Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 88, NWS Des Moines, IA

August 10, 20214 counties in Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Aug 10, 2021, 3:00 PM CDT for 4 counties in Iowa. It was in force for 60 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: Aug 10, 2021, 3:00 PM CDT (20:00 UTC)
Expired: Aug 10, 2021, 4:00 PM CDT
In force: 60 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Jasper County, IA, Marshall County, IA, Poweshiek County, IA, Tama County, IA

The radar

The Des Moines radar (KDMX), 90 km from the middle of the area, began a volume at 20:02 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
Aug 10, 3:00 PM CDT	TSTM WND DMG	2 Sw Ferguson, IA	SPOTTER REPORT OF STRONG WINDS WITH POWER OUT. TIME ESTIMATED VIA RADAR.
Aug 10, 3:17 PM CDT	TSTM WND GST 60	2 E Le Grand, IA	PUBLIC REPORT OF 60 PLUS MPH WIND GUST EAST OF LE GRAND, SIGNIFICANTLY REDUCED VISIBILITY ON HWY 30.

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
Aug 10, 2:08 PM CDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 8.0 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: 3755 J/kg
Mixed-layer CIN: -67 J/kg
Mixed-layer LCL: 819 m above ground
0-6 km bulk shear: 12 kt
0-1 km storm-relative helicity: -37 m²/s²
0-3 km storm-relative helicity: 4 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

512 
WUUS53 KDMX 102000
SVRDMX
IAC099-127-157-171-102100-
/O.NEW.KDMX.SV.W.0088.210810T2000Z-210810T2100Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Des Moines IA
300 PM CDT Tue Aug 10 2021

The National Weather Service in Des Moines  has issued a

* Severe Thunderstorm Warning for...
  Northern Poweshiek County in central Iowa...
  Southeastern Marshall County in central Iowa...
  Tama County in central Iowa...
  Northeastern Jasper County in central Iowa...

* Until 400 PM CDT.

* At 300 PM CDT, a severe thunderstorm was located 8 miles southwest
  of Meskwaki Casino, or 11 miles north of Grinnell, moving east at
  40 mph.

  HAZARD...60 mph wind gusts and quarter 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...
  Meskwaki Casino around 310 PM CDT.
  Toledo and Tama around 320 PM CDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4175 9292 4196 9300 4220 9261 4230 9230
      4179 9230
TIME...MOT...LOC 2000Z 250DEG 35KT 4190 9277 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Krull

2 follow-up statements

160 
WWUS53 KDMX 102019
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
319 PM CDT Tue Aug 10 2021

IAC099-127-157-171-102100-
/O.CON.KDMX.SV.W.0088.000000T0000Z-210810T2100Z/
Poweshiek IA-Marshall IA-Tama IA-Jasper IA-
319 PM CDT Tue Aug 10 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM CDT
FOR NORTHERN POWESHIEK...SOUTHEASTERN MARSHALL...TAMA AND
NORTHEASTERN JASPER COUNTIES...

At 318 PM CDT, a severe thunderstorm was located over Tama, or over
Toledo, moving east at 40 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Public. Report of 60 MPH wind gust along Hwy. 30 near Le 
         Grand at 314 PM.

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

This severe thunderstorm will remain over mainly rural areas of
northern Poweshiek, southeastern Marshall, Tama and northeastern
Jasper Counties, including the following locations... Le Grand,
Ferguson, Tf Clark State Park, Laurel, Haverhill, Elberon, Montour,
Garwin, Gilman and Toledo Municipal Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4179 9285 4196 9300 4220 9261 4230 9230
      4179 9230 4178 9276
TIME...MOT...LOC 2018Z 250DEG 35KT 4196 9254 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...OBSERVED
MAX WIND GUST...60 MPH

$$

Krull

746 
WWUS53 KDMX 102040
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
340 PM CDT Tue Aug 10 2021

IAC099-127-157-171-102100-
/O.CON.KDMX.SV.W.0088.000000T0000Z-210810T2100Z/
Poweshiek IA-Marshall IA-Tama IA-Jasper IA-
340 PM CDT Tue Aug 10 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM CDT
FOR NORTHERN POWESHIEK...SOUTHEASTERN MARSHALL...TAMA AND
NORTHEASTERN JASPER COUNTIES...

At 339 PM CDT, a severe thunderstorm was located near Keystone, or 15
miles southwest of Vinton, moving east at 50 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated. This storm has a history of producing 60 
         MPH wind gusts. 

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

Locations impacted include...
Toledo, Tama, Traer, Dysart, Meskwaki Casino, Le Grand, Garwin,
Gilman, Holiday Lake, Chelsea, Montour, Clutier, Elberon, Ferguson,
Hartwick, Vining, Tf Clark State Park and Toledo Municipal Airport.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 4182 9282 4197 9290 4218 9262 4230 9230
      4179 9230 4178 9276
TIME...MOT...LOC 2039Z 252DEG 43KT 4203 9227 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Krull

The office that day

Everything else NWS Des Moines, IA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 10, 12:50 PM CDT	Severe Thunderstorm Warning	DMX	Clarke	25 min
Aug 10, 12:56 PM CDT	Heat Advisory	DMX	Adair, Adams, Appanoose, Audubon, Cass, Clarke and 18 more	30 hr
Aug 10, 1:48 PM CDT	Severe Thunderstorm Warning	DMX	Black Hawk, Bremer, Butler	42 min
Aug 10, 2:14 PM CDT	Severe Thunderstorm Warning	DMX	Black Hawk, Bremer	46 min
Aug 10, 2:57 PM CDT	Severe Thunderstorm Warning	DMX	Black Hawk	18 min
Aug 10, 3:59 PM CDT	Special Weather Statement	DMX	Tama	46 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.