Alert archive / Nebraska / Mesoscale Discussions in 2012

Mesoscale Discussion 716

May 5, 201214 counties in Iowa; 17 counties in Nebraska; 4 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at May 5, 2012, 3:52 PM CDT for 14 counties in Iowa; 17 counties in Nebraska; 4 counties in South Dakota. It was in force for 83 min.

The area

The outline as issued.

The facts

Issued
May 5, 2012, 3:52 PM CDT (20:52 UTC)
Expired
May 5, 2012, 5:15 PM CDT
In force
83 min
Issued by
the Storm Prediction Center
Chance of a watch
95%
All 35 counties

Buena Vista County, IA, Calhoun County, IA, Carroll County, IA, Cherokee County, IA, Clay County, IA, Crawford County, IA, Ida County, IA, Monona County, IA, O'Brien County, IA, Plymouth County, IA, Pocahontas County, IA, Sac County, IA, Sioux County, IA, Woodbury County, IA, Antelope County, NE, Boone County, NE, Cedar County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Garfield County, NE, Greeley County, NE, Knox County, NE, Madison County, NE, Pierce County, NE, Sherman County, NE, Stanton County, NE, Thurston County, NE, Valley County, NE, Wayne County, NE, Wheeler County, NE, Clay County, SD, Lincoln County, SD, Union County, SD, Yankton County, SD

The radar

The Omaha radar (KOAX), 110 km from the middle of the area, began a volume at 20:55 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, 8.9 hours before the alert went out and 109 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 2012-05-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2817 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 2012-05-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 65 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
2817 J/kg
Mixed-layer CIN
-106 J/kg
Mixed-layer LCL
783 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
65 m²/s²
0-3 km storm-relative helicity
21 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

043 
ACUS11 KWNS 052052
SWOMCD
SPC MCD 052052 
IAZ000-NEZ000-SDZ000-052215-

MESOSCALE DISCUSSION 0716
NWS STORM PREDICTION CENTER NORMAN OK
0352 PM CDT SAT MAY 05 2012

AREAS AFFECTED...CNTRL-NERN NEB / SERN SD / NWRN IA

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY 

VALID 052052Z - 052215Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...SUPERCELLS CAPABLE OF TORNADOES...VERY LARGE HAIL...AND
DAMAGING WIND GUSTS ARE EXPECTED TO DEVELOP PRIOR TO 00Z...REQUIRING
A TORNADO WATCH.

DISCUSSION...20Z SURFACE ANALYSIS SHOWED A SURFACE LOW W OF MCK WITH
AN ASSOCIATED STATIONARY BOUNDARY EXTENDING NEWD TO N OF OFK AND SUX
BEFORE CURVING SEWD THROUGH CNTRL IA.  AIR MASS ALONG AND S OF THIS
BOUNDARY HAS WARMED INTO THE UPPER 80S-LOWER 90S AND WHEN COUPLED
WITH DEWPOINTS IN THE MID-UPPER 60S...IS RESULTING IN MLCAPE VALUES
OF 3000-4000 J/KG AND A WEAKENING CAP.  THOUGH LOW-LEVEL WAA
PERSISTS...MIDLEVEL HEIGHTS APPEAR TO BE STILL SLIGHTLY RISING AHEAD
OF NRN ROCKIES UPPER TROUGH.  AS SUCH...IT NOW APPEARS THAT STORM
INITIATION MAY BE DELAYED TO CLOSER TO 00Z WHEN CONVERGENCE
INCREASES IN THE EXIT REGION OF A STRENGTHENING LLJ.

PRONOUNCED VEERING OF WINDS WITH HEIGHT AND STRENGTHENING LOW AND
DEEP-LAYER SHEAR WILL SUPPORT THE RAPID EVOLUTION OF STORMS INTO
SUPERCELLS WITH AN ASSOCIATED THREAT FOR TORNADOES...VERY LARGE HAIL
AND DAMAGING WINDS.

A TORNADO WATCH WILL BE REQUIRED PRIOR TO 00Z.

..MEAD.. 05/05/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DMX...FSD...OAX...GID...LBF...

LAT...LON   41249982 42219894 43039777 43359680 43329541 42789444
            42339413 42039440 41989545 41919662 41379858 41069937
            41099965 41249982

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 4, 8:30 PM CDTMesoscale DiscussionSPCAllamakee, Benton, Black Hawk, Bremer, Buchanan, Butler and 10 more60 min
May 4, 9:54 PM CDTMesoscale DiscussionSPCBuena Vista, Cherokee, Crawford, Harrison, Ida, Monona and 5 more96 min
May 5, 6:49 AM CDTSevere Thunderstorm WatchSPCCherokee, Lyon, O'Brien, Osceola, Plymouth, Sioux7 hr
May 5, 11:38 AM CDTSevere Thunderstorm WatchSPCAllamakee, Cerro Gordo, Chickasaw, Clayton, Emmet, Fayette and 8 more6 hr
May 5, 2:09 PM CDTMesoscale DiscussionSPCBuena Vista, Calhoun, Carroll, Cherokee, Clay, Crawford and 8 more96 min
May 5, 2:58 PM CDTMesoscale DiscussionSPCAllamakee, Dickinson, Emmet, Howard, Kossuth, Mitchell and 3 more62 min
May 5, 4:56 PM CDTMesoscale DiscussionSPCBremer, Buchanan, Clayton, Delaware, Dubuque, Fayette and 1 more94 min
May 5, 5:31 PM CDTTornado WatchSPCPlymouth, Sioux, Woodbury5 hr
May 5, 6:46 PM CDTSevere Thunderstorm WatchSPCLyon6 hr
May 4, 10:55 PM CDTMesoscale DiscussionSPCAdams, Antelope, Boone, Buffalo, Burt, Butler and 34 more35 min
May 4, 11:00 PM CDTSevere Thunderstorm WatchSPCAdams, Boone, Buffalo, Burt, Butler, Cass and 34 more3 hr
May 5, 6:21 PM CDTMesoscale DiscussionSPCBoyd, Brown, Keya Paha, Rock, Thomas84 min
May 5, 6:44 PM CDTMesoscale DiscussionSPCBanner, Cheyenne, Kimball61 min
May 5, 3:06 AM CDTMesoscale DiscussionSPCCuster, Fall River, Haakon, Hughes, Hyde, Jackson and 9 more84 min
May 5, 3:19 AM CDTSevere Thunderstorm WatchSPCBennett, Buffalo, Butte, Custer, Dewey, Fall River and 17 more9 hr
May 5, 9:50 AM CDTMesoscale DiscussionSPCAurora, Beadle, Brookings, Brule, Buffalo, Davison and 13 more55 min

Nearby

Mesoscale Discussions in Nebraska, 2012Mesoscale Discussions in Iowa, 2012Mesoscale Discussions in South Dakota, 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.