Alert archive / Iowa / Severe Thunderstorm Warnings in 2013

Severe Thunderstorm Warning 109, NWS Des Moines, IA

May 29, 2013Crawford County, Sac County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at May 29, 2013, 8:22 PM CDT for Crawford County, Sac County, Iowa. It was in force for 53 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: May 29, 2013, 8:22 PM CDT (01:22 UTC)
Expired: May 29, 2013, 9:15 PM CDT
In force: 53 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Tornado: Possible
Hail: 0.75 in
Wind: 60.0 mph

Counties Crawford County, IA, Sac County, IA

The radar

The Omaha radar (KOAX), 136 km from the middle of the area, began a volume at 01:24 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
May 29, 6:24 PM CDT	Tornado Watch	SPC	4 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 1.4 hours before the alert went out and 136 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: 1667 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 572 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 249 m²/s²
0-3 km storm-relative helicity: 249 m²/s²
Significant tornado parameter: 1.9
Supercell composite: 9.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Des Moines, IA wrote its last area forecast discussion before this severe thunderstorm warning went out at May 29, 7:09 PM CDT, 1 hour 13 minutes earlier.

Area forecast discussion, May 29, 7:09 PM CDT, 1 hour 13 minutes before

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Hazardous weather outlook, May 29, 7:53 PM CDT, 29 minutes before

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In the hours before

Local storm report, May 29, 6:36 PM CDT, 1 hour 46 minutes before

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Local storm report, May 29, 6:59 PM CDT, 1 hour 23 minutes before

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Local storm report, May 29, 7:04 PM CDT, 1 hour 18 minutes before

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Local storm report, May 29, 7:15 PM CDT, 1 hour 7 minutes before

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Local storm report, May 29, 7:25 PM CDT, 57 minutes before

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Local storm report, May 29, 7:35 PM CDT, 47 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
May 29, 8:35 PM CDT	Areal Flood Warning	DMX	Butler, Franklin, Grundy, Hardin	24 hr
May 29, 8:54 PM CDT	River Flood Warning	DMX	Polk, Story	59 hr
May 29, 9:28 PM CDT	Areal Flood Warning	DMX	Grundy, Hardin, Marshall, Story	24 hr
May 29, 10:00 PM CDT	River Flood Warning	DMX	Black Hawk, Butler	59 hr
May 29, 10:25 PM CDT	Areal Flood Warning	DMX	Black Hawk, Bremer, Tama	24 hr

Nearby

Severe Thunderstorm Warnings in Iowa, 2013 Every severe thunderstorm warning in 2013

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.