Thunderstorms with high winds and extremely heavy rain moved across northeast Iowa during the evening of September 21st into the early morning of the 22nd. Winds of 60 to 70 mph occurred near Rockford (Floyd County) and Nora Springs (Floyd County).
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 with high winds and extremely heavy rain moved across northeast Iowa during the evening of September 21st into the early morning of the 22nd. Winds of 60 to 70 mph occurred near Rockford (Floyd County) and Nora Springs (Floyd County). A small tornado touched down west of Nashua (Floyd County) and produced some crop damage. Flash flooding caused water to cover most roads over the southern two-thirds of Floyd County along with the southern sections of Chickasaw County and mudslides occurred across Allamakee County. The Governor of Iowa signed a disaster proclamation because of all the flooding in September for Allamakee, Chickasaw, Clayton, Fayette, Floyd, Howard, Mitchell and Winneshiek Counties and a federal disaster declaration was made for the same counties.
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 Sep 21, 5:50 AM CST, 40 minutes earlier.
Area Forecast Discussion
National Weather Service La Crosse WI
650 AM CDT Wed Sep 21 2016
.SHORT TERM...(Today and tonight)
Issued at 400 AM CDT Wed Sep 21 2016
For early this morning, the combination of moderate to strong
isentropic lift and 850 mb moisture transport will result in the
continual development of showers and storms along the Mississippi
River. With precipitable water values climbing to around 1.7
inches and warm cloud layer depths of 3.5 to 4 km, these storms
will capable of producing very heavy rain. In addition with steep
mid-level lapse rates will have to watch for an isolated threat
for damaging winds and large hail. As the morning progresses, the
moisture transport will slowly slide east and any additional
development will likely occur along the western periphery of the
cold pool across southwest and central Wisconsin.
For early this afternoon, it looks like an 850 to 700 mb cap
will limit the convection across much of southeast Minnesota,
northeast Iowa, and near the Mississippi River in western
Wisconsin. Meanwhile additional thunderstorm development looks likely
along the warm front across north-central and southwest
Wisconsin. The CAM models look to be handling this well, so
trended the forecast toward them, so some better timing could be
included into the forecast.
For late this afternoon into tonight, another short wave trough
will move through the area. As the ascent increases ahead of this
short wave, the 850 to 700 mb cap will gradually erode across
central and southwest Minnesota. With the 0-1 km mixed layer
CAPES between 2.5 and 3.5K J/kg ahead of this front, storms will
quickly develop ahead of this wave. It looks initially that there
will be the potential for supercells to develop. The main threat
with these storms will be large hail and isolated tornadoes. This
convection will then evolve into a line which will be capable of
producing damaging winds. Due to this, the Storm Prediction Center
has southern Minnesota, west-central and southwest Wisconsin, and
northern Iowa under a slight risk of severe storms.
The combination of moisture from Gulf of Mexico and Hurricane
Paine will result in the precipitable water values climbing to
around 2 inches. This is near records for this time of year. In
addition the warm cloud depths will be in the 3.5 to 4 km range.
This will result in rather efficient rain-producing showers and
storms. Additional rainfall amounts will be in the 1 to 4 inch
range. This could result in some flash flooding. A few location may
see a 2-day rainfall total in the excess of 7 inches by Thursday
afternoon.
.LONG TERM...(Thursday through Tuesday)
Issued at 400 AM CDT Wed Sep 21 2016
On Thursday, the moisture transport starts to shift east of the
area. As this occurs, the better forcing will be moving away from
us and the showers and storms will become more scattered. With
precipitable water values still in the 1.5 to 2 inch range and
warm cloud depths of 3.5 to 4 km, the storms will be capable of
producing some heavy rain.
On Friday and Friday night, the warm front will move north across
the area. As this occurs, the chances of rain will be on the
decrease.
The next round of heavy rain looks to be on Saturday night and
Sunday as a cold front moves east through the area. This front
looks to be progressive, so the threat for additional flooding
looks minimal.
&&
.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 650 AM CDT Wed Sep 21 2016
Broad area of showers and storms along and east of the MS River
expected to slowly drift eastward this morning, mainly impacting
KLSE. Expect periodic reductions in visibility/cloud bases into
the MVFR (possibly IFR) range with stronger storms. Should see a
break in convective activity late this morning and afternoon
before the next round of thunderstorms this evening and overnight.
Widespread heavy rainfall likely to drop conditions at both
KLSE/KRST into the IFR range, but given timing/coverage
uncertainties at this time, will broad brush potential with
prolonged MVFR conditions. Non-thunderstorm winds will continue
from the southeast, generally 10 kts or less.
