Alert archive / Iowa / Special Weather Statements in 2021

Special Weather Statement, NWS Des Moines, IA

August 6, 20214 counties in Iowa

NWS Des Moines, IA issued this special weather statement at Aug 6, 2021, 1:21 AM CDT for 4 counties in Iowa. It was in force for 54 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, 1:21 AM CDT (06:21 UTC)
Expired: Aug 6, 2021, 2:15 AM CDT
In force: 54 min
Issued by: NWS Des Moines, IA
Hail: 0.00 in
Wind: 40

Counties Adair County, IA, Adams County, IA, Cass County, IA, Madison County, IA

The radar

The Des Moines radar (KDMX), 99 km from the middle of the area, began a volume at 06:21 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

Topeka, KS (KTOP), launched 00:00Z, 6.4 hours before the alert went out and 259 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: 1591 J/kg
Mixed-layer CIN: -54 J/kg
Mixed-layer LCL: 1531 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 71 m²/s²
0-3 km storm-relative helicity: 218 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 4.8

Open this sounding in Storm Lab

The text

As transmitted.

862 
WWUS83 KDMX 060621
SPSDMX

Special Weather Statement
National Weather Service Des Moines IA
121 AM CDT Fri Aug 6 2021
 
IAZ058-059-070>072-081-082-060715-
Guthrie IA-Adams IA-Adair IA-Union IA-Madison IA-Dallas IA-Cass IA-
121 AM CDT Fri Aug 6 2021

...Strong thunderstorms will impact portions of Madison, Cass,
northwestern Union, southeastern Guthrie, Adams, southwestern Dallas
and Adair Counties through 215 AM CDT...

At 121 AM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 7 miles northeast of Stuart to 11 miles south
of Guthrie Center to 7 miles east of Atlantic to 7 miles north of
Griswold. Movement was southeast at 35 mph.

HAZARD...Winds in excess of 40 mph. The Atlantic airport reported a 
         wind gust of 37 mph around 110am.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around 
         unsecured objects.

Strong thunderstorms will be near...
  Stuart around 125 AM CDT.
  Earlham around 135 AM CDT.

Other locations in the path of these storms include Greenfield,
Winterset, Lake Icaria and Corning.

This includes Interstate 80 between mile markers 73 and 107.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building. 

&&

LAT...LON 4116 9493 4116 9516 4134 9515 4168 9417
      4121 9384 4105 9442 4092 9492
TIME...MOT...LOC 0621Z 326DEG 29KT 4159 9424 4151 9454 4141 9488 4134
9514

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

$$

Ansorge

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 5, 10:11 PM CDT	Special Weather Statement	DMX	Calhoun, Palo Alto, Pocahontas	64 min
Aug 6, 12:24 AM CDT	Special Weather Statement	DMX	Audubon, Guthrie	66 min

Nearby

Special Weather Statements in Iowa, 2021 Every special weather statement 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.