A couple rounds of thunderstorms moved across northeast Iowa during the late evening of July 25th. These storms brought damaging winds to the area that blew down trees from Nashua (Chickasaw County) east to Guttenberg (Clayton County) where a 64 mph wind gust was measured.
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.
A couple rounds of thunderstorms moved across northeast Iowa during the late evening of July 25th. These storms brought damaging winds to the area that blew down trees from Nashua (Chickasaw County) east to Guttenberg (Clayton County) where a 64 mph wind gust was measured.
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 25, 5:34 PM CST, 2 hours 1 minute earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LA CROSSE WI
634 PM CDT WED JUL 25 2012
.SHORT TERM...
630 PM CDT WED JUL 25 2012
MONITORING SEVERAL BOUNDARIES ON THE KARX RADAR AT THIS TIME
ASSOCIATED WITH COLD FRONT AND SLIGHT WIND SHIFT CONVERGENT
ZONES. HEART OF THE FORECAST AREA HAS BEEN UNDER THE MOST
OPPRESSIVE MID-LEVEL CAPPING TEMPERATURES /12-14C AT 700MB/ AND
FROM 00-06Z...MODEL GUIDANCE INDICATIONS ARE TO COOL THE MID-
LEVELS SOME TO ALLOW SOME DESTABILIZATION. CURRENT ANALYSIS OF
MLCAPES ALONG I-90 AND SOUTH ARE STILL OKAY...IN THE 1500 J/KG
RANGE. HOWEVER...NEED TO BE CAREFUL ON THIS ONE AS POST-FRONTAL
CAPES /MUCAPE/ OF 3000-4000 J/KG ARE OVER THE AREA AS OF
23Z...ABOVE THE FRONT. IN FACT...THIS MUCAPE POOL HAS 2K J/KG BACK
TO KMSP. SO...PLENTY TO WORK WITH FOR ENERGY.
MAIN TARGET WE THINK WILL BE THE WEATHER ACTIVITY COMING ACROSS
SRN MN AS AN INITIATION MECHANISM. WITH CAPE OUT IN FRONT OF THE
MID-LEVEL CIRCULATION E OF KFSD...EXPECT UPSCALE GROWTH AND
COVERAGE INCREASES OF TSRA OVER NEXT HOURS IS EXPECTED. HAVE MOVED THE
RAIN CHANCES FURTHER NW THIS EVENING TO COVER POST-FRONTAL REGIME.
VERY LOW CONFIDENCE ON JUST HOW MUCH TSRA COVERAGE WE WILL SEE
WITH THIS DIFFICULT SYSTEM TO FORECAST. THE CAP AND TEMPERATURE
REGIMES ARE MAKING IT TOUGH WORK. JUST LOOK TO WISCONSIN ECHOES
THAT DEVELOP BUT CANNOT GET GOING IN KEAU-KDLL AREA...A SIGN OF
THE MID-LEVEL WARMTH WINNING OUT.
MAIN THREATS WILL BE WIND DAMAGE FROM THE STORMS THIS EVENING. AND
IT IS IMPORTANT TO NOT USE THE COLD FRONT AS A NWRN LIMIT TO THE
SEVERE THREAT. WILL BE UPDATING THE HAZARDOUS WEATHER OUTLOOK TO
TRY AND WRITE SOMETHING INTELLIGENT ABOUT TIMING...BUT EVENING IS
THE MAIN SHOW.
WILL ALLOW HEAT ADVISORIES TO EXPIRE ON TIME.
.LONG TERM...SUNDAY THROUGH WEDNESDAY
245 PM CDT WED JUL 25 2012
LATER FORECAST PERIODS SUMMARIZED BY MEAN UPPER RIDGE REMAINING OVER
ROCKIES AND EVEN SOME SIGNALS THAT IT COULD BUILD EAST. WHILE MEDIUM
RANGE IN GOOD AGREEMENT WITH OVERALL PATTERN REGIME...NO SPECIFIC
FEATURES TO PUT HIGHER CONFIDENCE ON FOR RAIN CHANCES. WEAK SHORT
WAVE IMPULSES IN NORTHWEST FLOW COULD LEAD TO OCCASIONAL MCS OR
CONVECTIVE DEVELOPMENT BUT CONFIDENCE ON WHEN AND WHERE SKETCHY.
BY MID WEEK...WITH RIDGE BUILDING IN A LITTLE STRONGER...LEANING
MORE TOWARDS DRIER FORECASTS AND WARMING TREND WITH POSSIBLE RETURN
TO ADVISORY OR NEAR HEAT ADVISORY CRITERIA. OVERALL NOT IN THE WAY
OF CHANGE.
