Alert archive / Wisconsin / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 84, NWS Milwaukee, WI

September 20, 2021Iowa County, Sauk County, Wisconsin

NWS Milwaukee, WI issued this severe thunderstorm warning at Sep 20, 2021, 7:22 PM CDT for Iowa County, Sauk County, Wisconsin. It was in force for 38 min. 3 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: Sep 20, 2021, 7:22 PM CDT (00:22 UTC)
Expired: Sep 20, 2021, 8:00 PM CDT
In force: 38 min
Issued by: NWS Milwaukee, WI
Area: Storm-based polygon
Tornado: Possible
Hail: 0.75 in
Wind: 60.0 mph

Counties Iowa County, WI, Sauk County, WI

The radar

The La Crosse radar (KARX), 108 km from the middle of the area, began a volume at 00:20 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
Sep 20, 7:40 PM CDT	TSTM WND DMG	3 Ssw Avoca, WI	TREE DOWN BLOCKING THE ROAD AT INTERSECTION OF STATE ROAD 80 AND HICKORY GROVE ROAD.
Sep 20, 7:40 PM CDT	TSTM WND DMG	5 N Barneveld, WI	TREES DOWN ALONG COUNTY ROAD K NORTH OF BARNEVELD AND ALSO AT THE INTERSECTION OF HH AND SWEENEY.
Sep 20, 7:56 PM CDT	TSTM WND GST 49	7 Wnw Spring Green, WI	ASOS STATION KLNR LONE ROCK-AIRPORT.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 0.4 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1090 J/kg
Mixed-layer CIN: -6 J/kg
Mixed-layer LCL: 1240 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 139 m²/s²
0-3 km storm-relative helicity: 217 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 3.7

Open this sounding in Storm Lab

The text

As transmitted.

586 
WUUS53 KMKX 210022
SVRMKX
WIC049-111-210100-
/O.NEW.KMKX.SV.W.0084.210921T0022Z-210921T0100Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Milwaukee/Sullivan WI
722 PM CDT Mon Sep 20 2021

The National Weather Service in Milwaukee/Sullivan has issued a

* Severe Thunderstorm Warning for...
  Iowa County in south central Wisconsin...
  Southwestern Sauk County in south central Wisconsin...

* Until 800 PM CDT.

* At 721 PM CDT, severe thunderstorms were located along a line
  extending from near Boscobel to near Fennimore, moving east at 50
  mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Severe thunderstorms will be near...
  Dodgeville around 745 PM CDT.
  Spring Green around 755 PM CDT.

Other locations impacted by these severe thunderstorms include
Barneveld, Ridgeway, Orion, Cobb, Arena, Governor Dodge St Park,
Edmund, Clyde, Blue Mound St Park and Avoca.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4320 9043 4321 9030 4317 9020 4338 9019
      4347 8990 4321 8983 4299 8984 4292 9043
TIME...MOT...LOC 0021Z 253DEG 45KT 4315 9060 4297 9058 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

GEHRING

3 follow-up statements

994 
WWUS53 KMKX 210030
SVSMKX

Severe Weather Statement
National Weather Service Milwaukee/Sullivan WI
730 PM CDT Mon Sep 20 2021

WIC049-111-210100-
/O.CON.KMKX.SV.W.0084.000000T0000Z-210921T0100Z/
Iowa WI-Sauk WI-
730 PM CDT Mon Sep 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 800 PM CDT
FOR IOWA AND SOUTHWESTERN SAUK COUNTIES...

At 730 PM CDT, severe thunderstorms were located along a line
extending from Muscoda to 8 miles east of Fennimore, moving east at
50 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

These severe storms will be near...
  Spring Green around 800 PM CDT.

