Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 112, NWS La Crosse, WI

December 15, 2021Allamakee County, Clayton County, Iowa

NWS La Crosse, WI issued this severe thunderstorm warning at Dec 15, 2021, 8:29 PM CST for Allamakee County, Clayton County, Iowa. It was in force for 31 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: Dec 15, 2021, 8:29 PM CST (02:29 UTC)
Expired: Dec 15, 2021, 9:00 PM CST
In force: 31 min
Issued by: NWS La Crosse, WI
Area: Storm-based polygon
Tornado: Possible
Damage threat: Considerable
Hail: 0.75 in
Wind: 70.0 mph

Counties Allamakee County, IA, Clayton County, IA

The radar

The La Crosse radar (KARX), 89 km from the middle of the area, began a volume at 02:33 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
Dec 15, 8:30 PM CST	TSTM WND GST 50	Littleport, IA
Dec 15, 8:41 PM CST	TSTM WND GST 48	Strawberry Point, IA	SUSTAINED WINDS.

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
Dec 15, 5:30 PM CST	Tornado Watch	SPC	6 hr

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 2.5 hours before the alert went out and 180 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: 229 J/kg
Mixed-layer CIN: -358 J/kg
Mixed-layer LCL: 1061 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: 433 m²/s²
0-3 km storm-relative helicity: 496 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

943 
WUUS53 KARX 160229
SVRARX
IAC005-043-160300-
/O.NEW.KARX.SV.W.0112.211216T0229Z-211216T0300Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service La Crosse WI
829 PM CST Wed Dec 15 2021

The National Weather Service in La Crosse has issued a

* Severe Thunderstorm Warning for...
  Western Clayton County in northeastern Iowa...
  Allamakee County in northeastern Iowa...

* Until 900 PM CST.

* At 829 PM CST, severe thunderstorms were located along a line
  extending from New Albin to near Postville to Strawberry Point,
  moving northeast at 65 mph.

  HAZARD...70 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect considerable tree damage. Damage is likely to 
           mobile homes, roofs, and outbuildings.

* Severe thunderstorms will be near...
  Elkader around 840 PM CST.

Other locations impacted by these severe thunderstorms include
Hanover, Volney, County Roads A 52 And W 60, State Road 76 And County
X 16, Mederville, Elon and Quandahl.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 1100 PM CST for northeastern
Iowa.

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


&&

LAT...LON 4304 9160 4350 9161 4350 9133 4264 9130
      4264 9160
TIME...MOT...LOC 0229Z 238DEG 58KT 4351 9132 4310 9148 4268 9154 

TORNADO...POSSIBLE
THUNDERSTORM DAMAGE THREAT...CONSIDERABLE
HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...70 MPH

$$

Rieck

1 follow-up statement

473 
WWUS53 KARX 160255
SVSARX

Severe Weather Statement
National Weather Service La Crosse WI
855 PM CST Wed Dec 15 2021

IAC005-043-160305-
/O.EXP.KARX.SV.W.0112.000000T0000Z-211216T0300Z/
Clayton IA-Allamakee IA-
855 PM CST Wed Dec 15 2021

...THE SEVERE THUNDERSTORM WARNING FOR WESTERN CLAYTON AND ALLAMAKEE
COUNTIES WILL EXPIRE AT 900 PM CST...
    
The storms which prompted the warning have moved out of the area.
Therefore, the warning will be allowed to expire.

A Tornado Watch remains in effect until 1100 PM CST for northeastern
Iowa.

LAT...LON 4304 9160 4350 9161 4350 9133 4264 9130
      4264 9160
TIME...MOT...LOC 0255Z 238DEG 58KT 4372 9086 4331 9102 4289 9109 

$$

Rieck

The office that day

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

Issued	Product	Office	Counties	Lasted
Dec 15, 6:37 PM CST	Severe Thunderstorm Warning Considerable damage threat	ARX	Chickasaw, Floyd, Howard, Mitchell	68 min
Dec 15, 6:44 PM CST	Tornado Warning	ARX	Floyd	32 min
Dec 15, 7:25 PM CST	Tornado Warning	ARX	Howard	20 min
Dec 15, 7:29 PM CST	Severe Thunderstorm Warning Considerable damage threat	ARX	Allamakee, Clayton, Fayette, Winneshiek	61 min
Dec 15, 7:38 PM CST	Tornado Warning	ARX	Winneshiek	37 min
Dec 15, 8:16 PM CST	Severe Thunderstorm Warning Considerable damage threat	ARX	Allamakee, Clayton	74 min

Nearby

Severe Thunderstorm Warnings in Iowa, 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.