Alert archive / Iowa / Mesoscale Discussions in 2007

Mesoscale Discussion 1645

August 4, 200722 counties in Iowa; 19 counties in Nebraska; 8 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Aug 4, 2007, 2:51 PM CDT for 22 counties in Iowa; 19 counties in Nebraska; 8 counties in South Dakota. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued: Aug 4, 2007, 2:51 PM CDT (19:51 UTC)
Expired: Aug 4, 2007, 4:45 PM CDT
In force: 114 min
Issued by: the Storm Prediction Center

All 49 counties

Audubon County, IA, Boone County, IA, Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Dallas County, IA, Greene County, IA, Guthrie County, IA, Ida County, IA, Lyon County, IA, Monona County, IA, O'Brien County, IA, Osceola County, IA, Plymouth County, IA, Pocahontas County, IA, Sac County, IA, Sioux County, IA, Webster County, IA, Woodbury County, IA, Antelope County, NE, Boone County, NE, Burt County, NE, Cedar County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Garfield County, NE, Greeley County, NE, Holt County, NE, Knox County, NE, Loup County, NE, Madison County, NE, Pierce County, NE, Stanton County, NE, Thurston County, NE, Valley County, NE, Wayne County, NE, Wheeler County, NE, Bon Homme County, SD, Clay County, SD, Hutchinson County, SD, Lincoln County, SD, McCook County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Omaha radar (KOAX), 102 km from the middle of the area, began a volume at 19:54 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

N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 7.9 hours before the alert went out and 311 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: 41 J/kg
Mixed-layer CIN: -331 J/kg
Mixed-layer LCL: 1432 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 130 m²/s²
0-3 km storm-relative helicity: 104 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

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
Aug 4, 1:49 AM CDT	Mesoscale Discussion	SPC	Buena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 7 more	86 min
Aug 4, 1:01 PM CDT	Mesoscale Discussion	SPC	Des Moines, Henry, Jefferson, Lee, Louisa, Van Buren	2 hr
Aug 4, 3:55 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Adams, Appanoose, Audubon, Boone, Buena Vista and 50 more	6 hr
Aug 4, 6:09 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Appanoose, Audubon, Boone, Buena Vista and 40 more	66 min
Aug 3, 8:02 PM CDT	Mesoscale Discussion	SPC	Antelope, Blaine, Boyd, Brown, Cherry, Garfield and 8 more	118 min
Aug 4, 5:06 PM CDT	Mesoscale Discussion	SPC	Chase, Custer, Dawson, Dundy, Frontier, Garfield and 12 more	114 min
Aug 4, 5:46 PM CDT	Severe Thunderstorm Watch	SPC	Blaine, Buffalo, Custer, Dawson, Frontier, Garfield and 12 more	4 hr

Nearby

Mesoscale Discussions in Iowa, 2007 Mesoscale Discussions in Nebraska, 2007 Mesoscale Discussions in South Dakota, 2007 Every mesoscale discussion in 2007

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.