Alert archive / Iowa / Severe Thunderstorm Warnings in 1999

Severe Thunderstorm Warning 79, NWS Des Moines, IA

June 9, 1999Polk County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Jun 9, 1999, 7:20 PM CDT for Polk County, Iowa. It was in force for 35 min. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Jun 9, 1999, 7:20 PM CDT (00:20 UTC)
Expired: Jun 9, 1999, 7:55 PM CDT
In force: 35 min
Issued by: NWS Des Moines, IA
Area: Whole counties

County Polk County, IA

The radar

The Des Moines radar (KDMX), 13 km from the middle of the area, began a volume at 00:23 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.

What was reported inside it

Time	Report	Where	Remark
Jun 9, 7:23 PM CDT	Thunderstorm Wind 53	Johnston, IA

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 0.3 hours before the alert went out and 236 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: 1592 J/kg
Mixed-layer CIN: -84 J/kg
Mixed-layer LCL: 1308 m above ground
0-6 km bulk shear: 24 kt
0-1 km storm-relative helicity: 107 m²/s²
0-3 km storm-relative helicity: 145 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.5

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

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 Jun 9, 2:50 PM CDT, 4 hours 30 minutes earlier.

Area forecast discussion, Jun 9, 2:50 PM CDT, 4 hours 30 minutes before

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In the hours before

Local storm report, Jun 9, 4:44 PM CDT, 2 hours 36 minutes before

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Special weather statement, Jun 9, 5:04 PM CDT, 2 hours 16 minutes before

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Local storm report, Jun 9, 6:19 PM CDT, 1 hour 1 minute 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
Jun 9, 7:38 PM CDT	Severe Thunderstorm Warning	DMX	Story	32 min
Jun 10, 9:24 AM CDT	Severe Thunderstorm Warning	DMX	Adams, Union	31 min
Jun 10, 9:32 AM CDT	Severe Thunderstorm Warning	DMX	Ringgold	33 min
Jun 10, 10:10 AM CDT	Severe Thunderstorm Warning	DMX	Clarke, Madison	35 min

Nearby

Severe Thunderstorm Warnings in Iowa, 1999 Every severe thunderstorm warning in 1999

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.