Alert archive / Iowa / Mesoscale Discussions in 2012

Mesoscale Discussion 728

May 6, 201214 counties in Iowa; Atchison County, Nodaway County, Worth County, Missouri; 5 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at May 6, 2012, 4:55 AM CDT for 14 counties in Iowa; Atchison County, Nodaway County, Worth County, Missouri; 5 counties in Nebraska. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
May 6, 2012, 4:55 AM CDT (09:55 UTC)
Expired
May 6, 2012, 7:00 AM CDT
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
40%
All 22 counties

Adair County, IA, Adams County, IA, Audubon County, IA, Cass County, IA, Fremont County, IA, Guthrie County, IA, Mills County, IA, Montgomery County, IA, Page County, IA, Pottawattamie County, IA, Ringgold County, IA, Shelby County, IA, Taylor County, IA, Union County, IA, Atchison County, MO, Nodaway County, MO, Worth County, MO, Cass County, NE, Johnson County, NE, Nemaha County, NE, Otoe County, NE, Sarpy County, NE

The radar

The Omaha radar (KOAX), 90 km from the middle of the area, began a volume at 09:56 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 00:00Z, 9.9 hours before the alert went out and 90 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 00:00Z on 2012-05-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2892 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 00:00Z on 2012-05-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 42 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
2892 J/kg
Mixed-layer CIN
-51 J/kg
Mixed-layer LCL
1936 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
42 m²/s²
0-3 km storm-relative helicity
89 m²/s²
Significant tornado parameter
0.1
Supercell composite
6.4

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.

IssuedProductOfficeCountiesLasted
May 5, 10:03 PM CDTSevere Thunderstorm WatchSPCBuena Vista, Cherokee, Clay, Dickinson, Ida, Lyon and 6 more7 hr
May 5, 11:31 PM CDTMesoscale DiscussionSPCLyon89 min
May 6, 2:12 AM CDTMesoscale DiscussionSPCBuena Vista, Butler, Cerro Gordo, Cherokee, Clay, Dickinson and 17 more63 min
May 6, 7:17 AM CDTSevere Thunderstorm WatchSPCAdair, Adams, Appanoose, Clarke, Dallas, Davis and 16 more6 hr
May 6, 8:40 AM CDTMesoscale DiscussionSPCCedar, Clinton, Des Moines, Henry, Iowa, Jefferson and 9 more65 min
May 6, 9:29 AM CDTSevere Thunderstorm WatchSPCBenton, Cedar, Clinton, Des Moines, Henry, Iowa and 12 more4 hr
May 6, 1:42 PM CDTSevere Thunderstorm WatchSPCDes Moines, Henry, Lee, Louisa, Van Buren7 hr
May 6, 3:56 PM CDTMesoscale DiscussionSPCLee64 min
May 6, 1:22 PM CDTMesoscale DiscussionSPCAudrain, Benton, Boone, Callaway, Chariton, Cooper and 13 more53 min
May 6, 2:40 PM CDTMesoscale DiscussionSPCPlatte95 min
May 6, 3:49 PM CDTSevere Thunderstorm WatchSPCAndrew, Bates, Buchanan, Cass, Clay, Clinton and 10 more7 hr

Nearby

Mesoscale Discussions in Iowa, 2012Mesoscale Discussions in Nebraska, 2012Mesoscale Discussions in Missouri, 2012Every mesoscale discussion in 2012

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.