A slow moving cold front triggered thunderstorms across parts of northeast Iowa during the morning hours of August 27. A couple of the storms produced hail the size of ping-pong balls.
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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 slow moving cold front triggered thunderstorms across parts of northeast Iowa during the morning hours of August 27. A couple of the storms produced hail the size of ping-pong balls.
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 27, 1:35 AM CST, 2 hours 5 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 235 AM CDT MON AUG 27 2007 .SHORT TERM...TODAY THROUGH WEDNESDAY FORECAST CONCERNS HINGE ON THE PCPN CHANCES OVER THE NEXT FEW DAYS. CURRENTLY...THERE ARE TWO AREAS OF CONVECTION ACROSS THE REGION. ONE WAS ALONG FRONTAL BOUNDARY OVER NORTHERN MN...ENHANCED BY THE LOW LEVEL JET/MOISTURE TRANSPORT INTO THIS AREA. CORFIDI VECTORS WOULD TAKE THIS CONVECTION SOUTHEAST THIS MORNING...BUT THIS ACTIVITY IS EXPECTED TO DIE OUT BEFORE IT CAN REACH THE FORECAST AREA. ANOTHER AREA WAS MOVING EAST NORTHEAST ACROSS THE FORECAST. BOTH THE NAM AND THE GFS INDICATED THIS IN PREVIOUS MODEL RUNS...WITH A SEPARATE TONGUE OF MOISTURE ADVECTION AND THE LOW LEVEL JET POINTING INTO WESTERN WI. THIS IS RIGHT THROUGH A STRONG AREA OF 850 MB TEMP ADVECTION AND 850 MB THETA-E ADVECTION. THIS HAS BEEN ENOUGH TO KICK OFF CONVECTION...AND WILL KEEP SMALL POPS FOR EARU THIS MORNING AS A RESULT. THE FORCING WEAKENS BY THE AFTERNOON...PLUS THE FORECAST SOUNDINGS CONTINUE A RATHER HEFTY INVERSION...SO DON/T EXPECT THE PCPN TO LINGER INTO THE AFTERNOON. TONIGHT THROUGH TUESDAY NIGHT...THAT FRONTAL BOUNDARY WILL CONTINUE TO INCH EASTWARD...EXTENDING FROM NORTHEAST WI INTO WESTERN IA BY TUES AFTERNOON. BITS OF SHORTWAVE ENERGY WILL SPIN OUT OF THE CENTRAL ROCKIES TODAY...WORKING ON THIS BOUNDARY TONIGHT AND TUES. THE JET AND 850 MOISTURE TRANSPORT REESTABLISH THEMSELVES INTO NORTHERN WI TONIGHT...WHILE 850 MB TEMPS CONTINUE TO CLIMB //FROM 19 C THIS MORNING TO 23 C BY 12Z TUES//. DECENT STABLE LAYER FROM ABOUT 850 MB TO THE SFC AS A RESULT...ALTHOUGH SOME CAPE TO WORK WITH ABOVE THAT LAYER. OVERALL...THE BETTER FORCING SIGNALS FOR TONIGHT ARE ACROSS MN/NORTHERN WI...AND THIS IS WHERE THE BEST SHOWER/STORM CHANCES SHOULD BE. ON TUESDAY...INSTABILITY WILL CONTINUE TO INCREASE AHEAD OF THE SFC FRONT //SBCAPES APPROACHING 3000 J/KG//...WITH ABOUT 30 KTS OF 0-3 KM SHEAR. WOULD EXPECT THE FRONT TO BECOME MORE ACTIVE TUES AFTERNOON AS A RESULT. THINK THERE COULD BE SOME SEVERE POSSIBILITIES...ALTHOUGH HOW GREAT A CHANCE IS UNCERTAIN AT THE MOMENT. PROBABLY OF BIGGER CONCERN FOR THE LOCAL AREA IS IF THERE IS A THREAT FOR HEAVY RAIN. PW/S APPROACH 2 INCHES AGAIN...BUT THIS TIME AROUND THE LOW LEVEL MOISTURE TRANSPORT IS NOT AS STRONG AS WITH THE FLOODING RAINS OF LAST WEEKEND. THERE IS SOME FRONTOGENETIC FORCING THROUGH THE LAYERS...BUT MORE TRANSITORY WITH THE SFC FRONT...IT DOES NOT SIT STATIONARY LIKE LAST WEEKEND. SO...THERE COULD BE SOME BRIEF PERIODS OF HEAVY RAIN WITH ANY THUNDERSTORM THAT DEVELOPS...BUT DON/T BELIEVE TRAINING WILL BE A SIGNIFICANT ISSUE...WHICH SHOULD KEEP THE FLASH FLOODING POTENTIAL TO A MINIMUM. STILL...THE GROUNDS ARE VERY WET ACROSS THE FORECAST AREA...SO THIS WILL HAVE TO BE MONITORED CLOSELY. ON WEDNESDAY...A SFC HIGH LOOKS