Alert archive / Nebraska / Mesoscale Discussions in 2012

Mesoscale Discussion 708

May 4, 201240 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at May 4, 2012, 10:55 PM CDT for 40 counties in Nebraska. It was in force for 35 min.

The area

The outline as issued.

The facts

Issued: May 4, 2012, 10:55 PM CDT (03:55 UTC)
Expired: May 4, 2012, 11:30 PM CDT
In force: 35 min
Issued by: the Storm Prediction Center

All 40 counties

Adams County, NE, Antelope County, NE, Boone County, NE, Buffalo County, NE, Burt County, NE, Butler County, NE, Cass County, NE, Clay County, NE, Colfax County, NE, Cuming County, NE, Dodge County, NE, Douglas County, NE, Fillmore County, NE, Garfield County, NE, Greeley County, NE, Hall County, NE, Hamilton County, NE, Howard County, NE, Kearney County, NE, Lancaster County, NE, Madison County, NE, Merrick County, NE, Nance County, NE, Otoe County, NE, Phelps County, NE, Pierce County, NE, Platte County, NE, Polk County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Sherman County, NE, Stanton County, NE, Thurston County, NE, Valley County, NE, Washington County, NE, Wayne County, NE, Wheeler County, NE, York County, NE

The radar

The Omaha radar (KOAX), 105 km from the middle of the area, began a volume at 03:57 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.

Severe Thunderstorm Watch 244May 4, 11:05 PM CDT

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 3.9 hours before the alert went out and 104 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: 2635 J/kg
Mixed-layer CIN: -14 J/kg
Mixed-layer LCL: 1505 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 71 m²/s²
0-3 km storm-relative helicity: 173 m²/s²
Significant tornado parameter: 0.6
Supercell composite: 8.5

Open this sounding in Storm Lab

The text

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

827 
ACUS11 KWNS 050356
SWOMCD
SPC MCD 050355
IAZ000-NEZ000-050430-

MESOSCALE DISCUSSION 0708
NWS STORM PREDICTION CENTER NORMAN OK
1055 PM CDT FRI MAY 04 2012

AREAS AFFECTED...PARTS OF CENTRAL AND ERN NEB

CONCERNING...SEVERE THUNDERSTORM WATCH 241...

VALID 050355Z - 050430Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 241
CONTINUES.

SUMMARY...A NEW WW WILL COORDINATED SOON TO REPLACE WW 241 AND THE
ONGOING SVR THREAT ACROSS A PART OF THE LOCALLY EXTENDED PORTION OF
WW 239.

DISCUSSION...STRONG TO SVR TSTMS CONTINUE TO DEVELOP ACROSS CENTRAL
AND NERN-ERN NEB...WITHIN A WAA REGIME N OF AN OLD OUTFLOW BOUNDARY
THAT EXTENDED GENERALLY E-W FROM EAST CENTRAL TO CENTRAL NEB.
RESIDUAL MODERATE INSTABILITY AND EFFECTIVE BULK SHEAR OF 40-50 KT
ARE MORE THAN SUFFICIENT TO SUSTAIN STRONG TO SEVERE STORMS FOR
SEVERAL MORE HOURS INTO THE EARLY OVERNIGHT PERIOD.

..PETERS.. 05/05/2012

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

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

LAT...LON   40599580 40329817 40409956 41569959 42129915 42279856
            42419704 42279634 41789612 40599580

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 4, 9:54 PM CDT	Mesoscale Discussion	SPC	Adams, Antelope, Boone, Buffalo, Burt, Butler and 42 more	96 min
May 4, 11:00 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Boone, Buffalo, Burt, Butler, Cass and 34 more	3 hr
May 5, 2:09 PM CDT	Mesoscale Discussion	SPC	Antelope, Boone, Burt, Butler, Cedar, Colfax and 22 more	96 min
May 5, 3:52 PM CDT	Mesoscale Discussion	SPC	Antelope, Boone, Cedar, Cuming, Dakota, Dixon and 11 more	83 min
May 5, 5:31 PM CDT	Tornado Watch	SPC	Antelope, Boone, Cedar, Custer, Dakota, Dawson and 15 more	5 hr
May 5, 6:21 PM CDT	Mesoscale Discussion	SPC	Boyd, Brown, Keya Paha, Rock, Thomas	84 min
May 5, 6:44 PM CDT	Mesoscale Discussion	SPC	Banner, Cheyenne, Kimball	61 min
May 5, 6:46 PM CDT	Severe Thunderstorm Watch	SPC	Arthur, Blaine, Boyd, Brown, Cherry, Deuel and 10 more	6 hr

Nearby

Mesoscale Discussions in Nebraska, 2012 Every 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.