Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 95, NWS La Crosse, WI

August 27, 2021Mitchell County, Iowa

NWS La Crosse, WI issued this severe thunderstorm warning at Aug 27, 2021, 8:09 PM CDT for Mitchell County, Iowa. It was in force for 25 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 27, 2021, 8:09 PM CDT (01:09 UTC)
Expired
Aug 27, 2021, 8:34 PM CDT
In force
25 min
Issued by
NWS La Crosse, WI
Area
Storm-based polygon
Hail
1.0 in
Wind
60.0 mph

County Mitchell County, IA

The radar

The La Crosse radar (KARX), 148 km from the middle of the area, began a volume at 01:08 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.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Aug 27, 5:15 PM CDTTornado WatchSPC6 hr

The nearest sounding before it

Minneapolis, MN (KMPX), launched 00:00Z, 1.2 hours before the alert went out and 177 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.

Skew-T log-pSkew-T log-p diagram, Minneapolis, MN at 00:00Z on 2021-08-28Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 652 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Minneapolis, MN at 00:00Z on 2021-08-28The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 140 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
652 J/kg
Mixed-layer CIN
-66 J/kg
Mixed-layer LCL
643 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
140 m²/s²
0-3 km storm-relative helicity
175 m²/s²
Significant tornado parameter
0.5
Supercell composite
3.5

Open this sounding in Storm Lab

The text

As transmitted.

069 
WUUS53 KARX 280109
SVRARX
IAC131-280200-
/O.NEW.KARX.SV.W.0095.210828T0109Z-210828T0200Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service La Crosse WI
809 PM CDT Fri Aug 27 2021

The National Weather Service in La Crosse has issued a

* Severe Thunderstorm Warning for...
  Western Mitchell County in north central Iowa...

* Until 900 PM CDT.

* At 809 PM CDT, a severe thunderstorm was located 7 miles east of
  Manly, or 11 miles northeast of Mason City, moving northeast at 35
  mph.

  HAZARD...60 mph wind gusts and quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* Locations impacted include...
  Osage, St. Ansgar, Stacyville, and Mitchell.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 1100 PM CDT for north central
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 4339 9302 4348 9288 4342 9272 4330 9266
      4321 9299 4321 9302
TIME...MOT...LOC 0109Z 235DEG 31KT 4327 9305 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Skow
1 follow-up statement
198 
WWUS53 KARX 280134
SVSARX

Severe Weather Statement
National Weather Service La Crosse WI
834 PM CDT Fri Aug 27 2021

IAC131-280144-
/O.CAN.KARX.SV.W.0095.000000T0000Z-210828T0200Z/
Mitchell IA-
834 PM CDT Fri Aug 27 2021

...THE SEVERE THUNDERSTORM WARNING FOR WESTERN MITCHELL COUNTY IS
CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning has been cancelled.  However heavy rain is
still possible with this thunderstorm.

LAT...LON 4339 9302 4348 9288 4342 9272 4330 9266
      4321 9299 4321 9302
TIME...MOT...LOC 0133Z 235DEG 31KT 4340 9280 

$$

Skow

The office that day

Everything else NWS La Crosse, WI issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 27, 7:04 PM CDTAreal Flood AdvisoryARXChickasaw, Howard116 min
Aug 27, 7:29 PM CDTSevere Thunderstorm WarningARXAllamakee, Clayton, Winneshiek46 min
Aug 27, 7:38 PM CDTFlash Flood WatchARXAllamakee, Chickasaw, Clayton, Fayette, Floyd, Howard and 2 more18 hr
Aug 27, 8:03 PM CDTSevere Thunderstorm WarningARXClayton42 min
Aug 27, 8:45 PM CDTFlash Flood WarningARXHoward, Mitchell9 hr
Aug 27, 10:26 PM CDTSpecial Weather StatementARXChickasaw, Howard, Winneshiek34 min
Aug 27, 11:07 PM CDTSpecial Weather StatementARXWinneshiek23 min
Aug 27, 11:12 PM CDTFlash Flood WarningARXChickasaw, Floyd6 hr
Aug 28, 1:16 AM CDTFlash Flood WarningARXFayette, Winneshiek4 hr
Aug 28, 3:00 AM CDTSpecial Weather StatementARXClayton30 min
Aug 28, 3:06 AM CDTRiver Flood WarningARXClayton3 days
Aug 28, 3:06 AM CDTRiver Flood WarningARXClayton3 days
Aug 28, 4:05 AM CDTRiver Flood WarningARXFloyd70 hr
Aug 28, 9:39 AM CDTAreal Flood WarningARXChickasaw, Fayette, Floyd, Howard, Mitchell, Winneshiek30 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.