Alert archive / Nebraska / Mesoscale Discussions in 2012

Mesoscale Discussion 390

March 30, 201213 counties in Iowa; 28 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Mar 30, 2012, 3:20 PM CDT for 13 counties in Iowa; 28 counties in Nebraska. It was in force for 85 min.

The area

The outline as issued.

The facts

Issued: Mar 30, 2012, 3:20 PM CDT (20:20 UTC)
Expired: Mar 30, 2012, 4:45 PM CDT
In force: 85 min
Issued by: the Storm Prediction Center

All 41 counties

Adams County, IA, Audubon County, IA, Cass County, IA, Crawford County, IA, Fremont County, IA, Harrison County, IA, Mills County, IA, Monona County, IA, Montgomery County, IA, Page County, IA, Pottawattamie County, IA, Shelby County, IA, Woodbury County, IA, Antelope County, NE, Boone County, NE, Burt County, NE, Butler County, NE, Cass County, NE, Cedar County, NE, Colfax County, NE, Cuming County, NE, Dakota County, NE, Dixon County, NE, Dodge County, NE, Douglas County, NE, Knox County, NE, Lancaster County, NE, Madison County, NE, Nance County, NE, Otoe County, NE, Pierce County, NE, Platte County, NE, Polk County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Stanton County, NE, Thurston County, NE, Washington County, NE, Wayne County, NE, Wheeler County, NE

The radar

The Omaha radar (KOAX), 30 km from the middle of the area, began a volume at 20:22 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, 8.3 hours before the alert went out and 30 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1139 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: -100 m²/s²
0-3 km storm-relative helicity: -119 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.

874 
ACUS11 KWNS 302020
SWOMCD
SPC MCD 302020 
IAZ000-NEZ000-SDZ000-302145-

MESOSCALE DISCUSSION 0390
NWS STORM PREDICTION CENTER NORMAN OK
0320 PM CDT FRI MAR 30 2012

AREAS AFFECTED...ERN NEB...WRN IA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 302020Z - 302145Z

ISOLATED THUNDERSTORMS ARE FORECAST TO DEVELOP ACROSS ERN NEB AND
WRN IA THIS AFTERNOON AND EVENING. A SVR STORM WILL BE
POSSIBLE...BUT THE THREAT IS TOO MARGINAL FOR A WW.

MESOANALYSIS AT 19-20Z SHOWS A BAROCLINIC ZONE COLLOCATED WITH
CONFLUENT SURFACE STREAMLINES EXTENDING SEWD OUT OF SRN SD TOWARD
OMA AND INTO NRN MO. MEANWHILE...A MIDLEVEL IMPULSE IS MOVING SEWD
TOWARD ERN NEB/WRN IA. STEEP LOW-LEVEL LAPSE RATES INDICATIVE OF
ROBUST BOUNDARY LAYER DESTABILIZATION ARE DEVELOPING EWD TOWARD THE
SURFACE BOUNDARY. THIS DESTABILIZATION COMBINED WITH ASCENT
ASSOCIATED WITH THE MIDLEVEL IMPULSE APPEAR TO BE AIDING IN SURFACE
BASED CUMULUS DEVELOPMENT INVOF BUB AND ONL...WHICH MAY
DEEPEN/EVOLVE INTO ISOLATED THUNDERSTORMS AS RELATIVELY DEEPER
MOISTER IS ENCOUNTERED OVER ERN NEB. COMBINATION OF STEEP MIDLEVEL
LAPSE RATES FROM 7-8 C/KM...SURFACE TEMPERATURES IN THE MID 70S AND
DEWPOINTS IN THE 40S TO LOW 50S WILL AID IN MLCAPE VALUES NEAR 500
J/KG. GIVEN THE PRESENCE OF LOW-LEVEL SWLYS VEERING TO W-NWLY IN THE
MIDLEVELS...VERTICAL SHEAR PROFILES...CHARACTERIZED BY 0-6 KM BULK
WIND DIFFERENCE FROM 30-50 KT...WILL SUPPORT ORGANIZED THUNDERSTORM
DEVELOPMENT INCLUDING SUPERCELLS. THESE STORMS WILL BE DRIVEN SEWD
ALONG THE BAROCLINIC ZONE COINCIDENT WITH THE PASSAGE OF THE
MIDLEVEL IMPULSE...AND POSE A THREAT FOR ISOLATED DAMAGING WIND
GUSTS AND LARGE HAIL. HOWEVER...GIVEN ONLY MARGINAL MOISTURE AND
BUOYANCY...THE SVR THREAT SHOULD BE NARROWLY CONFINED TO THE
BAROCLINIC ZONE...AND BE TOO LIMITED FOR A WW.

..GARNER.. 03/30/2012

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

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

LAT...LON   40609564 40679673 41419833 42269874 42859837 42599652
            41929479 40889452 40609564

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 29, 7:55 PM CDT	Mesoscale Discussion	SPC	Adair, Adams, Appanoose, Cass, Clarke, Dallas and 12 more	65 min
Mar 29, 8:30 PM CDT	Severe Thunderstorm Watch	SPC	Adair, Adams, Appanoose, Cass, Clarke, Decatur and 9 more	6 hr
Mar 29, 9:51 PM CDT	Mesoscale Discussion	SPC	Fremont, Mills, Montgomery, Page	54 min
Mar 29, 11:50 PM CDT	Mesoscale Discussion	SPC	Appanoose, Clarke, Decatur, Lucas, Madison, Mahaska and 6 more	55 min

Nearby

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