Alert archive / Nebraska / Mesoscale Discussions in 2012

Mesoscale Discussion 528

April 14, 201211 counties in Iowa; 28 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Apr 14, 2012, 2:15 PM CDT for 11 counties in Iowa; 28 counties in Nebraska. It was in force for 90 min.

The area

The outline as issued.

The facts

Issued
Apr 14, 2012, 2:15 PM CDT (19:15 UTC)
Expired
Apr 14, 2012, 3:45 PM CDT
In force
90 min
Issued by
the Storm Prediction Center
All 39 counties

Adams County, IA, Audubon County, IA, Cass 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, Adams County, NE, Burt County, NE, Butler County, NE, Cass County, NE, Clay County, NE, Colfax County, NE, Dodge County, NE, Douglas County, NE, Fillmore County, NE, Franklin County, NE, Gage County, NE, Hamilton County, NE, Jefferson County, NE, Johnson County, NE, Lancaster County, NE, Nemaha County, NE, Nuckolls County, NE, Otoe County, NE, Pawnee County, NE, Polk County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Thayer County, NE, Washington County, NE, Webster County, NE, York County, NE

The radar

The Omaha radar (KOAX), 8 km from the middle of the area, began a volume at 19:18 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, 7.3 hours before the alert went out and 7 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 2012-04-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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 2012-04-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 2 square meters per square second.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1847 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
2 m²/s²
0-3 km storm-relative helicity
89 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.

571 
ACUS11 KWNS 141916
SWOMCD
SPC MCD 141915
IAZ000-MOZ000-NEZ000-142045-

MESOSCALE DISCUSSION 0528
NWS STORM PREDICTION CENTER NORMAN OK
0215 PM CDT SAT APR 14 2012

AREAS AFFECTED...SRN THROUGH ERN NEB AND SWRN IA

CONCERNING...TORNADO WATCH 165...

VALID 141915Z - 142045Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 165 CONTINUES.

THREAT FOR TORNADOES...A FEW OF WHICH COULD BE STRONG...AND VERY
LARGE HAIL WILL PERSIST INTO THE EVENING OVER ERN AND SRN NEB.
SEVERE THREAT IS BEGINNING TO SHIFT INTO SWRN IA...AND WW MAY NEED
TO BE EXTENDED FARTHER EAST OR ANOTHER WW MIGHT BE ISSUED.

PRIMARY TORNADO THREAT APPEARS TO BE EVOLVING OVER EXTREME SRN NEB
NEXT COUPLE HOURS...AS SFC BASED SUPERCELLS LIFT NORTH INTO NEB
COUNTIES BORDERING THE KS STATE LINE. LOW LEVEL HODOGRAPHS WILL
CONTINUE TO INCREASE AS THE LLJ SHIFTS NWD DURING THE EVENING. THE
SUPERCELL IN NERN NEB HAS BEEN MAINLY A HAIL PRODUCER...BUT MAY NOT
BE FAR FROM SURFACE BASED SUGGESTING A TORNADO CANNOT BE RULED OUT.

OTHER NEAR SFC BASED STORMS ARE DEVELOPING FARTHER EAST INTO SWRN
IA. THIS ACTIVITY IS EAST OF THETA-E AXIS AND PRIMARY LLJ AND IS
ALSO CLOSE TO THE ERN EDGE OF THE STRONGER SFC BASED INSTABILITY.
ENVIRONMENTAL PARAMETERS SHOULD GRADUALLY BECOME MORE FAVORABLE FOR
TORNADOES INTO THE EVENING AS THE LLJ DEVELOPS NEWD AND BOUNDARY
LAYER MOISTURE INCREASES.

..DIAL.. 04/14/2012

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

ATTN...WFO...DMX...EAX...OAX...GID...

LAT...LON   42159628 41819460 41069442 40079617 40109913 41439774
            42159628

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 14, 12:00 PM CDTTornado Watch PDSSPCFremont, Harrison, Mills, Monona, Montgomery, Page and 2 more7 hr
Apr 14, 2:56 PM CDTTornado WatchSPCAdair, Adams, Appanoose, Audubon, Cass, Clarke and 14 more2 hr
Apr 14, 4:47 PM CDTMesoscale DiscussionSPCAdair, Adams, Appanoose, Cass, Clarke, Dallas and 17 more58 min
Apr 14, 5:00 PM CDTTornado WatchSPCAdair, Adams, Appanoose, Audubon, Cass, Clarke and 18 more7 hr
Apr 14, 6:57 PM CDTMesoscale DiscussionSPCAdair, Adams, Appanoose, Audubon, Cass, Clarke and 23 more63 min
Apr 14, 10:43 AM CDTTornado Watch PDSSPCHitchcock, Red Willow7 hr
Apr 14, 11:27 AM CDTMesoscale DiscussionSPCAdams, Buffalo, Clay, Fillmore, Franklin, Furnas and 19 more2 hr
Apr 14, 1:41 PM CDTMesoscale DiscussionSPCArthur, Custer, Dawson, Frontier, Garden, Grant and 9 more2 hr
Apr 14, 2:33 PM CDTTornado WatchSPCBlaine, Custer, Frontier, Garfield, Hayes, Holt and 7 more8 hr
Apr 14, 5:24 PM CDTTornado Watch PDSSPCHitchcock, Red Willow9 hr
Apr 14, 6:27 PM CDTTornado Watch PDSSPCAdams, Buffalo, Cass, Clay, Dawson, Fillmore and 30 more9 hr

Nearby

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