&&
.HYDROLOGY...Today through Thursday
Issued at 400 AM CDT Wed Sep 21 2016
It continues to look like there will be a potential for a serious
flooding situation from today through Thursday. The first round of
this morning is mainly preconditioning the soils which will make
it easier for flash flooding to occur with the second round of
very heavy rain which is expected to move into the area from late
this afternoon into tonight. It looks like there will be a
potential for another 1 to 4 inches of rain with this round.
Localized rainfall amounts from Tuesday night through Thursday may
be in the excess of 7 inches.
Stay weather aware and be ready to move to higher ground! Several
rivers could go into flood. Minor to major river flooding is
possible.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Flash Flood Watch through Thursday evening for WIZ017-029-
032>034-041>044-053>055-061.
MN...Flash Flood Watch through Thursday evening for MNZ079-086>088-
094>096.
IA...Flash Flood Watch through Thursday evening for IAZ008>011-018-
019-029-030.
&&
SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...ROGERS
HYDROLOGY...BOYNEHAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE LA CROSSE WI 447 AM CDT WED SEP 21 2016 IAZ008>011-018-019-029-030-MNZ079-086>088-094>096-WIZ017-029- 032>034-041>044-053>055-061-221100- MITCHELL-HOWARD-WINNESHIEK-ALLAMAKEE-FLOYD-CHICKASAW-FAYETTE- CLAYTON-WABASHA-DODGE-OLMSTED-WINONA-MOWER-FILLMORE-HOUSTON- TAYLOR-CLARK-BUFFALO-TREMPEALEAU-JACKSON-LA CROSSE-MONROE-JUNEAU- ADAMS-VERNON-CRAWFORD-RICHLAND-GRANT- 447 AM CDT WED SEP 21 2016 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHEAST IOWA...SOUTHEAST MINNESOTA...AND FROM SOUTHWEST INTO CENTRAL WISCONSIN. .DAY ONE...TODAY AND TONIGHT A FLASH FLOOD WATCH IN EFFECT. PERIODIC THUNDERSTORMS WILL CONTINUE THROUGH TONIGHT. THE MAIN THREAT FROM THESE STORMS WILL BE HEAVY RAIN WHICH MAY RESULT IN RIVER AND FLASH FLOODING. IN ADDITION...THERE WILL BE A THREAT FOR DAMAGING WINDS AND LARGE HAIL THIS AFTERNOON AND EVENING. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY STORMS CAPABLE OF PRODUCING FLASH FLOODING AND RIVER FLOODING WILL CONTINUE THROUGH THURSDAY EVENING. DUE TO THIS...A FLASH FLOOD WATCH WILL REMAIN IN EFFECT FOR THIS TIME PERIOD. PERIODIC STORMS WILL BE POSSIBLE FROM THURSDAY THROUGH TUESDAY. AT THIS TIME...THE MAIN THREAT FROM THESE STORMS WILL BE LIGHTNING. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED AT TIMES TONIGHT THROUGH THURSDAY...WITH RAINFALL OR FLOODING REPORTS GREATLY APPRECIATED. .EMERGENCY MANAGEMENT COORDINATION... NO WEBINAR IS SCHEDULED. BOYNE
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
355 AM CDT WED SEP 21 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0355 AM HEAVY RAIN 1 NNE LANESBORO 43.74N 91.97W
09/21/2016 M1.50 INCH FILLMORE MN PUBLIC
.
&&
DBPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
535 AM CDT WED SEP 21 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0525 AM FLASH FLOOD 5 ENE PICKWICK 44.01N 91.51W
09/21/2016 WINONA MN LAW ENFORCEMENT
MUDSLIDE AT MILE MARKER 20 OF SOUTHBOUND
HIGHWAY 61. TREES DOWN.
&&
CJAPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
700 AM CDT WED SEP 21 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0657 AM HEAVY RAIN 1 S DE SOTO 43.41N 91.19W
09/21/2016 M2.92 INCH CRAWFORD WI CO-OP OBSERVER
. THE DURATION OF THE HEAVY RAIN EVENT WAS
24 HOURS.
&&
CJAPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
705 AM CDT WED SEP 21 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0704 AM FLASH FLOOD 3 ENE PICKWICK 44.00N 91.56W
09/21/2016 WINONA MN LAW ENFORCEMENT
WATER OVER PRIVATE DRIVEWAYS.
&&
CJAPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
713 AM CDT WED SEP 21 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0711 AM HEAVY RAIN 3 S WINONA 44.00N 91.66W
09/21/2016 M2.38 INCH WINONA MN LAW ENFORCEMENT
.
&&
CJAPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LA CROSSE WI
715 AM CDT WED SEP 21 2016
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0710 AM FLASH FLOOD DE SOTO 43.42N 91.20W
09/21/2016 CRAWFORD WI CO-OP OBSERVER
MUDSLIDE COVERING ONE LANE OF HIGHWAY 82.
