Alert archive / Iowa / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 98, NWS Des Moines, IA

August 26, 20215 counties in Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Aug 26, 2021, 8:18 AM CDT for 5 counties in Iowa. It was in force for 42 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 26, 2021, 8:18 AM CDT (13:18 UTC)
Expired
Aug 26, 2021, 9:00 AM CDT
In force
42 min
Issued by
NWS Des Moines, IA
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Calhoun County, IA, Carroll County, IA, Crawford County, IA, Greene County, IA, Sac County, IA

The radar

The Des Moines radar (KDMX), 103 km from the middle of the area, began a volume at 13:18 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

Omaha, NE (KOAX), launched 12:00Z, 1.3 hours before the alert went out and 176 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 12:00Z on 2021-08-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2002 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 12:00Z on 2021-08-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 217 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
2002 J/kg
Mixed-layer CIN
-261 J/kg
Mixed-layer LCL
1111 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
217 m²/s²
0-3 km storm-relative helicity
264 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.3

Open this sounding in Storm Lab

The text

As transmitted.

319 
WUUS53 KDMX 261318
SVRDMX
IAC025-027-047-073-161-261400-
/O.NEW.KDMX.SV.W.0098.210826T1318Z-210826T1400Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Des Moines IA
818 AM CDT Thu Aug 26 2021

The National Weather Service in Des Moines  has issued a

* Severe Thunderstorm Warning for...
  Western Greene County in west central Iowa...
  Eastern Sac County in west central Iowa...
  Calhoun County in west central Iowa...
  Northeastern Crawford County in west central Iowa...
  Northern Carroll County in west central Iowa...

* Until 900 AM CDT.

* At 818 AM CDT, severe thunderstorms were located along a line
  extending from near Sac City to 8 miles west of Lake City to near
  Carroll, moving east at 40 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

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

* Severe thunderstorms will be near...
  Lake City around 830 AM CDT.
  Glidden, South Twin Lake and North Twin Lake around 835 AM CDT.

Other locations in the path of these severe thunderstorms include
Rockwell City and Jefferson.

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 4228 9518 4252 9516 4255 9444 4247 9444
      4247 9442 4231 9440 4221 9440 4221 9438
      4193 9441 4208 9530
TIME...MOT...LOC 1318Z 282DEG 34KT 4240 9490 4223 9488 4208 9496 

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

$$

Fowle
2 follow-up statements
919 
WWUS53 KDMX 261331
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
831 AM CDT Thu Aug 26 2021

IAC025-027-047-073-161-261400-
/O.CON.KDMX.SV.W.0098.000000T0000Z-210826T1400Z/
Greene IA-Sac IA-Calhoun IA-Crawford IA-Carroll IA-
831 AM CDT Thu Aug 26 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 AM CDT
FOR WESTERN GREENE...EASTERN SAC...CALHOUN...EASTERN CRAWFORD AND
NORTHERN CARROLL COUNTIES...

At 831 AM CDT, severe thunderstorms were located along a line
extending from 6 miles northwest of North Twin Lake to near Lake City
to near Carroll, moving east at 45 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
  Rockwell City, North Twin Lake, South Twin Lake, Manson and 
  Jefferson.

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 4228 9503 4253 9504 4255 9444 4247 9444
      4247 9442 4231 9440 4221 9440 4221 9438
      4193 9441 4205 9513
TIME...MOT...LOC 1331Z 278DEG 38KT 4252 9475 4222 9470 4203 9481 

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

$$

Fowle
848 
WWUS53 KDMX 261346
SVSDMX

Severe Weather Statement
National Weather Service Des Moines IA
846 AM CDT Thu Aug 26 2021

IAC047-161-261356-
/O.CAN.KDMX.SV.W.0098.000000T0000Z-210826T1400Z/
Sac IA-Crawford IA-
846 AM CDT Thu Aug 26 2021

...THE SEVERE THUNDERSTORM WARNING FOR EASTERN SAC AND EASTERN
CRAWFORD COUNTIES IS CANCELLED...

The storms which prompted the warning have moved out of the warned 
area. Therefore, the warning has been cancelled.

LAT...LON 4224 9482 4254 9481 4255 9444 4247 9444
      4247 9442 4231 9440 4221 9440 4221 9438
      4193 9441 4202 9492
TIME...MOT...LOC 1346Z 276DEG 38KT 4247 9452 4222 9451 4202 9465 

$$

IAC025-027-073-261400-
/O.CON.KDMX.SV.W.0098.000000T0000Z-210826T1400Z/
Greene IA-Calhoun IA-Carroll IA-
846 AM CDT Thu Aug 26 2021

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 900 AM CDT
FOR WESTERN GREENE...CALHOUN AND NORTHEASTERN CARROLL COUNTIES...

At 846 AM CDT, severe thunderstorms were located along a line
extending from near Manson to 11 miles east of Lake City to near
Glidden, moving east at 45 mph.

HAZARD...60 mph wind gusts.

SOURCE...Radar indicated.

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

Locations impacted include...
Carroll, Jefferson, Rockwell City, Lake City, Manson, Glidden, North
Twin Lake, South Twin Lake, Pomeroy, Scranton, Churdan, Farnhamville,
Lohrville, Twin Lakes, Lidderdale, Lanesboro, Somers, Ralston,
Knierim and Rinard.

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 4224 9482 4254 9481 4255 9444 4247 9444
      4247 9442 4231 9440 4221 9440 4221 9438
      4193 9441 4202 9492
TIME...MOT...LOC 1346Z 276DEG 38KT 4247 9452 4222 9451 4202 9465 

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

$$

Fowle

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 26, 3:30 AM CDTHeat AdvisoryDMXAdair, Adams, Appanoose, Audubon, Cass, Clarke and 16 more17 hr
Aug 26, 8:03 AM CDTSpecial Weather StatementDMXAudubon, Calhoun, Carroll, Pocahontas, Sac42 min
Aug 26, 8:55 AM CDTSpecial Weather StatementDMXAdair, Audubon, Dallas, Guthrie65 min
Aug 26, 9:18 AM CDTSpecial Weather StatementDMXBoone, Hamilton, Webster57 min
Aug 26, 10:02 AM CDTSpecial Weather StatementDMXDallas, Jasper, Madison, Polk, Warren43 min
Aug 26, 12:29 PM CDTSpecial Weather StatementDMXBoone, Story46 min
Aug 26, 1:46 PM CDTSpecial Weather StatementDMXDavis, Wapello44 min
Aug 26, 2:16 PM CDTSevere Thunderstorm WarningDMXAppanoose, Davis, Wapello44 min
Aug 26, 3:03 PM CDTFlood WatchDMXBlack Hawk, Bremer, Butler, Calhoun, Cerro Gordo, Emmet and 13 more16 hr

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.