Alert archive / Nebraska / Mesoscale Discussions in 2012

Mesoscale Discussion 929

May 27, 20124 states

The Storm Prediction Center issued this mesoscale discussion at May 27, 2012, 6:55 PM CDT for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
May 27, 2012, 6:55 PM CDT (23:55 UTC)
Expired
May 27, 2012, 9:00 PM CDT
In force
2 hr
Issued by
the Storm Prediction Center
All 63 counties

Cherokee County, IA, Clay County, IA, Dickinson County, IA, Emmet County, IA, Ida County, IA, Lyon County, IA, Monona County, IA, O'Brien County, IA, Osceola County, IA, Plymouth County, IA, Sioux County, IA, Woodbury County, IA, Blue Earth County, MN, Cottonwood County, MN, Jackson County, MN, Martin County, MN, Murray County, MN, Nobles County, MN, Pipestone County, MN, Rock County, MN, Watonwan County, MN, Adams County, NE, Antelope County, NE, Boone County, NE, Buffalo County, NE, Burt County, NE, Butler County, NE, Cedar County, NE, Clay County, NE, Colfax County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Dodge County, NE, Fillmore County, NE, Greeley County, NE, Hall County, NE, Hamilton County, NE, Howard County, NE, Kearney County, NE, Knox County, NE, Madison County, NE, Merrick County, NE, Nance County, NE, Phelps County, NE, Pierce County, NE, Platte County, NE, Polk County, NE, Saunders County, NE, Seward County, NE, Sherman County, NE, Stanton County, NE, Thayer County, NE, Thurston County, NE, Wayne County, NE, Wheeler County, NE, York County, NE, Clay County, SD, Lincoln County, SD, Minnehaha County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Omaha radar (KOAX), 103 km from the middle of the area, began a volume at 23:56 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 nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 11.9 hours before the alert went out and 103 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 2012-05-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1034 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 2012-05-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 222 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
1034 J/kg
Mixed-layer CIN
-295 J/kg
Mixed-layer LCL
1208 m above ground
0-6 km bulk shear
34 kt
0-1 km storm-relative helicity
222 m²/s²
0-3 km storm-relative helicity
245 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

222 
ACUS11 KWNS 272355
SWOMCD
SPC MCD 272355 
MNZ000-IAZ000-NEZ000-SDZ000-280200-

MESOSCALE DISCUSSION 0929
NWS STORM PREDICTION CENTER NORMAN OK
0655 PM CDT SUN MAY 27 2012

AREAS AFFECTED...ERN NEB...SERN SD...SWRN MN AND NWRN IA

CONCERNING...SEVERE THUNDERSTORM WATCH 304...

VALID 272355Z - 280200Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 304
CONTINUES.

SUMMARY...STORMS DEVELOPING FROM ERN NEB...SERN SD...NWRN IA AND
SWRN MN WILL CONTINUE TO POSE A PRIMARY THREAT FOR LARGE
HAIL...DAMAGING WIND AS WELL AS VERY HEAVY RAIN THIS EVENING. A
COUPLE OF TORNADOES ALSO CANNOT BE RULED OUT.

DISCUSSION...STORMS WILL CONTINUE ALONG AND AHEAD OF SLOW MOVING
COLD FRONT FROM ERN NEB INTO SWRN MN THIS EVENING. STORMS ARE
DEVELOPING WITHIN 1500-2000 J/KG MLCAPE...STEEP LAPSE RATES AND
EFFECTIVE DEEP SHEAR OF 40-50 KT SUPPORTIVE OF ORGANIZED STORMS
INCLUDING SUPERCELLS AND BOWING SEGMENTS. ACTIVITY WILL REMAIN
CAPABLE OF MOSTLY LARGE HAIL AND DAMAGING WIND. LOW-LEVEL
TEMPERATURE-DEWPOINT SPREADS OF 25-30F AND MODEST LOW LEVEL SHEAR
SHOULD MITIGATE OVERALL TORNADO POTENTIAL...BUT A COUPLE CANNOT BE
RULED OUT. WITH UPPER TROUGH AXIS STILL TO THE WEST...DEEP LAYER
WINDS NEARLY PARALLEL TO THE BAROCLINIC ZONE WILL PROMOTE NEWD
TRAINING OF CELLS...AND WITH TIME STORMS SHOULD TEND TO CONGEAL INTO
MIXED MODES WITH LINE SEGMENTS WITH EMBEDDED SUPERCELLS. THESE
FACTORS WILL PROMOTE VERY HEAVY RAIN IN ADDITION TO SEVERE WEATHER
ALONG THE AXIS OF TRAINING.

..DIAL.. 05/27/2012

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

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

LAT...LON   40309961 42649825 44399602 44029397 41189662 40169760
            40309961

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 27, 2:58 PM CDTMesoscale DiscussionSPCBuena Vista, Cherokee, Clay, Crawford, Dickinson, Emmet and 13 more62 min
May 27, 3:42 PM CDTSevere Thunderstorm WatchSPCBuena Vista, Cherokee, Clay, Crawford, Dickinson, Emmet and 12 more8 hr
May 26, 7:56 PM CDTMesoscale DiscussionSPCAitkin, Carlton, Crow Wing, Itasca, Pine2 hr
May 26, 11:57 PM CDTMesoscale DiscussionSPCBecker, Benton, Clay, Crow Wing, Douglas, Grant and 12 more93 min
May 27, 3:49 PM CDTMesoscale DiscussionSPCAnoka, Benton, Chisago, Crow Wing, Douglas, Grant and 19 more56 min
May 27, 6:08 PM CDTSevere Thunderstorm WatchSPCAitkin, Anoka, Benton, Blue Earth, Brown, Carver and 40 more7 hr
May 26, 9:07 PM CDTMesoscale DiscussionSPCCherry, Keya Paha53 min

Nearby

Mesoscale Discussions in Nebraska, 2012Mesoscale Discussions in Iowa, 2012Mesoscale Discussions in Minnesota, 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.