Other locations impacted by these severe thunderstorms include
Barneveld, Ridgeway, Orion, Cobb, Arena, Governor Dodge St Park,
Edmund, Clyde, Blue Mound St Park and Avoca.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4320 9043 4321 9030 4317 9020 4338 9019
      4347 8990 4321 8983 4299 8984 4292 9043
TIME...MOT...LOC 0030Z 249DEG 42KT 4318 9047 4301 9049 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

WOOD

785 
WWUS53 KMKX 210043
SVSMKX

Severe Weather Statement
National Weather Service Milwaukee/Sullivan WI
743 PM CDT Mon Sep 20 2021

WIC049-111-210100-
/O.CON.KMKX.SV.W.0084.000000T0000Z-210921T0100Z/
Iowa WI-Sauk WI-
743 PM CDT Mon Sep 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 800 PM CDT
FOR IOWA AND SOUTHWESTERN SAUK COUNTIES...

At 743 PM CDT, severe thunderstorms were located along a line
extending from 7 miles east of Muscoda to 10 miles northwest of
Dodgeville, moving east at 45 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

IMPACT...Expect damage to roofs, siding, and trees.

These severe storms will be near...
  Spring Green around 800 PM CDT.

Other locations impacted by these severe thunderstorms include
Barneveld, Ridgeway, Orion, Cobb, Arena, Governor Dodge St Park,
Edmund, Clyde, Blue Mound St Park and Avoca.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 4320 9043 4321 9030 4317 9020 4338 9019
      4347 8990 4321 8983 4299 8984 4292 9043
TIME...MOT...LOC 0043Z 249DEG 41KT 4322 9029 4305 9031 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

WOOD

800 
WWUS53 KMKX 210057
SVSMKX

Severe Weather Statement
National Weather Service Milwaukee/Sullivan WI
757 PM CDT Mon Sep 20 2021

WIC049-111-210106-
/O.EXP.KMKX.SV.W.0084.000000T0000Z-210921T0100Z/
Iowa WI-Sauk WI-
757 PM CDT Mon Sep 20 2021

...THE SEVERE THUNDERSTORM WARNING FOR IOWA AND SOUTHWESTERN SAUK
COUNTIES WILL EXPIRE AT 800 PM CDT...
            
The storms which prompted the warning have weakened below severe
limits, and no longer pose an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However gusty
winds up to 40 mph are still possible with these thunderstorms.

LAT...LON 4320 9043 4321 9030 4317 9020 4338 9019
      4347 8990 4321 8983 4299 8984 4292 9043
TIME...MOT...LOC 0056Z 253DEG 45KT 4326 9010 4309 9012 

$$

GEHRING

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 20, 7:46 PM CDT	Severe Thunderstorm Warning	MKX	Columbia, Sauk	44 min
Sep 20, 7:59 PM CDT	Special Weather Statement	MKX	Iowa	31 min
Sep 20, 8:23 PM CDT	Special Weather Statement	MKX	Marquette	37 min
Sep 20, 8:37 PM CDT	Special Weather Statement	MKX	Columbia, Sauk	38 min
Sep 20, 9:14 PM CDT	Special Weather Statement	MKX	Lafayette	46 min
Sep 20, 9:21 PM CDT	Severe Thunderstorm Warning	MKX	Columbia, Dodge	24 min
Sep 20, 9:22 PM CDT	Severe Thunderstorm Warning	MKX	Dane, Green, Iowa, Lafayette	38 min
Sep 20, 9:24 PM CDT	Tornado Warning	MKX	Dane, Green, Iowa, Lafayette	24 min
Sep 20, 9:44 PM CDT	Special Weather Statement	MKX	Green Lake	46 min
Sep 20, 10:04 PM CDT	Special Weather Statement	MKX	Green	41 min
Sep 20, 10:27 PM CDT	Special Weather Statement	MKX	Jefferson	48 min
Sep 20, 10:41 PM CDT	Severe Thunderstorm Warning	MKX	Dane, Jefferson	20 min
Sep 21, 3:04 AM CDT	Gale Watch	MKX		11 hr
Sep 21, 1:48 PM CDT	Gale Warning	MKX		50 hr
Sep 21, 1:48 PM CDT	Small Craft Advisory	MKX		17 hr
Sep 21, 1:51 PM CDT	Beach Hazards Statement	MKX	Kenosha, Milwaukee, Ozaukee, Racine, Sheboygan	58 hr

Nearby

Severe Thunderstorm Warnings in Wisconsin, 2021 Every 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.