Alert archive / Iowa / Severe Thunderstorm Warnings in 2021
Severe Thunderstorm Warning 93, NWS La Crosse, WI
NWS La Crosse, WI issued this severe thunderstorm warning at Aug 27, 2021, 7:29 PM CDT for Allamakee County, Clayton County, Winneshiek County, Iowa. It was in force for 46 min. 2 reports came from inside the area while it was in force.
The area
The outline as issued, with what was reported inside it.
The facts
- Issued
- Aug 27, 2021, 7:29 PM CDT (00:29 UTC)
- Expired
- Aug 27, 2021, 8:15 PM CDT
- In force
- 46 min
- Issued by
- NWS La Crosse, WI
- Area
- Storm-based polygon
- Hail
- 0.75 in
- Wind
- 60.0 mph
Counties Allamakee County, IA, Clayton County, IA, Winneshiek County, IA
The radar
The La Crosse radar (KARX), 86 km from the middle of the area, began a volume at 00:33 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
What was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Aug 27, 7:42 PM CDT | TSTM WND DMG | Postville, IA | POWER LINES DOWN. |
| Aug 27, 8:07 PM CDT | TSTM WND DMG | Monona, IA | REPORT OF POWERLINES DOWN. |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The watch it was issued in
The SPC watch in force over the same counties when this warning went out.
| Issued | Product | Office | Lasted |
|---|---|---|---|
| Aug 27, 5:15 PM CDT | Tornado Watch | SPC | 6 hr |
The nearest sounding before it
Davenport, (KDVN), launched 00:00Z, 0.5 hours before the alert went out and 182 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 995 J/kg
- Mixed-layer CIN
- -68 J/kg
- Mixed-layer LCL
- 1707 m above ground
- 0-6 km bulk shear
- 26 kt
- 0-1 km storm-relative helicity
- 53 m²/s²
- 0-3 km storm-relative helicity
- 148 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.3
The text
As transmitted.
695
WUUS53 KARX 280029
SVRARX
IAC005-043-191-280115-
/O.NEW.KARX.SV.W.0093.210828T0029Z-210828T0115Z/
BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service La Crosse WI
729 PM CDT Fri Aug 27 2021
The National Weather Service in La Crosse has issued a
* Severe Thunderstorm Warning for...
Northwestern Clayton County in northeastern Iowa...
Southern Allamakee County in northeastern Iowa...
Southeastern Winneshiek County in northeastern Iowa...
* Until 815 PM CDT.
* At 729 PM CDT, a severe thunderstorm was located near Postville, or
10 miles southwest of Waukon, moving southeast at 40 mph.
HAZARD...60 mph wind gusts and penny size hail.
SOURCE...Radar indicated.
IMPACT...Expect damage to roofs, siding, and trees.
* Locations impacted include...
Postville, Monona, McGregor, Marquette, Farmersburg, Hardin, Luana,
Castalia, and Waterville.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A Tornado Watch remains in effect until 1100 PM CDT for northeastern
Iowa...and southwestern Wisconsin.
For your protection move to an interior room on the lowest floor of a
building.
Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4305 9161 4308 9161 4308 9170 4310 9175
4326 9167 4319 9117 4307 9118 4289 9117
TIME...MOT...LOC 0029Z 299DEG 33KT 4315 9161
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH
$$
Skow3 follow-up statements
727
WWUS53 KARX 280044
SVSARX
Severe Weather Statement
National Weather Service La Crosse WI
744 PM CDT Fri Aug 27 2021
IAC005-043-191-280115-
/O.CON.KARX.SV.W.0093.000000T0000Z-210828T0115Z/
Clayton IA-Allamakee IA-Winneshiek IA-
744 PM CDT Fri Aug 27 2021
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM CDT
FOR NORTHWESTERN CLAYTON...SOUTHERN ALLAMAKEE AND SOUTHEASTERN
WINNESHIEK COUNTIES...
At 744 PM CDT, a severe thunderstorm was located near Monona, or 12
miles south of Waukon, moving southeast at 40 mph.
HAZARD...60 mph wind gusts and nickel size hail.
SOURCE...Trained weather spotters.
IMPACT...Expect damage to roofs, siding, and trees.
Locations impacted include...
Postville, Monona, McGregor, Marquette, Farmersburg, Hardin, Luana,
Castalia, Waterville, Volney, Spook Cave Campground, State Road 76
And County X 16, Giard, Ludlow, Watson, County Roads X 16 And W 48,
State Road 51 And County W 48, National, Effigy Mounds and Rossville.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A Tornado Watch remains in effect until 1100 PM CDT for northeastern
Iowa...and southwestern Wisconsin.
For your protection move to an interior room on the lowest floor of a
building.
Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4305 9161 4308 9161 4308 9170 4310 9175
4326 9167 4319 9117 4307 9118 4289 9117
TIME...MOT...LOC 0044Z 299DEG 33KT 4308 9144
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.88 IN
WIND THREAT...OBSERVED
MAX WIND GUST...60 MPH
$$
Skow597
WWUS53 KARX 280054
SVSARX
Severe Weather Statement
National Weather Service La Crosse WI
754 PM CDT Fri Aug 27 2021
IAC191-280103-
/O.CAN.KARX.SV.W.0093.000000T0000Z-210828T0115Z/
Winneshiek IA-
754 PM CDT Fri Aug 27 2021
...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN WINNESHIEK COUNTY
IS CANCELLED...
