Alert archive / Minnesota / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 100, NWS La Crosse, WI

September 20, 20214 counties in Minnesota

NWS La Crosse, WI issued this severe thunderstorm warning at Sep 20, 2021, 3:47 PM CDT for 4 counties in Minnesota. It was in force for 43 min. 9 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, 3:47 PM CDT (20:47 UTC)
Expired: Sep 20, 2021, 4:30 PM CDT
In force: 43 min
Issued by: NWS La Crosse, WI
Area: Storm-based polygon
Tornado: Possible
Hail: 0.75 in
Wind: 60.0 mph

Counties Dodge County, MN, Fillmore County, MN, Mower County, MN, Olmsted County, MN

The radar

The La Crosse radar (KARX), 121 km from the middle of the area, began a volume at 20:51 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, 3:55 PM CDT	TSTM WND GST 41	3 E Austin, MN	AWOS STATION KAUM AUSTIN MUNICIPAL AIRPORT.
Sep 20, 4:20 PM CDT	TSTM WND GST 35	1 Ene Dexter, MN	MESONET STATION MN010 1 ENE DEXTER.
Sep 20, 4:20 PM CDT	HAIL 0.25	2 Ne Rochester, MN	HAILED FOR 2 MINUTES
Sep 20, 4:20 PM CDT	HAIL 0.25	2 Ne Rochester, MN	HAILED FOR 2 MINUTES.
Sep 20, 4:24 PM CDT	TSTM WND GST 46	3 Nnw Stewartville, MN	ASOS STATION KRST ROCHESTER INTERNATIONAL AIRPORT.
Sep 20, 4:25 PM CDT	HAIL 0.25	1 Nnw Rochester, MN
Sep 20, 4:25 PM CDT	HAIL 0.88	1 Ssw Rochester, MN	DIME TO NICKEL HAIL REPORTED.
Sep 20, 4:30 PM CDT	TSTM WND GST 45	3 N Stewartville, MN	MESONET STATION MN070 3 N STEWARTVILLE.
Sep 20, 4:35 PM CDT	TSTM WND GST 41	Rochester, MN	AWOS STATION K9MN MAYO HELIPAD.

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
Sep 20, 2:07 PM CDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 8.8 hours before the alert went out and 135 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: 148 J/kg
Mixed-layer CIN: -141 J/kg
Mixed-layer LCL: 1002 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 210 m²/s²
0-3 km storm-relative helicity: 162 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.4

Open this sounding in Storm Lab

The text

As transmitted.

710 
WUUS53 KARX 202047
SVRARX
MNC039-045-099-109-202130-
/O.NEW.KARX.SV.W.0100.210920T2047Z-210920T2130Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service La Crosse WI
347 PM CDT Mon Sep 20 2021

The National Weather Service in La Crosse has issued a

* Severe Thunderstorm Warning for...
  Western Olmsted County in southeastern Minnesota...
  Northern Mower County in southeastern Minnesota...
  Southeastern Dodge County in southeastern Minnesota...
  Northwestern Fillmore County in southeastern Minnesota...

* Until 430 PM CDT.

* At 346 PM CDT, a severe thunderstorm was located over Brownsdale,
  or 8 miles northeast of Austin, moving northeast at 45 mph.

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

  SOURCE...Radar indicated.

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

* This severe thunderstorm will be near...
  Hayfield around 355 PM CDT.
  Stewartville around 415 PM CDT.
  Rochester around 420 PM CDT.

This includes Interstate 90 in Minnesota between mile markers 180 and
182, and between mile markers 194 and 222.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4366 9294 4381 9304 4417 9242 4382 9218
TIME...MOT...LOC 2046Z 237DEG 41KT 4378 9289 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Skow

2 follow-up statements

477 
WWUS53 KARX 202058
SVSARX

Severe Weather Statement
National Weather Service La Crosse WI
358 PM CDT Mon Sep 20 2021

MNC039-045-099-109-202130-
/O.CON.KARX.SV.W.0100.000000T0000Z-210920T2130Z/
Olmsted MN-Mower MN-Dodge MN-Fillmore MN-
358 PM CDT Mon Sep 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 430 PM CDT
FOR WESTERN OLMSTED...NORTHEASTERN MOWER...SOUTHEASTERN DODGE AND
NORTHWESTERN FILLMORE COUNTIES...

At 357 PM CDT, a severe thunderstorm was located near Hayfield, or 13
miles southeast of Dodge Center, moving northeast at 45 mph.

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

SOURCE...Radar indicated.

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

This severe storm will be near...
  Stewartville around 410 PM CDT.
  Rochester around 420 PM CDT.

Other locations impacted by this severe thunderstorm include Salem 
Corners, Rock Dell, Rochester Airport, Waltham and Renova.

This includes Interstate 90 in Minnesota near mile marker 182, and
between mile markers 194 and 222.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4367 9291 4380 9289 4386 9293 4417 9242
      4382 9218
TIME...MOT...LOC 2057Z 237DEG 41KT 4385 9274 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Skow

720 
WWUS53 KARX 202110
SVSARX

Severe Weather Statement
National Weather Service La Crosse WI
410 PM CDT Mon Sep 20 2021

MNC039-045-099-109-202130-
/O.CON.KARX.SV.W.0100.000000T0000Z-210920T2130Z/
Olmsted MN-Mower MN-Dodge MN-Fillmore MN-
410 PM CDT Mon Sep 20 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 430 PM CDT
FOR WESTERN OLMSTED...NORTHEASTERN MOWER...SOUTHEASTERN DODGE AND
NORTHWESTERN FILLMORE COUNTIES...

At 409 PM CDT, a severe thunderstorm was located near Stewartville,
or 7 miles southwest of Rochester, moving northeast at 45 mph.

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

SOURCE...Radar indicated. Winds up to 40 to 45 mph have been 
         observed with these storms.

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

This severe storm will be near...
  Rochester around 415 PM CDT.

This includes Interstate 90 in Minnesota between mile markers 197 and
222.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4373 9274 4385 9276 4394 9279 4417 9242
      4382 9218
TIME...MOT...LOC 2109Z 237DEG 41KT 4393 9257 

TORNADO...POSSIBLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...0.75 IN
WIND THREAT...OBSERVED
MAX WIND GUST...60 MPH

$$

Skow

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 20, 3:23 PM CDT	Special Weather Statement	ARX	Mower	37 min
Sep 20, 4:30 PM CDT	Severe Thunderstorm Warning	ARX	Fillmore, Mower, Olmsted, Wabasha, Winona	45 min
Sep 20, 5:03 PM CDT	Tornado Warning	ARX	Fillmore	27 min
Sep 20, 5:12 PM CDT	Special Weather Statement	ARX	Winona	33 min
Sep 20, 5:38 PM CDT	Special Weather Statement	ARX	Houston	37 min

Nearby

Severe Thunderstorm Warnings in Minnesota, 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.