Alert archive / Iowa / Mesoscale Discussions in 2018

Mesoscale Discussion 243

April 13, 201811 counties in Iowa; Atchison County, Missouri

The Storm Prediction Center issued this mesoscale discussion at Apr 13, 2018, 5:31 PM CDT for 11 counties in Iowa; Atchison County, Missouri. It was in force for 29 min.

The area

The outline as issued.

The facts

Issued
Apr 13, 2018, 5:31 PM CDT (22:31 UTC)
Expired
Apr 13, 2018, 6:00 PM CDT
In force
29 min
Issued by
the Storm Prediction Center

Counties Audubon County, IA, Carroll County, IA, Cass County, IA, Fremont County, IA, Greene County, IA, Guthrie County, IA, Mills County, IA, Montgomery County, IA, Page County, IA, Pottawattamie County, IA, Shelby County, IA, Atchison County, MO

The radar

The Des Moines radar (KDMX), 109 km from the middle of the area, began a volume at 22:34 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 nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 10.5 hours before the alert went out and 116 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 2018-04-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 230 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 2018-04-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 342 square meters per square second.1939587897Sfc1 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
230 J/kg
Mixed-layer CIN
-547 J/kg
Mixed-layer LCL
838 m above ground
0-6 km bulk shear
59 kt
0-1 km storm-relative helicity
342 m²/s²
0-3 km storm-relative helicity
346 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.2

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
Apr 13, 8:44 AM CDTMesoscale DiscussionSPCAllamakee, Dickinson, Emmet, Howard, Lyon, Mitchell and 4 more3 hr
Apr 13, 2:06 PM CDTMesoscale DiscussionSPCAdair, Adams, Cass, Clarke, Decatur, Fremont and 8 more2 hr
Apr 13, 2:19 PM CDTTornado WatchSPCAdair, Adams, Appanoose, Cass, Clarke, Davis and 17 more7 hr
Apr 13, 3:22 PM CDTSevere Thunderstorm WatchSPCAudubon, Black Hawk, Boone, Calhoun, Carroll, Dallas and 13 more6 hr
Apr 13, 12:39 PM CDTMesoscale DiscussionSPCBarton, Jasper, McDonald, Newton2 hr
Apr 13, 1:20 PM CDTTornado WatchSPCBarry, Barton, Cedar, Christian, Dade, Greene and 9 more9 hr
Apr 13, 3:43 PM CDTMesoscale DiscussionSPCBarry, Barton, Dade, Jasper, Lawrence, McDonald and 1 more92 min
Apr 13, 5:08 PM CDTMesoscale DiscussionSPCBenton, Camden, Carter, Christian, Cole, Dallas and 23 more2 hr
Apr 13, 5:27 PM CDTTornado WatchSPCBollinger, Butler, Camden, Cape Girardeau, Carter, Crawford and 33 more8 hr
Apr 13, 5:53 PM CDTMesoscale DiscussionSPCDunklin97 min

Nearby

Mesoscale Discussions in Iowa, 2018Mesoscale Discussions in Missouri, 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.