Alert archive / Iowa / Mesoscale Discussions in 2011

Mesoscale Discussion 2099

September 2, 201128 counties in Iowa

The Storm Prediction Center issued this mesoscale discussion at Sep 2, 2011, 10:04 PM CDT for 28 counties in Iowa. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued: Sep 2, 2011, 10:04 PM CDT (03:04 UTC)
Expired: Sep 2, 2011, 11:30 PM CDT
In force: 86 min
Issued by: the Storm Prediction Center

All 28 counties

Adair County, IA, Adams County, IA, Audubon County, IA, Benton County, IA, Black Hawk County, IA, Boone County, IA, Buchanan County, IA, Cass County, IA, Dallas County, IA, Delaware County, IA, Greene County, IA, Grundy County, IA, Guthrie County, IA, Hamilton County, IA, Hardin County, IA, Iowa County, IA, Jasper County, IA, Johnson County, IA, Linn County, IA, Madison County, IA, Marion County, IA, Marshall County, IA, Polk County, IA, Poweshiek County, IA, Story County, IA, Tama County, IA, Union County, IA, Warren County, IA

The radar

The Des Moines radar (KDMX), 5 km from the middle of the area, began a volume at 03:05 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 3.1 hours before the alert went out and 224 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: 1444 J/kg
Mixed-layer CIN: -127 J/kg
Mixed-layer LCL: 1002 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 102 m²/s²
0-3 km storm-relative helicity: 170 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 6.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 2, 10:23 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Benton, Black Hawk, Boone, Buchanan, Cass and 26 more	6 hr
Sep 2, 11:56 PM CDT	Mesoscale Discussion	SPC	Benton, Black Hawk, Boone, Buchanan, Cedar, Clayton and 26 more	94 min
Sep 3, 12:48 AM CDT	Severe Thunderstorm Watch	SPC	Clayton, Fayette	6 hr

Nearby

Mesoscale Discussions in Iowa, 2011 Every mesoscale discussion in 2011

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.