Alert archive / Nebraska / Mesoscale Discussions in 2011

Mesoscale Discussion 769

May 12, 20114 states

The Storm Prediction Center issued this mesoscale discussion at May 12, 2011, 9:16 PM CDT for 4 states. It was in force for 59 min.

The area

The outline as issued.

The facts

Issued: May 12, 2011, 9:16 PM CDT (02:16 UTC)
Expired: May 12, 2011, 10:15 PM CDT
In force: 59 min
Issued by: the Storm Prediction Center

All 22 counties

Fremont County, IA, Harrison County, IA, Mills County, IA, Page County, IA, Pottawattamie County, IA, Brown County, KS, Atchison County, MO, Butler County, NE, Cass County, NE, Dodge County, NE, Douglas County, NE, Johnson County, NE, Lancaster County, NE, Nemaha County, NE, Otoe County, NE, Pawnee County, NE, Polk County, NE, Richardson County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Washington County, NE

The radar

The Omaha radar (KOAX), 60 km from the middle of the area, began a volume at 02:19 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 00:00Z, 2.3 hours before the alert went out and 60 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1648 J/kg
Mixed-layer CIN: -45 J/kg
Mixed-layer LCL: 900 m above ground
0-6 km bulk shear: 17 kt
0-1 km storm-relative helicity: 19 m²/s²
0-3 km storm-relative helicity: 50 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 0.6

Open this sounding in Storm Lab

The text

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

873 
ACUS11 KWNS 130217
SWOMCD
SPC MCD 130216
MOZ000-IAZ000-NEZ000-KSZ000-130315-

MESOSCALE DISCUSSION 0769
NWS STORM PREDICTION CENTER NORMAN OK
0916 PM CDT THU MAY 12 2011

AREAS AFFECTED...EASTERN NEB/WESTERN IA INTO EXTREME NORTHEAST
KS/NORTHWEST MO

CONCERNING...TORNADO WATCH 292...

VALID 130216Z - 130315Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 292 CONTINUES.

ISOLATED TORNADO POTENTIAL IS EXPECTED TO CONTINUE TO WANE ACROSS
EASTERN NEB/FAR WESTERN IA...WITH SEVERE HAIL REMAINING A
POSSIBILITY. GIVEN THE 03Z SCHEDULED EXPIRATION OF WW 292...A LOCAL
WFO EXTENSION /OR PERHAPS A REPLACEMENT WATCH/ WILL NEED TO BE
CONSIDERED. ISOLATED SEVERE TSTM DEVELOPMENT CANNOT BE RULED OUT
INTO FAR NORTHEAST KS/FAR NORTHWEST MO.

STRONG/SEVERE TSTMS CONTINUE TO DEVELOP IN VICINITY OF AN EFFECTIVE
TRIPLE POINT/RELATIVELY NARROW CORRIDOR OF RESIDUAL HIGHER LOW LEVEL
THETA-E WITHIN AN AREA GENERALLY 50 MILES EITHER SIDE OF I-80 IN FAR
EASTERN NEB. THE 00Z OBSERVED RAOB FROM OMAHA REFLECTED A RATHER
POTENT THERMODYNAMIC ENVIRONMENT WITH RESPECT TO RELATIVELY
LOW-TOPPED STORMS /EQUILIBRIUM LEVEL AROUND 30K FT/...WITH MLCAPE OF
1700 J/KG AND MUCAPE OF 2600 J/KG. WHILE AMBIENT VERTICAL
VORTICITY/RESIDUAL UNSTABLE BOUNDARY LAYER WILL SUPPORT SOME TORNADO
THREAT IN THE SHORT TERM...A GRADUALLY COOLING/DECOUPLING BOUNDARY
LAYER IMPLY A WANING TORNADO THREAT THE REMAINDER OF THE EVENING.
THAT SAID...SEVERE HAIL POTENTIAL WILL PERSIST NONETHELESS...AND AN
EXTENSION OF WW 292 MAY BE WARRANTED BEYOND 03Z. FARTHER
SOUTHEAST...ADDITIONAL SEVERE DEVELOPMENT CANNOT BE RULED OUT ALONG
THE ARCING COLD FRONT/MERGING FRONTAL ZONE INTO FAR NORTHEAST
KS/NORTHWEST MO...AT LEAST IN AN ISOLATED SENSE.

..GUYER.. 05/13/2011

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

ATTN...WFO...EAX...OAX...TOP...GID...

LAT...LON   41069783 41629695 41779579 40589499 39719549 39669562
            41069783

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 12, 10:27 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Audubon, Black Hawk, Boone, Bremer and 31 more	63 min
May 12, 9:41 PM CDT	Mesoscale Discussion	SPC	Dent, Douglas, Howell, Oregon, Ozark, Shannon and 3 more	64 min
May 12, 10:03 PM CDT	Severe Thunderstorm Watch	SPC	Dent, Howell, Maries, Oregon, Phelps, Pulaski and 2 more	7 hr
May 12, 10:09 PM CDT	Mesoscale Discussion	SPC	Bollinger, Butler, Carter, Crawford, Dent, Dunklin and 18 more	66 min
May 13, 12:01 PM CDT	Mesoscale Discussion	SPC	Butler, Dunklin, Mississippi, New Madrid, Pemiscot, Ripley and 2 more	89 min
May 13, 12:31 PM CDT	Severe Thunderstorm Watch	SPC	Bollinger, Butler, Cape Girardeau, Carter, Dunklin, Mississippi and 6 more	6 hr
May 13, 2:44 PM CDT	Mesoscale Discussion	SPC	Dunklin, Mississippi, New Madrid, Pemiscot, Scott	2 hr
May 13, 4:40 PM CDT	Mesoscale Discussion	SPC	Lincoln, Saint Charles, Saint Louis, City of Saint Louis	95 min

Nearby

Mesoscale Discussions in Nebraska, 2011 Mesoscale Discussions in Iowa, 2011 Mesoscale Discussions in Kansas, 2011 Every mesoscale discussion in 2011

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.