Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 84, NWS Sioux Falls, SD

August 6, 2021Sioux County, Iowa; Union County, South Dakota

NWS Sioux Falls, SD issued this severe thunderstorm warning at Aug 6, 2021, 1:36 AM CDT for Sioux County, Iowa; Union County, South Dakota. It was in force for 24 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 6, 2021, 1:36 AM CDT (06:36 UTC)
Expired: Aug 6, 2021, 2:00 AM CDT
In force: 24 min
Issued by: NWS Sioux Falls, SD
Area: Storm-based polygon
Hail: 1.25 in
Wind: 60.0 mph

Counties Sioux County, IA, Union County, SD

The radar

The Sioux Falls radar (KFSD), 65 km from the middle of the area, began a volume at 06:34 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.

The nearest sounding before it

Aberdeen, SD (KABR), launched 00:00Z, 6.6 hours before the alert went out and 260 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: 835 J/kg
Mixed-layer CIN: -42 J/kg
Mixed-layer LCL: 1549 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 41 m²/s²
0-3 km storm-relative helicity: 259 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

226 
WUUS53 KFSD 060636
SVRFSD
IAC167-SDC127-060700-
/O.NEW.KFSD.SV.W.0084.210806T0636Z-210806T0700Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Sioux Falls SD
136 AM CDT Fri Aug 6 2021

The National Weather Service in Sioux Falls has issued a

* Severe Thunderstorm Warning for...
  Southwestern Sioux County in northwestern Iowa...
  Northeastern Union County in southeastern South Dakota...

* Until 200 AM CDT.

* At 135 AM CDT, a severe thunderstorm was located near Hudson, or
  near Hawarden, moving southeast at 30 mph.

  HAZARD...60 mph wind gusts and half dollar size hail.

  SOURCE...Radar indicated.

  IMPACT...Hail damage to vehicles is expected. Expect wind damage 
           to roofs, siding, and trees.

* This severe thunderstorm will be near...
  Hawarden around 140 AM CDT.
  Ireton around 155 AM CDT.
  
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4308 9651 4309 9650 4309 9646 4310 9646
      4312 9644 4316 9638 4294 9609 4291 9639
      4291 9646
TIME...MOT...LOC 0635Z 328DEG 28KT 4309 9643 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.25 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Chapman

2 follow-up statements

992 
WWUS53 KFSD 060650
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
150 AM CDT Fri Aug 6 2021

SDC127-060659-
/O.CAN.KFSD.SV.W.0084.000000T0000Z-210806T0700Z/
Union SD-
150 AM CDT Fri Aug 6 2021

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

LAT...LON 4301 9644 4306 9638 4308 9628 4294 9609
      4291 9639
TIME...MOT...LOC 0649Z 328DEG 28KT 4299 9635 

$$

IAC167-060700-
/O.CON.KFSD.SV.W.0084.000000T0000Z-210806T0700Z/
Sioux IA-
150 AM CDT Fri Aug 6 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 200 AM CDT
FOR SOUTHWESTERN SIOUX COUNTY...

At 149 AM CDT, a severe thunderstorm was located near Ireton, or 
near Hawarden, moving southeast at 30 mph.

HAZARD...60 mph wind gusts and half dollar size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

This severe storm will be near...
  Maurice around 200 AM CDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4301 9644 4306 9638 4308 9628 4294 9609
      4291 9639
TIME...MOT...LOC 0649Z 328DEG 28KT 4299 9635 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.25 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Chapman

204 
WWUS53 KFSD 060700
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
200 AM CDT Fri Aug 6 2021

IAC167-060709-
/O.EXP.KFSD.SV.W.0084.000000T0000Z-210806T0700Z/
Sioux IA-
200 AM CDT Fri Aug 6 2021

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHWESTERN SIOUX COUNTY WILL
EXPIRE AT 200 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 dime to 
nickel size hail is still likely with this thunderstorm in areas 
between Ireton and Maurice and toward Struble through 215 am CDT.

LAT...LON 4301 9644 4306 9638 4308 9628 4294 9609
      4291 9639
TIME...MOT...LOC 0659Z 323DEG 27KT 4296 9629 

$$

Chapman

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 5, 8:57 PM CDT	Severe Thunderstorm Warning Considerable damage threat	FSD	Lyon	48 min
Aug 5, 9:31 PM CDT	Severe Thunderstorm Warning	FSD	Lyon, Sioux	44 min
Aug 5, 10:04 PM CDT	Severe Thunderstorm Warning	FSD	Lyon	41 min
Aug 6, 12:10 AM CDT	Severe Thunderstorm Warning	FSD	Woodbury	35 min
Aug 6, 1:06 AM CDT	Severe Thunderstorm Warning	FSD	Lyon, Sioux	39 min
Aug 5, 7:00 PM CDT	Severe Thunderstorm Warning	FSD	Lake, Moody	45 min
Aug 5, 7:28 PM CDT	Severe Thunderstorm Warning	FSD	Brookings, Moody	32 min
Aug 5, 7:44 PM CDT	Severe Thunderstorm Warning	FSD	Moody	33 min
Aug 5, 7:58 PM CDT	Severe Thunderstorm Warning	FSD	Lake, Minnehaha, Moody	47 min
Aug 5, 8:24 PM CDT	Severe Thunderstorm Warning Considerable damage threat	FSD	Minnehaha, Moody	51 min
Aug 5, 9:04 PM CDT	Severe Thunderstorm Warning	FSD	Minnehaha	28 min
Aug 5, 10:36 PM CDT	Severe Thunderstorm Warning	FSD	Clay, Lincoln, Turner, Union	39 min
Aug 5, 11:40 PM CDT	Severe Thunderstorm Warning	FSD	Minnehaha	50 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.