Alert archive / Iowa / Special Weather Statements in 2021

Special Weather Statement, NWS Des Moines, IA

August 8, 2021Story County, Iowa

NWS Des Moines, IA issued this special weather statement at Aug 8, 2021, 1:41 AM CDT for Story County, Iowa. It was in force for 49 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 8, 2021, 1:41 AM CDT (06:41 UTC)
Expired: Aug 8, 2021, 2:30 AM CDT
In force: 49 min
Issued by: NWS Des Moines, IA
Hail: 0.50 in
Wind: 40

County Story County, IA

The radar

The Des Moines radar (KDMX), 33 km from the middle of the area, began a volume at 06:39 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 00:00Z, 6.7 hours before the alert went out and 243 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: 2933 J/kg
Mixed-layer CIN: -124 J/kg
Mixed-layer LCL: 1327 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 149 m²/s²
0-3 km storm-relative helicity: 195 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 3.3

Open this sounding in Storm Lab

The text

As transmitted.

197 
WWUS83 KDMX 080641
SPSDMX

Special Weather Statement
National Weather Service Des Moines IA
141 AM CDT Sun Aug 8 2021
 
IAZ036-037-047>049-080730-
Hamilton IA-Boone IA-Story IA-Hardin IA-Marshall IA-
141 AM CDT Sun Aug 8 2021

...Strong thunderstorms will impact portions of northwestern Polk,
Story, west central Marshall, southwestern Hardin, eastern Boone and
southeastern Hamilton Counties through 230 AM CDT...

At 141 AM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Gilbert to near Huxley. Movement was
northeast at 40 mph.

HAZARD...Winds in excess of 40 mph and half inch hail. The Boone 
         airport recently gusted to 40 mph.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around 
         unsecured objects. Minor damage to outdoor objects is 
         possible.

Strong thunderstorms will be near...
  Ames and Gilbert around 145 AM CDT.
  Iowa State Center around 150 AM CDT.
  Story City around 155 AM CDT.
  Nevada and Roland around 200 AM CDT.

This includes Interstate 35 between mile markers 104 and 135.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building. 

&&

LAT...LON 4186 9371 4186 9378 4210 9389 4245 9339
      4198 9314
TIME...MOT...LOC 0641Z 227DEG 33KT 4211 9375 4192 9365 

MAX HAIL SIZE...0.50 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 8, 12:03 AM CDT	Special Weather Statement	DMX	Adams, Taylor	57 min
Aug 8, 12:26 AM CDT	Special Weather Statement	DMX	Greene	49 min
Aug 8, 12:45 AM CDT	Special Weather Statement	DMX	Greene	30 min
Aug 8, 12:51 AM CDT	Special Weather Statement	DMX	Decatur, Ringgold, Union	54 min
Aug 8, 1:20 AM CDT	Special Weather Statement	DMX	Tama	55 min
Aug 8, 1:29 AM CDT	Special Weather Statement	DMX	Clarke, Decatur, Lucas, Wayne	46 min
Aug 8, 2:03 AM CDT	Special Weather Statement	DMX	Grundy, Hardin	42 min
Aug 8, 2:24 AM CDT	Special Weather Statement	DMX	Black Hawk	51 min
Aug 8, 3:11 AM CDT	Special Weather Statement	DMX	Black Hawk	64 min
Aug 8, 3:39 PM CDT	Heat Advisory	DMX	Adair, Adams, Appanoose, Black Hawk, Boone, Bremer and 26 more	51 hr

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.