Alert archive / Iowa / Mesoscale Discussions in 2018

Mesoscale Discussion 780

June 18, 201839 counties in Iowa; 37 counties in Nebraska; Union County, South Dakota

The Storm Prediction Center issued this mesoscale discussion at Jun 18, 2018, 1:34 PM CDT for 39 counties in Iowa; 37 counties in Nebraska; Union County, South Dakota. It was in force for 56 min.

The area

The outline as issued.

The facts

Issued
Jun 18, 2018, 1:34 PM CDT (18:34 UTC)
Expired
Jun 18, 2018, 2:30 PM CDT
In force
56 min
Issued by
the Storm Prediction Center
Chance of a watch
80%
All 77 counties

Adair County, IA, Adams County, IA, Audubon County, IA, Boone County, IA, Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cass County, IA, Cerro Gordo County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Dallas County, IA, Franklin County, IA, Fremont County, IA, Greene County, IA, Guthrie County, IA, Hamilton County, IA, Hancock County, IA, Hardin County, IA, Harrison County, IA, Humboldt County, IA, Ida County, IA, Kossuth County, IA, Mills County, IA, Monona County, IA, Montgomery County, IA, O'Brien County, IA, Palo Alto County, IA, Plymouth County, IA, Pocahontas County, IA, Pottawattamie County, IA, Sac County, IA, Shelby County, IA, Story County, IA, Webster County, IA, Winnebago County, IA, Woodbury County, IA, Wright County, IA, Antelope County, NE, Boone County, NE, Burt County, NE, Butler County, NE, Cass County, NE, Cedar County, NE, Clay County, NE, Colfax County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Dodge County, NE, Douglas County, NE, Fillmore County, NE, Gage County, NE, Hamilton County, NE, Jefferson County, NE, Johnson County, NE, Lancaster County, NE, Madison County, NE, Merrick County, NE, Nance County, NE, Nuckolls County, NE, Otoe County, NE, Pierce 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, Wayne County, NE, York County, NE, Union County, SD

The radar

The Omaha radar (KOAX), 62 km from the middle of the area, began a volume at 18:38 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, 6.6 hours before the alert went out and 62 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 2018-06-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 301 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 2018-06-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 84 square meters per square second.1939Sfc1 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
301 J/kg
Mixed-layer CIN
-106 J/kg
Mixed-layer LCL
1177 m above ground
0-6 km bulk shear
27 kt
0-1 km storm-relative helicity
84 m²/s²
0-3 km storm-relative helicity
66 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

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
Jun 18, 3:05 PM CDTSevere Thunderstorm WatchSPCAdair, Audubon, Black Hawk, Boone, Bremer, Buena Vista and 35 more6 hr
Jun 18, 5:46 PM CDTMesoscale DiscussionSPCAdair, Adams, Audubon, Black Hawk, Boone, Bremer and 38 more119 min
Jun 17, 9:27 PM CDTMesoscale DiscussionSPCBlaine, Custer, Lincoln, Logan, Loup, Thomas63 min

Nearby

Mesoscale Discussions in Iowa, 2018Mesoscale Discussions in Nebraska, 2018Mesoscale Discussions in South Dakota, 2018Every mesoscale discussion in 2018

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.