Alert archive / Iowa / Mesoscale Discussions in 2009

Mesoscale Discussion 581

April 26, 200919 counties in Iowa; Atchison County, Missouri; 9 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Apr 26, 2009, 12:30 PM CDT for 19 counties in Iowa; Atchison County, Missouri; 9 counties in Nebraska. It was in force for 60 min.

The area

The outline as issued.

The facts

Issued
Apr 26, 2009, 12:30 PM CDT (17:30 UTC)
Expired
Apr 26, 2009, 1:30 PM CDT
In force
60 min
Issued by
the Storm Prediction Center
All 29 counties

Adair County, IA, Adams County, IA, Audubon County, IA, Boone County, IA, Cass County, IA, Dallas County, IA, Fremont County, IA, Greene County, IA, Guthrie County, IA, Madison County, IA, Mills County, IA, Montgomery County, IA, Page County, IA, Polk County, IA, Pottawattamie County, IA, Story County, IA, Taylor County, IA, Union County, IA, Warren County, IA, Atchison County, MO, Cass County, NE, Gage County, NE, Jefferson County, NE, Johnson County, NE, Nemaha County, NE, Otoe County, NE, Pawnee County, NE, Richardson County, NE, Sarpy County, NE

The radar

The Omaha radar (KOAX), 97 km from the middle of the area, began a volume at 17:32 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, 5.5 hours before the alert went out and 97 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 2009-04-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2009-04-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 457 square meters per square second.19395878Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
538 m above ground
0-6 km bulk shear
51 kt
0-1 km storm-relative helicity
457 m²/s²
0-3 km storm-relative helicity
572 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.0

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.

IssuedProductOfficeCountiesLasted
Apr 25, 7:17 PM CDTMesoscale DiscussionSPCAppanoose, Davis, Wapello, Wayne58 min
Apr 25, 9:23 PM CDTMesoscale DiscussionSPCDavis, Des Moines, Henry, Lee, Van Buren67 min
Apr 25, 10:09 PM CDTSevere Thunderstorm WatchSPCFremont, Page6 hr
Apr 26, 9:18 AM CDTMesoscale DiscussionSPCAudubon, Crawford, Harrison, Mills, Monona, Pottawattamie and 2 more27 min
Apr 26, 9:34 AM CDTSevere Thunderstorm WatchSPCAudubon, Buena Vista, Calhoun, Carroll, Cass, Cherokee and 29 more6 hr
Apr 26, 12:48 PM CDTTornado WatchSPCAdair, Adams, Audubon, Boone, Butler, Calhoun and 33 more4 hr
Apr 26, 2:41 PM CDTMesoscale DiscussionSPCAdair, Adams, Audubon, Boone, Buena Vista, Calhoun and 35 more3 hr
Apr 26, 5:02 PM CDTTornado WatchSPCAdair, Adams, Allamakee, Appanoose, Benton, Black Hawk and 41 more6 hr
Apr 26, 5:14 PM CDTMesoscale DiscussionSPCClayton, Delaware, Dubuque, Jackson61 min
Apr 26, 6:14 PM CDTMesoscale DiscussionSPCAdams, Appanoose, Benton, Black Hawk, Bremer, Buchanan and 40 more61 min
Apr 26, 2:10 AM CDTMesoscale DiscussionSPCAndrew, Atchison, Bates, Buchanan, Caldwell, Carroll and 23 more95 min
Apr 26, 12:27 PM CDTMesoscale DiscussionSPCGage, Jefferson, Johnson, Nemaha, Otoe, Pawnee and 1 more2 hr

Nearby

Mesoscale Discussions in Iowa, 2009Mesoscale Discussions in Nebraska, 2009Mesoscale Discussions in Missouri, 2009Every mesoscale discussion in 2009

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.