Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 108, NWS La Crosse, WI

December 15, 20214 counties in Iowa

NWS La Crosse, WI issued this severe thunderstorm warning at Dec 15, 2021, 7:29 PM CST for 4 counties in Iowa. It was in force for 61 min. 4 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, 7:29 PM CST (01:29 UTC)
Expired: Dec 15, 2021, 8:30 PM CST
In force: 61 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, Fayette County, IA, Winneshiek County, IA

The radar

The La Crosse radar (KARX), 105 km from the middle of the area, began a volume at 01:27 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, 8:13 PM CST	TSTM WND DMG	Stanley, IA	TREE REPORTED DOWN IN STANLEY. TIME ESTIMATED FROM RADAR.
Dec 15, 8:23 PM CST	TSTM WND DMG	Waukon, IA	TREE DOWN. TIME ESTIMATED FROM RADAR.
Dec 15, 8:25 PM CST	TSTM WND DMG	4 Nne Bluffton, IA	MULTIPLE TREES DOWN.
Dec 15, 8:30 PM CST	TSTM WND GST 50	Littleport, IA

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, 1.5 hours before the alert went out and 184 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.

406 
WUUS53 KARX 160129
SVRARX
IAC005-043-065-191-160230-
/O.NEW.KARX.SV.W.0108.211216T0129Z-211216T0230Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service La Crosse WI
729 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...
  Fayette County in northeastern Iowa...
  Allamakee County in northeastern Iowa...
  Winneshiek County in northeastern Iowa...

* Until 830 PM CST.

* At 729 PM CST, severe thunderstorms were located along a line
  extending from Lime Springs to near Protivin to near Tripoli,
  moving northeast at 70 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...
  Spillville and Ridgeway around 740 PM CST.
  Hawkeye and Waucoma around 745 PM CST.
  Decorah and West Union around 750 PM CST.
  
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

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

&&

LAT...LON 4264 9208 4350 9208 4350 9133 4264 9131
TIME...MOT...LOC 0129Z 239DEG 58KT 4346 9226 4320 9216 4284 9223 

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

2 follow-up statements

492 
WWUS53 KARX 160146
SVSARX

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

IAC005-043-065-191-160230-
/O.CON.KARX.SV.W.0108.000000T0000Z-211216T0230Z/
Clayton IA-Fayette IA-Allamakee IA-Winneshiek IA-
746 PM CST Wed Dec 15 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 830 PM CST
FOR WESTERN CLAYTON...FAYETTE...ALLAMAKEE AND WINNESHIEK COUNTIES...

At 746 PM CST, severe thunderstorms were located along a line
extending from near Harmony to near Decorah to 6 miles south of
Sumner, moving east at 50 mph.

HAZARD...70 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
  Decorah, Oelwein, Fayette, Arlington, Volga, Elkader and 
  Farmersburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 4264 9208 4350 9208 4350 9133 4264 9131
TIME...MOT...LOC 0146Z 257DEG 45KT 4360 9198 4334 9188 4275 9208 

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

710 
WWUS53 KARX 160210
SVSARX

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

IAC005-043-065-191-160230-
/O.CON.KARX.SV.W.0108.000000T0000Z-211216T0230Z/
Clayton IA-Fayette IA-Allamakee IA-Winneshiek IA-
810 PM CST Wed Dec 15 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 830 PM CST
FOR WESTERN CLAYTON...FAYETTE...ALLAMAKEE AND WINNESHIEK COUNTIES...

At 810 PM CST, severe thunderstorms were located along a line
extending from near Spring Grove to 6 miles northeast of Ossian to
near Stanley, moving east at 35 mph.

HAZARD...70 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Decorah, Oelwein, Waukon, West Union, Elkader, Postville, Monona,
Fayette, Strawberry Point, Fairbank, Calmar, Edgewood, Ossian, Elgin,
Clermont, Maynard, Hawkeye, Arlington, Spillville and Fort Atkinson.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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

&&

LAT...LON 4264 9208 4350 9208 4350 9133 4264 9131
TIME...MOT...LOC 0210Z 253DEG 33KT 4351 9159 4319 9165 4262 9186 

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

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, 7:38 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
Dec 15, 8:29 PM CST	Severe Thunderstorm Warning Considerable damage threat	ARX	Allamakee, Clayton	31 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.