&&
.AVIATION...TONIGHT AND THURSDAY
630 PM CDT WED JUL 25 2012
INCREASING THREAT FOR THUNDER DURING THE EVENING HOURS AT THE TAF
SITES. A WEATHER SYSTEM SHIFTING ACROSS SRN MN AT 23Z WILL MOVE
ACROSS THE TAF SITES AND BRING A CHANCE OF TSRA. HAVE TRIED TO PUT
A FINITE WINDOW OF THIS THREAT IN THE TAFS USING VCTS. AN UPGRADE TO
INCLUDE A MORE SEVERE TSRA HIT AT THE AIRPORTS MAY BE NEEDED BASED
ON RADAR...AND WILL BE MONITORING. AT THIS TIME....CONVECTIVE
COVERAGE IS TOUGH TO DETERMINE OVER THE NEXT SEVERAL HOURS.
OTHERWISE...VFR EXPECTED IN NW SURFACE WINDS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
245 PM CDT WED JUL 25 2012
WI...HEAT ADVISORY THROUGH 9 PM CDT THIS EVENING FOR
WIZ054-055-061
HEAT ADVISORY THROUGH 7 PM CDT THIS EVENING FOR
WIZ041>044-053
MN...HEAT ADVISORY THROUGH 7 PM CDT THIS EVENING FOR
MNZ088-095-096
IA...HEAT ADVISORY THROUGH 9 PM CDT THIS EVENING FOR
IAZ010-011-018-019-029-030
HEAT ADVISORY THROUGH 7 PM CDT THIS EVENING FOR
&&
SHORT TERM...BAUMGARDT
LONG TERM....SHEA
AVIATION...BAUMGARDTHAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LA CROSSE WI 652 PM CDT WED JUL 25 2012 WIZ017-029-261100- CLARK-TAYLOR- 652 PM CDT WED JUL 25 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL WISCONSIN. .DAY ONE...TONIGHT A FEW SHOWERS AND THUNDERSTORMS WILL BE AROUND DURING THE EVENING. THESE STORMS ARE NOT EXPECTED TO BE SEVERE. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THUNDERSTORMS ARE POSSIBLE AGAIN ON THURSDAY...MAINLY IN THE AFTERNOON. ISOLATED SEVERE WEATHER IS POSSIBLE. DAMAGING WINDS AND LARGE HAIL WOULD BE THE PRIMARY HAZARDS. THERE ARE ADDITIONAL CHANCES FOR THUNDERSTORMS THURSDAY NIGHT INTO FRIDAY. SEVERE WEATHER IS NOT EXPECTED. THUNDERSTORM CHANCES RETURN SATURDAY NIGHT THROUGH TUESDAY. IT IS TOO EARLY TO DETERMINE IF THERE IS A SEVERE WEATHER THREAT WITH ANY OF THESE STORMS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS UNLIKELY THIS EVENING. .EMERGENCY MANAGEMENT COORDINATION... NO WEBINAR IS SCHEDULED. IAZ008-009-MNZ079-086>088-094>096-WIZ032>034-041>044-053-261100- ADAMS-BUFFALO-DODGE-FILLMORE-HOUSTON-HOWARD-JACKSON-JUNEAU-LA CROSSE- MITCHELL-MONROE-MOWER-OLMSTED-TREMPEALEAU-VERNON-WABASHA-WINONA- 652 PM CDT WED JUL 25 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR A PART OF SOUTHEAST MINNESOTA...PORTIONS OF NORTHEAST IOWA...AND SOUTHWEST INTO CENTRAL WISCONSIN. .DAY ONE...TONIGHT SHOWERS AND THUNDERSTORMS WILL BE ON THE INCREASE TONIGHT FROM WEST TO EAST AS A WEATHER SYSTEM MOVES THROUGH. STORMS WILL MOVE INTO NORTHEAST IOWA AND SOUTHEAST MINNESOTA DURING THE MID-EVENING...AND THEN SHIFT EAST INTO WESTERN AND CENTRAL WISCONSIN BY LATER EVENING. IT IS DIFFICULT TO DISCERN HOW WIDESPREAD THE STORMS WILL BE...BUT THE STRONGER STORMS CAN CERTAINLY PRODUCE DAMAGING WINDS AND LARGE HAIL. THE MAIN ACTIVITY SHOULD WEAKEN OR MOVE EAST AFTER MIDNIGHT. