LOCATIONS THAT MAY BE AFFECTED INCLUDE... WEST CONCORD...CLAREMONT...DODGE CENTER...MANTORVILLE AND MAZEPPA. A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 400 AM SATURDAY MORNING FOR SOUTHEAST MINNESOTA AND NORTHWESTERN WISCONSIN. PREPARE NOW FOR POSSIBLE STRONG TO DAMAGING THUNDERSTORM WIND GUSTS. MOVE INDOORS AND AWAY FROM WINDOWS IF A WARNING IS ISSUED. DTJ
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE LA CROSSE WI 1155 PM CDT FRI AUG 3 2012 MNZ079-087-088-WIZ017-029-032>034-040600- BUFFALO-CLARK-JACKSON-OLMSTED-TAYLOR-TREMPEALEAU-WABASHA-WINONA- 1155 PM CDT FRI AUG 3 2012 ...STRONG TO SEVERE THUNDERSTORMS APPROACHING... AT 1145 PM...A LINE OF STRONG TO SEVERE THUNDERSTORMS WAS MOVING ACROSS EASTERN MINNESOTA AND WILL EDGE INTO WESTERN WISCONSIN DURING THE EARLY MORNING HOURS. THESE STORMS ARE PRODUCING WIND GUSTS IN THE 40 TO 60 MPH RANGE ALONG WITH FREQUENT LIGHTNING AND HEAVY RAIN. THE MAIN THREAT WILL BE THE WIND GUSTS ON THE LEADING EDGE. BE CAREFUL NEAR TREES OR OTHER OBJECTS THAT COULD TOPPLE IN STRONGER WINDS. IF YOU ARE CAMPING...MOVE TO A STRONG SHELTER. A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 400 AM FOR MUCH OF THE AREA. SHEA
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE LA CROSSE WI 1200 AM CDT SAT AUG 4 2012 MNZ094-095-040700- FILLMORE-MOWER- 1200 AM CDT SAT AUG 4 2012 ...STRONG THUNDERSTORMS TO ROLL ACROSS THE AREA... STRONG THUNDERSTORMS CAPABLE OF WIND GUSTS OF 40 TO 50 MPH AND HEAVY DOWNPOURS WILL MOVE ACROSS THE AREA LATE TONIGHT. THE BULK OF THE STORMS WILL EXIT EAST BY 2 AM. RIECK
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
1202 AM CDT SAT AUG 04 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1154 PM TSTM WND GST DODGE CENTER 44.03N 92.85W
08/03/2012 M43 MPH DODGE MN AWOS
&&
SHEAPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
1211 AM CDT SAT AUG 04 2012
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1207 AM TSTM WND GST 2 NW ROCHESTER 44.03N 92.50W
08/04/2012 M50 MPH OLMSTED MN BROADCAST MEDIA
REPORTED FROM KTTC STUDIO ON NORTHWEST SIDE OF CITY
&&
SHEAThe Minneapolis radar (KMPX), 103 km away, was scanning. The volume nearest the first event began at 05:11 UTC.
1 thunderstorm wind. Local standard time, as filed.
Trees were blown down in Mazeppa.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Minnesota in 2012Every state in 2012This day in weather historyWarnings in Minnesota, August 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: 400501.