Alert archive / Iowa / Mesoscale Discussions in 2016

Mesoscale Discussion 1520

August 11, 201629 counties in Iowa; 18 counties in Nebraska; 5 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Aug 11, 2016, 12:37 PM CDT for 29 counties in Iowa; 18 counties in Nebraska; 5 counties in South Dakota. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Aug 11, 2016, 12:37 PM CDT (17:37 UTC)
Expired
Aug 11, 2016, 3:00 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
20%
All 52 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, Franklin County, IA, Greene County, IA, Guthrie County, IA, Hamilton County, IA, Hardin County, IA, Harrison County, IA, Humboldt County, IA, Ida County, IA, Monona County, IA, O'Brien County, IA, Plymouth County, IA, Pocahontas County, IA, Polk County, IA, Sac County, IA, Shelby County, IA, Sioux County, IA, Story County, IA, Webster County, IA, Woodbury County, IA, Wright County, IA, Antelope County, NE, Boone County, NE, Boyd County, NE, Burt County, NE, Cedar County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Garfield County, NE, Holt County, NE, Knox County, NE, Madison County, NE, Pierce County, NE, Rock County, NE, Stanton County, NE, Thurston County, NE, Wayne County, NE, Wheeler County, NE, Bon Homme County, SD, Charles Mix County, SD, Clay County, SD, Union County, SD, Yankton County, SD

The radar

The Omaha radar (KOAX), 104 km from the middle of the area, began a volume at 17:40 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 12:00Z, 5.6 hours before the alert went out and 104 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-pSkew-T log-p diagram, Omaha, NE at 12:00Z on 2016-08-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 847 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Omaha, NE at 12:00Z on 2016-08-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 284 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
847 J/kg
Mixed-layer CIN
-276 J/kg
Mixed-layer LCL
1518 m above ground
0-6 km bulk shear
34 kt
0-1 km storm-relative helicity
284 m²/s²
0-3 km storm-relative helicity
297 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 11, 3:26 PM CDTMesoscale DiscussionSPCAdair, Adams, Audubon, Boone, Buena Vista, Calhoun and 31 more2 hr
Aug 11, 3:55 PM CDTSevere Thunderstorm WatchSPCAdair, Adams, Audubon, Black Hawk, Boone, Bremer and 51 more7 hr
Aug 11, 6:17 PM CDTMesoscale DiscussionSPCAdair, Adams, Audubon, Benton, Black Hawk, Boone and 54 more58 min
Aug 11, 2:35 PM CDTMesoscale DiscussionSPCBanner, Box Butte, Cheyenne, Dawes, Garden, Kimball and 4 more2 hr
Aug 11, 5:31 PM CDTMesoscale DiscussionSPCBlaine, Brown, Lincoln, Logan, Loup, McPherson and 2 more89 min
Aug 11, 5:56 PM CDTMesoscale DiscussionSPCBox Butte, Cherry, Garden, Grant, Morrill, Sheridan94 min
Aug 11, 6:29 PM CDTSevere Thunderstorm WatchSPCArthur, Blaine, Boyd, Brown, Cherry, Custer and 13 more7 hr
Aug 10, 8:00 PM CDTSevere Thunderstorm WatchSPCBeadle, Brookings, Brown, Brule, Buffalo, Campbell and 25 more6 hr
Aug 10, 10:50 PM CDTMesoscale DiscussionSPCAurora, Beadle, Brookings, Brown, Brule, Buffalo and 18 more85 min

Nearby

Mesoscale Discussions in Iowa, 2016Mesoscale Discussions in Nebraska, 2016Mesoscale Discussions in South Dakota, 2016Every mesoscale discussion in 2016

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.