&&
CJAThe La Crosse radar (KARX), 37 km away, was scanning. The volume nearest the first event began at 12:29 UTC.
10 heavy rain, 10 flood, 9 thunderstorm wind, 8 flash flood, 1 hail, 1 tornado. Local standard time, as filed.
At least two mudslides occurred along State Highway 26 between New Albin and Lansing.
Near Nora Springs, 9.36 inches of rain fell.
The COOP observer in Charles City measured 6.35 inches of rain.
A wind gust of 66 mph was measured south of Nora Springs.
The automated weather observing equipment at the Charles City airport measured 4.79 inches of rain.
A tree was blown down onto a house in Nora Springs.
Near Ionia, 6.38 inches of rain fell.
Trees were blown down in Nora Springs.
Ping pong ball sized hail fell in Rockford.
Trees were blown down west of Rockford.
In New Hampton, 3.59 inches of rain fell.
In St. Ansgar, 3.00 inches of rain fell.
An estimated wind gust of 70 mph occurred west of Marble Rock.
West of Nashua, 7.55 inches of rain fell.
Trees, two to three foot in diameter, were blown down just southeast of Marble Rock.
Near Riceville, 4.54 inches of rain fell.
Machine sheds were blown down and destroyed southeast of Marble Rock.
A weak tornado touched down west of Nashua. The tornado moved through rural areas producing only some crop damage.
In Waucoma, 3.91 inches of rain fell.
Heavy rain caused water to go over several roads in the southwest two-thirds of Floyd County. The roads were impassable making travel not possible. Water was reported to still be rising southwest of Charles City after sunrise on the 22nd.
The COOP observer near Dorchester measured 4.21 inches of rain.
A wind gust of 60 mph occurred just west of Marble Rock.
A wind gust of 70 mph occurred just east of Marble Rock.
Flood waters covered several rural roads in the western sections of Mitchell County.
Heavy rain caused flooding to occur in the Bluffton area along the Upper Iowa River and Pine and Silver Creeks. Street flooding occurred in Decorah.
Runoff from heavy rain caused 4 to 5 mudslides to occur across Allamakee County. Mudslides north of Lansing sent downed trees on to some roads. Flooding in the Yellow River State Forest prompted officials to close all the campgrounds.
Runoff from heavy rains caused water to cover the roads in Carpenter. Water was also over roads near Stacyville.
Runoff from heavy rain pushed the Upper Iowa River out of its banks near Dorchester. The river crested over three feet above the flood stage at 17.19 feet.
Flood waters from Crane Creek covered U.S. Highway 18 northeast of Hawkeye and the streets were flooded in Hawkeye. Numerous roads between West Union and Sumner had water over them.
Runoff from heavy rain pushed the Turkey River out of its banks near Eldorado. The river crested over four feet above the flood stage at 17.12 feet.
The fire department had to pump water out of basements in Nashua and volunteers helped sandbag homes in both Nashua and Ionia. Flood waters from the Wapsipinicon River covered U.S. Highway 18 west of New Hampton. For the second time this month, school was canceled in the New Hampton school district because of flooding.
Roads west of Cresco had water over them because of runoff from heavy rain. Water also covered roads around Vernon Springs.
Runoff from heavy rain pushed the Turkey River out of its banks in Spillville. The river crested almost five above the flood stage at 13.73 feet.
Runoff from heavy rain pushed the Turkey River out of its banks in Clermont. The river crested a foot and a half above the flood stage at 17.66 feet.
Sections of County Highway B45 were washed out near Monona. Sandbagging occurred in Farmersburg to protect the community from flood waters on Howard Creek.
Runoff from heavy rain pushed the Turkey River out of its banks in Elkader. The river crested over eight feet above the flood stage at 20.65 feet.
Runoff from heavy rain pushed the Cedar River out of its banks in Charles City. The river crested nine feet above the flood stage at 21 feet.
Runoff from heavy rain pushed the Cedar River out of its banks near Osage. The river crested almost six feet above the flood stage at 27.78 feet.
Runoff from heavy rain pushed the Turkey River out of its banks in Garber. The river crested over eight feet above the flood stage at 25.15 feet.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Iowa in 2016Every state in 2016This day in weather historyThe tornado archive for Iowa, 2016Warnings in Iowa, September 2016
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: 658559, 659833, 659838, 658890, 659251, 658892, 659221, 659097, 659098, 659096, 659241, 659227, 659099, 659108, 659101, 659835, 659103, 659100, 659248, 659104, 659839, 659105, 659106, 660607, 659113, 659754, 659201, 660500, 659202, 660514, 659203, 659226, 660511, 660524, 659246, 660530, 660498, 660452, 660532.