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THUNDERSTORMS ARE POSSIBLE AGAIN ON THURSDAY...MAINLY IN THE AFTERNOON. ISOLATED SEVERE WEATHER IS POSSIBLE ALONG AND EAST OF THE MISSISSIPPI RIVER. DAMAGING WINDS AND LARGE HAIL WOULD BE THE PRIMARY HAZARDS. THERE ARE ADDITIONAL CHANCES FOR THUNDERSTORMS THURSDAY NIGHT INTO FRIDAY. SEVERE WEATHER IS NOT EXPECTED. THUNDERSTORM CHANCES RETURN SATURDAY NIGHT THROUGH TUESDAY. IT IS TOO EARLY TO DETERMINE IF THERE IS A SEVERE WEATHER THREAT WITH ANY OF THESE STORMS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED AROUND MID-EVENING IN NORTHEAST IOWA AND SOUTHEAST MINNESOTA...AND IN THE LATER EVENING IN WESTERN AND CENTRAL WISCONSIN. SPOTTER ACTIVATION MAY ONLY BE LOCALIZED SHOULD A LOWER COVERAGE OF THUNDERSTORMS DEVELOP. .EMERGENCY MANAGEMENT COORDINATION... NO WEBINAR IS SCHEDULED. IAZ010-011-018-019-029-030-WIZ054-055-061-261100- ALLAMAKEE-CHICKASAW-CLAYTON-CRAWFORD-FAYETTE-FLOYD-GRANT-RICHLAND- WINNESHIEK- 652 PM CDT WED JUL 25 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST IOWA... AND SOUTHWEST WISCONSIN. .DAY ONE...TONIGHT HEAT WILL CONTINUE INTO THE EVENING AND A HEAT ADVISORY IS IN EFFECT UNTIL 9 PM THIS EVENING. SHOWERS AND THUNDERSTORMS WILL BE ON THE INCREASE TONIGHT FROM WEST TO EAST AS A WEATHER SYSTEM MOVES THROUGH. STORMS WILL MOVE INTO NORTHEAST IOWA AROUND MID-EVENING...AND THEN SHIFT EAST INTO SOUTHWEST WISCONSIN BY LATE EVENING. IT IS DIFFICULT TO DISCERN HOW WIDESPREAD THE STORMS WILL BE...BUT THE STRONGER STORMS CAN CERTAINLY PRODUCE DAMAGING WINDS AND LARGE HAIL. THE MAIN ACTIVITY SHOULD WEAKEN OR MOVE EAST AFTER MIDNIGHT. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THUNDERSTORMS ARE POSSIBLE AGAIN ON THURSDAY...MAINLY IN THE AFTERNOON. ISOLATED SEVERE WEATHER IS POSSIBLE ALONG AND EAST OF THE MISSISSIPPI RIVER. DAMAGING WINDS AND LARGE HAIL WOULD BE THE PRIMARY HAZARDS. THERE ARE ADDITIONAL CHANCES FOR THUNDERSTORMS THURSDAY NIGHT INTO FRIDAY. SEVERE WEATHER IS NOT EXPECTED. THUNDERSTORM CHANCES RETURN SATURDAY NIGHT THROUGH TUESDAY. IT IS TOO EARLY TO DETERMINE IF THERE IS A SEVERE WEATHER THREAT WITH ANY OF THESE STORMS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED AROUND MID-EVENING IN NORTHEAST IOWA...AND CLOSER TO MIDNIGHT IN SOUTHWEST WISCONSIN. SPOTTER ACTIVATION MAY ONLY BE LOCALIZED SHOULD A LOWER COVERAGE OF THUNDERSTORMS DEVELOP. .EMERGENCY MANAGEMENT COORDINATION... NO WEBINAR IS SCHEDULED. DAS/WETENKAMP/BAUMGARDT
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE LA CROSSE WI 642 PM CDT WED JUL 25 2012 MNZ094-260045- MOWER- 642 PM CDT WED JUL 25 2012 AT 634 PM...DOPPLER RADAR INDICATED A LINE OF STRONG THUNDERSTORMS FROM NEAR GENEVA AND ALBERT LEA IN FREEBORN COUNTY...MOVING EAST AT 35 TO 40 MPH. WIND GUSTS OF TO 40 MPH...SMALL HAIL...AND TORRENTIAL DOWNPOURS MAY ACCOMPANY THESE STRONG THUNDERSTORMS AS THEY MOVE INTO MOWER COUNTY BY 7 PM. LOOK FOR THESE STORMS TO CONTINUE MOVING EAST THROUGH MOWER COUNTY THROUGH 745 PM. LOCATIONS THAT MAY BE AFFECTED INCLUDE... AUSTIN...BROWNSDALE...LYLE...ROSE CREEK...GRAND MEADOW AND ADAMS. DAS
