Alert archive / Nebraska / Mesoscale Discussions in 2011

Mesoscale Discussion 766

May 12, 201110 counties in Iowa; 36 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at May 12, 2011, 5:35 PM CDT for 10 counties in Iowa; 36 counties in Nebraska. It was in force for 85 min.

The area

The outline as issued.

The facts

Issued: May 12, 2011, 5:35 PM CDT (22:35 UTC)
Expired: May 12, 2011, 7:00 PM CDT
In force: 85 min
Issued by: the Storm Prediction Center

All 46 counties

Calhoun County, IA, Carroll County, IA, Crawford County, IA, Harrison County, IA, Ida County, IA, Monona County, IA, Pottawattamie County, IA, Sac County, IA, Shelby County, IA, Woodbury County, IA, Adams County, NE, Buffalo County, NE, Burt County, NE, Butler County, NE, Cass County, NE, Clay County, NE, Colfax County, NE, Cuming County, NE, Dodge County, NE, Douglas County, NE, Fillmore County, NE, Franklin County, NE, Gage County, NE, Hall County, NE, Hamilton County, NE, Howard County, NE, Jefferson County, NE, Kearney County, NE, Lancaster County, NE, Madison County, NE, Merrick County, NE, Nance County, NE, Nuckolls County, NE, Otoe County, NE, Platte County, NE, Polk County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Stanton County, NE, Thayer County, NE, Thurston County, NE, Washington County, NE, Webster County, NE, York County, NE

The radar

The Omaha radar (KOAX), 60 km from the middle of the area, began a volume at 22:35 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.

Severe Thunderstorm Watch 295May 12, 6:10 PM CDT

The nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 10.6 hours before the alert went out and 60 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: 353 J/kg
Mixed-layer CIN: -73 J/kg
Mixed-layer LCL: 759 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 40 m²/s²
0-3 km storm-relative helicity: 82 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

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
May 11, 8:16 PM CDT	Mesoscale Discussion	SPC	Adams, Fremont, Mills, Montgomery, Page, Taylor	59 min
May 12, 2:37 PM CDT	Tornado Watch	SPC	Harrison, Monona, Shelby	7 hr
May 12, 6:05 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Adams, Audubon, Black Hawk, Boone, Bremer and 32 more	7 hr
May 11, 7:51 PM CDT	Mesoscale Discussion	SPC	Dundy, Frontier, Furnas, Hayes, Hitchcock, Red Willow	84 min
May 12, 2:06 PM CDT	Mesoscale Discussion	SPC	Adams, Boone, Buffalo, Butler, Cass, Clay and 39 more	114 min

Nearby

Mesoscale Discussions in Nebraska, 2011 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.