The severe thunderstorm which prompted the warning has moved out of
the warned area. Therefore, the warning has been cancelled.
A Tornado Watch remains in effect until 1100 PM CDT for northeastern
Iowa...and southwestern Wisconsin.
LAT...LON 4304 9158 4308 9157 4316 9145 4314 9117
4307 9118 4289 9117
TIME...MOT...LOC 0053Z 299DEG 33KT 4304 9133
$$
IAC005-043-280115-
/O.CON.KARX.SV.W.0093.000000T0000Z-210828T0115Z/
Clayton IA-Allamakee IA-
754 PM CDT Fri Aug 27 2021
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM CDT
FOR NORTHWESTERN CLAYTON AND SOUTH CENTRAL ALLAMAKEE COUNTIES...
At 753 PM CDT, a severe thunderstorm was located over Monona, or 9
miles west of Prairie Du Chien, moving southeast at 40 mph.
HAZARD...60 mph wind gusts and nickel size hail.
SOURCE...Trained weather spotters.
IMPACT...Expect damage to roofs, siding, and trees.
Locations impacted include...
Postville, Monona, McGregor, Marquette, Farmersburg, Hardin, Luana,
Froelich, and Volney.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A Tornado Watch remains in effect until 1100 PM CDT for northeastern
Iowa...and southwestern Wisconsin.
For your protection move to an interior room on the lowest floor of a
building.
Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4304 9158 4308 9157 4316 9145 4314 9117
4307 9118 4289 9117
TIME...MOT...LOC 0053Z 299DEG 33KT 4304 9133
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.88 IN
WIND THREAT...OBSERVED
MAX WIND GUST...60 MPH
$$
Skow523
WWUS53 KARX 280106
SVSARX
Severe Weather Statement
National Weather Service La Crosse WI
806 PM CDT Fri Aug 27 2021
IAC005-043-280115-
/O.CON.KARX.SV.W.0093.000000T0000Z-210828T0115Z/
Clayton IA-Allamakee IA-
806 PM CDT Fri Aug 27 2021
...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 815 PM CDT
FOR NORTH CENTRAL CLAYTON AND SOUTH CENTRAL ALLAMAKEE COUNTIES...
At 806 PM CDT, a severe thunderstorm was located near McGregor, or
near Prairie Du Chien, moving southeast at 40 mph.
HAZARD...60 mph wind gusts and nickel size hail.
SOURCE...Trained weather spotters.
IMPACT...Expect damage to roofs, siding, and trees.
Locations impacted include...
Monona, McGregor, Marquette, Farmersburg, Froelich, Spook Cave
Campground, National, Beula, Giard, Effigy Mounds, Watson and J Wood
Campground.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A Tornado Watch remains in effect until 1100 PM CDT for northeastern
Iowa.
For your protection move to an interior room on the lowest floor of a
building.
Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.
&&
LAT...LON 4297 9139 4306 9144 4313 9142 4309 9118
4307 9118 4289 9117
TIME...MOT...LOC 0106Z 299DEG 33KT 4298 9118
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.88 IN
WIND THREAT...OBSERVED
MAX WIND GUST...60 MPH
$$
SkowThe office that day
Everything else NWS La Crosse, WI issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 27, 7:04 PM CDT | Areal Flood Advisory | ARX | Chickasaw, Howard | 116 min |
| Aug 27, 7:38 PM CDT | Flash Flood Watch | ARX | Allamakee, Chickasaw, Clayton, Fayette, Floyd, Howard and 2 more | 18 hr |
| Aug 27, 8:03 PM CDT | Severe Thunderstorm Warning | ARX | Clayton | 42 min |
| Aug 27, 8:09 PM CDT | Severe Thunderstorm Warning | ARX | Mitchell | 25 min |
| Aug 27, 8:45 PM CDT | Flash Flood Warning | ARX | Howard, Mitchell | 9 hr |
| Aug 27, 10:26 PM CDT | Special Weather Statement | ARX | Chickasaw, Howard, Winneshiek | 34 min |
| Aug 27, 11:07 PM CDT | Special Weather Statement | ARX | Winneshiek | 23 min |
| Aug 27, 11:12 PM CDT | Flash Flood Warning | ARX | Chickasaw, Floyd | 6 hr |
| Aug 28, 1:16 AM CDT | Flash Flood Warning | ARX | Fayette, Winneshiek | 4 hr |
| Aug 28, 3:00 AM CDT | Special Weather Statement | ARX | Clayton | 30 min |
| Aug 28, 3:06 AM CDT | River Flood Warning | ARX | Clayton | 3 days |
| Aug 28, 3:06 AM CDT | River Flood Warning | ARX | Clayton | 3 days |
| Aug 28, 4:05 AM CDT | River Flood Warning | ARX | Floyd | 70 hr |
| Aug 28, 9:39 AM CDT | Areal Flood Warning | ARX | Chickasaw, Fayette, Floyd, Howard, Mitchell, Winneshiek | 30 hr |
Nearby
Severe Thunderstorm Warnings in Iowa, 2021Every severe thunderstorm warning in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.