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE LA CROSSE WI 825 PM CDT WED JUL 25 2012 IAZ018-019-029-030-260215- CHICKASAW-CLAYTON-FAYETTE-FLOYD- 825 PM CDT WED JUL 25 2012 ...STRONG TO SEVERE THUNDERSTORMS APPROACHING NORTHEAST IOWA... AT MID EVENING...STRONG TO SEVERE THUNDERSTORMS WERE DEVELOPING BETWEEN DES MOINES...MASON CITY AND WATERLOO IOWA. SOME OF THESE STORMS HAVE A HISTORY OF LARGE HAIL AND DAMAGING WIND GUSTS... IN ADDITION TO HEAVY RAIN AND FREQUENT LIGHTNING. THEY ARE TRACKING EAST TO SOUTHEAST AND COULD AFFECT THE COMMUNITIES OF MARBLE ROCK...NASHUA...OELWEIN...STANLEY...STRAWBERRY POINT AND EDGEWOOD OVER THE NEXT 1 TO 2 HOURS. STORMS ALONG AND NORTH OF HIGHWAY 18 IN NORTHEAST IOWA WILL MOST LIKELY NOT BE IMPACTED BY THESE STRONGER STORMS. AS STORMS TRACK INTO YOUR AREA TONIGHT...MOVE INDOORS. STAY AWAY FROM TREES OR LIMBS THAT COULD BREAK IN HIGH WIND. CANCEL EVENING ACTIVITIES BECAUSE OF THE LIGHTNING RISK. HEAVY RAIN COULD LEAD TO MINOR FLOODING OR A SHORT PERIOD OF STANDING WATER. STAY CLEAR OF DRAINAGE AREAS AND AVOID AREAS OF HIGH WATER IF THEY DEVELOP. SHEA
SPECIAL WEATHER STATEMENT...CORRECTED NATIONAL WEATHER SERVICE LA CROSSE WI 827 PM CDT WED JUL 25 2012 IAZ018-019-029-030-260215- CHICKASAW-CLAYTON-FAYETTE-FLOYD- 827 PM CDT WED JUL 25 2012 ...STRONG TO SEVERE THUNDERSTORMS APPROACHING NORTHEAST IOWA... AT MID EVENING...STRONG TO SEVERE THUNDERSTORMS WERE DEVELOPING BETWEEN DES MOINES...MASON CITY AND WATERLOO IOWA. SOME OF THESE STORMS HAVE A HISTORY OF LARGE HAIL AND DAMAGING WIND GUSTS... IN ADDITION TO HEAVY RAIN AND FREQUENT LIGHTNING. THEY ARE TRACKING EAST TO SOUTHEAST AND COULD AFFECT THE COMMUNITIES OF MARBLE ROCK...NASHUA...OELWEIN...STANLEY...STRAWBERRY POINT AND EDGEWOOD OVER THE NEXT 1 TO 2 HOURS. CITIES ALONG AND NORTH OF HIGHWAY 18 IN NORTHEAST IOWA WILL MOST LIKELY NOT BE IMPACTED BY THESE STRONGER STORMS. AS STORMS TRACK INTO YOUR AREA TONIGHT...MOVE INDOORS. STAY AWAY FROM TREES OR LIMBS THAT COULD BREAK IN HIGH WIND. CANCEL EVENING ACTIVITIES BECAUSE OF THE LIGHTNING RISK. HEAVY RAIN COULD LEAD TO MINOR FLOODING OR A SHORT PERIOD OF STANDING WATER. STAY CLEAR OF DRAINAGE AREAS AND AVOID AREAS OF HIGH WATER IF THEY DEVELOP. SHEA
The La Crosse radar (KARX), 106 km away, was scanning. The volume nearest the first event began at 01:36 UTC.
6 thunderstorm wind, 2 heavy rain, 2 hail. Local standard time, as filed.
In a little over 2 hours from two different rounds of thunderstorms, 4 inches of rain fell in Garnavillo.
Numerous trees and power lines were blown down across the southern sections of Clayton County.
A wind gust of 64 mph occurred in Guttenberg along with penny sized hail.
Trees were blown down in Nashua. The wind also blew out a window of a home and caused power outages.
In about 45 minutes, two inches of rain fell in Oelwein which produced some minor ponding of water on some city streets.
Numerous trees and power lines were blown down in Hawkeye.
Numerous trees and power lines were blown down across West Union.
A few trees were blown down in Edgewood.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2012Every state in 2012This day in weather historyWarnings in Iowa, 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: 396191, 395746, 395727, 395728, 395730, 395740, 395731, 395734, 395737, 396193.