TO BUILD IN FROM THE NORTHERN PLAINS AS THAT FRONT CONTINUES TO SINK SOUTH. DECREASING CLOUDS CAN BE EXPECTED...ALTHOUGH SOME PCPN CHANCES MAY LINGER IN THE FAR SOUTH EARLY IN THE DAY. .LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY MEDIUM RANGE MODELS IN PRETTY GOOD AGREEMENT WITH A ZONAL UPPER LEVEL FLOW PATTERN INTO THE UPCOMING WEEKEND...WITH TEMPERATURES NEAR OR A BIT ABOVE THE SEASONABLE NORMALS. CURRENTLY...THE BULK OF THE SHORTWAVE ACTIVITY IS PROGGED TO STAY WELL NORTH...ACROSS SOUTHERN CANADA. AT THE SFC...BOTH THE GFS AND ECMWF BUILD IN AN AREA OF HIGH PRESSURE WEDNESDAY...WHICH THEN LOOKS TO HANG AROUND THE GREAT LAKES INTO SATURDAY. BY SUNDAY...THERE ARE SOME HINTS OF A FRONTAL BOUNDARY TRYING TO MAKE ITS WAS SOUTHWARD ACROSS THE UPPER MISSISSIPPI RIVER VALLEY...WHICH COULD BRING A SHOT FOR SOME SHOWER/STORMS. RELATIVELY WEAK SIGNAL AT THE MOMENT...WITH AGAIN...THE BEST UPPER LEVEL FORCING LOCATED TO THE NORTH. OVERALL...ITS SHAPING UP TO BE A DRY PERIOD FOR THE END OF THE WORK WEEK AND INTO THE WEEKEND. && .AVIATION... SCATTERED THUNDERSTORMS EXPECTED TO EXIT EARLY THIS MORNING. STRONG SOUTHERLY FLOW WILL BE THE RULE TODAY...WITH GUSTY WINDS AT BOTH KLSE AND KRST TAF SITES. VFR CONDITIONS ANTICIPATED TO LINGER INTO TONIGHT...WITH THUNDERSTORM ACTIVITY FOCUSED MAINLY NORTH AND WEST OF BOTH TAF SITES ALONG COLD FRONT. THOMPSON && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && RIECK
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LA CROSSE WI 500 AM CDT SUN AUG 26 2007 IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029-032>034- 041>044-053>055-061-271000- 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- 500 AM CDT SUN AUG 26 2007 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF SOUTHEAST MINNESOTA... NORTHEAST IOWA...AND FROM WEST INTO CENTRAL WISCONSIN. .DAY ONE...TODAY AND TONIGHT FAVORABLE LOW LEVEL MOISTURE RETURN WILL LEAD TO SOME SHOWER AND THUNDERSTORM DEVELOPMENT LATE TONIGHT...MOSTLY AFTER MIDNIGHT AND WEST OF THE MISSISSIPPI RIVER. SMALL HAIL WILL POSSIBLE WITH THE STRONGER STORMS...BUT ARE NOT EXPECTED TO REACH SEVERE LIMITS. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY A COLD FRONT WILL TRACK ACROSS THE UPPER MISSISSIPPI RIVER VALLEY ON MONDAY NIGHT AND TUESDAY...LINGERING ACROSS PARTS OF THE REGION ON WEDNESDAY. MOISTURE WILL SURGE OUT AHEAD AND INTO THIS BOUNDARY...AIDING IN SHOWER AND THUNDERSTORM DEVELOPMENT. INSTABILITY WILL BE ON THE INCREASE...ALTHOUGH THE BETTER WIND PROFILES WILL BE LOCATED BEHIND THE FRONT. SOME HEAVY RAIN DOES LOOK POSSIBLE AT THIS TIME...ALONG WITH THE POTENTIAL FOR SMALL HAIL. HOWEVER...ITS STILL TOO EARLY TO DETERMINE THE OVERALL SEVERE WEATHER THREAT WITH THIS FRONT AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY OR TONIGHT. .EMERGENCY MANAGEMENT COORDINATION... NO CALL IS SCHEDULED. RIECK
The La Crosse radar (KARX), 146 km away, was scanning. The volume nearest the first event began at 09:40 UTC.
2 hail. Local standard time, as filed.
Fire Department Rescue Squad measured hail of one and one half inches in diameter.
The General Public reported the size of hail of three fourths of an inch in diameter.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2007Every state in 2007This day in weather historyWarnings in Iowa, August 2007
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: 50307, 50309.