Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 116, NWS Sioux Falls, SD

August 27, 2021Buena Vista County, Iowa

NWS Sioux Falls, SD issued this severe thunderstorm warning at Aug 27, 2021, 2:00 AM CDT for Buena Vista County, Iowa. It was in force for 60 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 27, 2021, 2:00 AM CDT (07:00 UTC)
Expired
Aug 27, 2021, 3:00 AM CDT
In force
60 min
Issued by
NWS Sioux Falls, SD
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

County Buena Vista County, IA

The radar

The Sioux Falls radar (KFSD), 159 km from the middle of the area, began a volume at 06:58 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Aug 26, 8:03 PM CDTSevere Thunderstorm WatchSPC7 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 7.0 hours before the alert went out and 181 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-pSkew-T log-p diagram, Omaha, NE at 00:00Z on 2021-08-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 5342 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Omaha, NE at 00:00Z on 2021-08-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 111 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
5342 J/kg
Mixed-layer CIN
-16 J/kg
Mixed-layer LCL
1163 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
111 m²/s²
0-3 km storm-relative helicity
199 m²/s²
Significant tornado parameter
3.8
Supercell composite
24.0

Open this sounding in Storm Lab

The text

As transmitted.

657 
WUUS53 KFSD 270700
SVRFSD
IAC021-270800-
/O.NEW.KFSD.SV.W.0116.210827T0700Z-210827T0800Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Sioux Falls SD
200 AM CDT Fri Aug 27 2021

The National Weather Service in Sioux Falls has issued a

* Severe Thunderstorm Warning for...
  Buena Vista County in northwestern Iowa...

* Until 300 AM CDT.

* At 200 AM CDT, severe thunderstorms were located along a line
  extending from near Larrabee to near Aurelia to near Holstein,
  moving east at 45 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Severe thunderstorms will be near...
  Alta around 215 AM CDT.
  Storm Lake around 220 AM CDT.

Other locations in the path of these severe thunderstorms include
Linn Grove, Truesdale, Sioux Rapids, Lakeside, Newell, Albert City
and Marathon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4256 9539 4290 9538 4289 9491 4256 9492
TIME...MOT...LOC 0700Z 260DEG 38KT 4289 9556 4270 9551 4253 9557 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Weisser
2 follow-up statements
828 
WWUS53 KFSD 270723
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
223 AM CDT Fri Aug 27 2021

IAC021-270800-
/O.CON.KFSD.SV.W.0116.000000T0000Z-210827T0800Z/
Buena Vista IA-
223 AM CDT Fri Aug 27 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 300 AM CDT
FOR BUENA VISTA COUNTY...

At 223 AM CDT, severe thunderstorms were located along a line
extending from Peterson to near Truesdale to 6 miles northeast of
Galva, moving east at 40 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
  Truesdale, Sioux Rapids, Lakeside, Newell, Albert City and 
  Marathon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Torrential rainfall is occurring with these storms, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 4256 9539 4290 9538 4289 9491 4256 9492
TIME...MOT...LOC 0723Z 263DEG 33KT 4292 9531 4273 9526 4256 9532 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...<.75 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Weisser
147 
WWUS53 KFSD 270752
SVSFSD

Severe Weather Statement
National Weather Service Sioux Falls SD
252 AM CDT Fri Aug 27 2021

IAC021-270802-
/O.EXP.KFSD.SV.W.0116.000000T0000Z-210827T0800Z/
Buena Vista IA-
252 AM CDT Fri Aug 27 2021

...THE SEVERE THUNDERSTORM WARNING FOR BUENA VISTA COUNTY WILL EXPIRE
AT 300 AM CDT...
            
The storms which prompted the warning have weakened below severe
limits, and no longer pose an immediate threat to life or property.
Therefore, the warning will be allowed to expire.  However gusty
winds and heavy rain are still possible with these thunderstorms.

A Severe Thunderstorm Watch remains in effect until 300 AM CDT for
northwestern and west central Iowa.

LAT...LON 4256 9539 4290 9538 4289 9491 4256 9492
TIME...MOT...LOC 0752Z 260DEG 38KT 4297 9492 4278 9487 4261 9493 

$$

Weisser

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 27, 12:17 AM CDTSevere Thunderstorm WarningFSDLyon, Sioux28 min
Aug 27, 12:34 AM CDTSevere Thunderstorm Warning Considerable damage threatFSDPlymouth, Sioux41 min
Aug 27, 1:04 AM CDTTornado WarningFSDSioux26 min
Aug 27, 1:09 AM CDTSevere Thunderstorm Warning Considerable damage threatFSDCherokee, Lyon, O'Brien, Osceola, Plymouth, Sioux51 min
Aug 27, 1:25 AM CDTSevere Thunderstorm Warning Considerable damage threatFSDCherokee, Ida, Plymouth, Woodbury50 min
Aug 27, 1:52 AM CDTSevere Thunderstorm WarningFSDBuena Vista, Cherokee, Clay, Dickinson, O'Brien, Osceola68 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2021Every 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.