Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 55, NWS Sioux Falls, SD

July 9, 2021Plymouth County, Sioux County, Iowa; Clay County, Union County, South Dakota

NWS Sioux Falls, SD issued this severe thunderstorm warning at Jul 9, 2021, 12:44 AM CDT for Plymouth County, Sioux County, Iowa; Clay County, Union County, South Dakota. It was in force for 46 min. 1 report 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: Jul 9, 2021, 12:44 AM CDT (05:44 UTC)
Expired: Jul 9, 2021, 1:30 AM CDT
In force: 46 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Hail: 1.0 in
Wind: 50.0 mph

Counties Plymouth County, IA, Sioux County, IA, Clay County, SD, Union County, SD

The radar

The Sioux Falls radar (KFSD), 72 km from the middle of the area, began a volume at 05:44 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
Jul 9, 12:47 AM CDT	HAIL 1	5 Sw Alcester, SD	[DELAYED REPORT] - ESTIMATES HAIL WAS QUARTER SIZE, BUT NO DAMAGE TO REPORT.

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
Jul 8, 9:33 PM CDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 5.7 hours before the alert went out and 182 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: 155 J/kg
Mixed-layer CIN: -474 J/kg
Mixed-layer LCL: 1131 m above ground
0-6 km bulk shear: 54 kt
0-1 km storm-relative helicity: 200 m²/s²
0-3 km storm-relative helicity: 406 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

The text

As transmitted.

779 
WUUS53 KFSD 090544
SVRFSD
IAC149-167-SDC027-127-090630-
/O.NEW.KFSD.SV.W.0055.210709T0544Z-210709T0630Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Sioux Falls SD
1244 AM CDT Fri Jul 9 2021

The National Weather Service in Sioux Falls has issued a

* Severe Thunderstorm Warning for...
  Southwestern Sioux County in northwestern Iowa...
  Northwestern Plymouth County in northwestern Iowa...
  East central Clay County in southeastern South Dakota...
  Northern Union County in southeastern South Dakota...

* Until 130 AM CDT.

* At 1244 AM CDT, a severe thunderstorm was located near Union Grove
  State Park, or 7 miles south of Beresford, moving east at 30 mph.

  HAZARD...Quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Damage to vehicles is expected.

* This severe thunderstorm will be near...
  Alcester around 1255 AM CDT.
  Hawarden around 110 AM CDT.
  Ireton and Craig around 125 AM CDT.

Other locations impacted by this severe thunderstorm include
Chatsworth.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4290 9683 4305 9683 4305 9629 4281 9631
TIME...MOT...LOC 0544Z 277DEG 27KT 4298 9673 

HAIL...1.00IN
WIND...<50MPH
 
$$

APT

2 follow-up statements

353 
WWUS53 KFSD 090613
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
113 AM CDT Fri Jul 9 2021

SDC027-090622-
/O.CAN.KFSD.SV.W.0055.000000T0000Z-210709T0630Z/
Clay SD-
113 AM CDT Fri Jul 9 2021

...THE SEVERE THUNDERSTORM WARNING FOR EAST CENTRAL CLAY COUNTY IS
CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

A Severe Thunderstorm Watch remains in effect until 300 AM CDT for
northwestern Iowa...and southeastern South Dakota.

LAT...LON 4287 9662 4298 9660 4301 9630 4281 9631
TIME...MOT...LOC 0612Z 275DEG 27KT 4294 9648 

$$

IAC149-167-SDC127-090630-
/O.CON.KFSD.SV.W.0055.000000T0000Z-210709T0630Z/
Sioux IA-Plymouth IA-Union SD-
113 AM CDT Fri Jul 9 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 130 AM CDT
FOR SOUTHWESTERN SIOUX...NORTHWESTERN PLYMOUTH AND NORTHEASTERN UNION
COUNTIES...

At 112 AM CDT, a severe thunderstorm was located near Hawarden,
moving east at 30 mph.

HAZARD...Quarter size hail.

SOURCE...Radar indicated.

IMPACT...Damage to vehicles is expected.

This severe storm will be near...
  Ireton and Craig around 130 AM CDT.

Other locations impacted by this severe thunderstorm include
Chatsworth.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4287 9662 4298 9660 4301 9630 4281 9631
TIME...MOT...LOC 0612Z 275DEG 27KT 4294 9648 

HAIL...1.00IN
WIND...<50MPH
 
$$

APT

002 
WWUS53 KFSD 090623
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
123 AM CDT Fri Jul 9 2021

IAC149-167-SDC127-090633-
/O.EXP.KFSD.SV.W.0055.000000T0000Z-210709T0630Z/
Sioux IA-Plymouth IA-Union SD-
123 AM CDT Fri Jul 9 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN SIOUX...
NORTHWESTERN PLYMOUTH AND NORTHEASTERN UNION COUNTIES WILL EXPIRE AT
130 AM CDT...
                
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 will be allowed to expire.  However small hail
and heavy rain are still possible with this thunderstorm.

A Severe Thunderstorm Watch remains in effect until 300 AM CDT for
northwestern Iowa...and southeastern South Dakota.

LAT...LON 4287 9662 4298 9660 4301 9630 4281 9631
TIME...MOT...LOC 0623Z 277DEG 27KT 4293 9638 

$$

APT

The office that day

Everything else NWS Sioux Falls, SD issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 8, 11:45 PM CDT	Severe Thunderstorm Warning	FSD	Woodbury	45 min
Jul 8, 11:50 PM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Sioux	40 min
Jul 9, 12:29 AM CDT	Severe Thunderstorm Warning	FSD	Cherokee, Plymouth	46 min
Jul 9, 12:46 AM CDT	Severe Thunderstorm Warning	FSD	Sioux	44 min
Jul 9, 2:15 AM CDT	Severe Thunderstorm Warning	FSD	Plymouth, Sioux	45 min
Jul 8, 10:53 PM CDT	Severe Thunderstorm Warning	FSD	Bon Homme, Hutchinson, Turner, Yankton	52 min
Jul 8, 10:56 PM CDT	Severe Thunderstorm Warning	FSD	Yankton	19 min
Jul 8, 11:11 PM CDT	Severe Thunderstorm Warning	FSD	Clay, Yankton	34 min
Jul 8, 11:21 PM CDT	Severe Thunderstorm Warning	FSD	Clay, Hutchinson, Lincoln, Turner, Yankton	39 min
Jul 8, 11:59 PM CDT	Severe Thunderstorm Warning	FSD	Clay, Lincoln, Turner, Union	46 min
Jul 9, 1:22 AM CDT	Severe Thunderstorm Warning	FSD	Aurora, Davison, Jerauld, Sanborn	38 min
Jul 9, 2:34 AM CDT	Severe Thunderstorm Warning	FSD	Hanson, Lake, McCook, Miner	41 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2021 Severe Thunderstorm Warnings in South Dakota, 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.