Alert archive / Iowa / Special Weather Statements in 2021

Special Weather Statement, NWS Des Moines, IA

August 24, 2021Black Hawk County, Bremer County, Iowa

NWS Des Moines, IA issued this special weather statement at Aug 24, 2021, 3:00 PM CDT for Black Hawk County, Bremer County, Iowa. It was in force for 30 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 24, 2021, 3:00 PM CDT (20:00 UTC)
Expired
Aug 24, 2021, 3:30 PM CDT
In force
30 min
Issued by
NWS Des Moines, IA
Hail
0.00 in
Wind
40

Counties Black Hawk County, IA, Bremer County, IA

The radar

The Des Moines radar (KDMX), 154 km from the middle of the area, began a volume at 20:01 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

Davenport, (KDVN), launched 12:00Z, 8.0 hours before the alert went out and 172 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, Davenport, at 12:00Z on 2021-08-24Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1809 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, Davenport, at 12:00Z on 2021-08-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 35 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
1809 J/kg
Mixed-layer CIN
-127 J/kg
Mixed-layer LCL
1284 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
35 m²/s²
0-3 km storm-relative helicity
9 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

728 
WWUS83 KDMX 242000
SPSDMX

Special Weather Statement
National Weather Service Des Moines IA
300 PM CDT Tue Aug 24 2021
 
IAZ028-039-242030-
Black Hawk IA-Bremer IA-
300 PM CDT Tue Aug 24 2021

...Strong wind gusts will impact portions of Black Hawk and eastern 
Bremer Counties through 330 PM CDT...

At 259 PM CDT, Doppler radar was tracking strong winds near 
Fairbank, or 7 miles northwest of Oelwein, moving east at 40 mph.

HAZARD...Winds in excess of 40 mph.

SOURCE...Radar indicated.

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

These winds will remain over mainly rural areas of Black Hawk and 
eastern Bremer Counties, including the following locations... 
Raymond, Readlyn, Dunkerton, Washburn, Frederika and Gilbertville.

This includes Interstate 380 between mile markers 56 and 73.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building. 

A Severe Thunderstorm Watch remains in effect until 700 PM CDT for
northeastern Iowa.

&&

LAT...LON 4230 9237 4291 9235 4291 9208 4247 9208
      4247 9207 4230 9206
TIME...MOT...LOC 1959Z 273DEG 36KT 4272 9205 

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

$$

Krull

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 24, 11:06 AM CDTSpecial Weather StatementDMXEmmet24 min
Aug 24, 11:30 AM CDTSpecial Weather StatementDMXKossuth, Winnebago45 min
Aug 24, 12:07 PM CDTSpecial Weather StatementDMXCerro Gordo, Hancock, Worth68 min
Aug 24, 12:26 PM CDTSevere Thunderstorm WarningDMXCerro Gordo, Hancock49 min
Aug 24, 12:51 PM CDTSevere Thunderstorm WarningDMXCerro Gordo, Franklin, Hancock, Wright54 min
Aug 24, 1:18 PM CDTSevere Thunderstorm Warning Considerable damage threatDMXButler57 min
Aug 24, 1:44 PM CDTSevere Thunderstorm WarningDMXButler31 min
Aug 24, 1:53 PM CDTSevere Thunderstorm WarningDMXBlack Hawk, Bremer67 min
Aug 24, 2:17 PM CDTSpecial Weather StatementDMXButler28 min
Aug 24, 3:28 PM CDTSevere Thunderstorm WarningDMXHamilton, Hardin, Marshall, Story47 min
Aug 24, 4:03 PM CDTSevere Thunderstorm WarningDMXBlack Hawk, Grundy, Hardin, Marshall, Poweshiek, Tama57 min

Nearby

Special Weather Statements in Iowa, 2021Every 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.