Alert archive / Nebraska / Mesoscale Discussions in 2011

Mesoscale Discussion 2013

August 18, 20114 states

The Storm Prediction Center issued this mesoscale discussion at Aug 18, 2011, 9:52 PM CDT for 4 states. It was in force for 53 min.

The area

The outline as issued.

The facts

Issued
Aug 18, 2011, 9:52 PM CDT (02:52 UTC)
Expired
Aug 18, 2011, 10:45 PM CDT
In force
53 min
Issued by
the Storm Prediction Center
All 42 counties

Fremont County, IA, Page County, IA, Brown County, KS, Doniphan County, KS, Andrew County, MO, Atchison County, MO, Daviess County, MO, DeKalb County, MO, Gentry County, MO, Harrison County, MO, Holt County, MO, Nodaway County, MO, Worth County, MO, Boone County, NE, Butler County, NE, Cass County, NE, Clay County, NE, Colfax County, NE, Fillmore County, NE, Gage County, NE, Greeley County, NE, Hall County, NE, Hamilton County, NE, Howard County, NE, Jefferson County, NE, Johnson County, NE, Lancaster County, NE, Madison County, NE, Merrick County, NE, Nance County, NE, Nemaha County, NE, Otoe County, NE, Pawnee County, NE, Platte County, NE, Polk County, NE, Richardson County, NE, Saline County, NE, Saunders County, NE, Seward County, NE, Stanton County, NE, Thayer County, NE, York County, NE

The radar

The Omaha radar (KOAX), 72 km from the middle of the area, began a volume at 02:55 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, 2.9 hours before the alert went out and 72 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 00:00Z on 2011-08-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1385 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 00:00Z on 2011-08-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 289 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
1385 J/kg
Mixed-layer CIN
-135 J/kg
Mixed-layer LCL
582 m above ground
0-6 km bulk shear
66 kt
0-1 km storm-relative helicity
289 m²/s²
0-3 km storm-relative helicity
636 m²/s²
Significant tornado parameter
0.0
Supercell composite
47.4

Open this sounding in Storm Lab

The text

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

351 
ACUS11 KWNS 190252
SWOMCD
SPC MCD 190252 
MOZ000-IAZ000-KSZ000-NEZ000-190345-

MESOSCALE DISCUSSION 2013
NWS STORM PREDICTION CENTER NORMAN OK
0952 PM CDT THU AUG 18 2011

AREAS AFFECTED...CENTRAL/ERN NEB...SWRN IA...NWRN MO

CONCERNING...TORNADO WATCH 787...

VALID 190252Z - 190345Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 787 CONTINUES.

...ERN HALF OF WW 787...
THE GREATEST SEVERE WEATHER THREAT WITHIN WW 787 IS CONFINED TO EAST
CENTRAL AND SERN NEB INTO FAR SWRN IA AND NWRN MO.  AT
0240Z...REGIONAL RADAR IMAGERY SHOWED A BOWING STRUCTURE MOVING SWD
THROUGH THE SRN EXTENT OF THIS WATCH...APPROACHING THE NRN EXTENT OF
WW 788.  MEANWHILE...THE WRN FLANK OF THE BOW OVER SERN NEB HAS
BECOME MORE REMOVED FROM THE OUTFLOW BOUNDARY WHICH EXTENDED 40
MILES TO THE WEST OF THE STORMS.  THIS SUGGESTS THE TORNADO THREAT
WILL CONTINUE TO DIMINISH GIVEN STORMS BECOMING MORE REMOVED FROM
THE INFLUENCE OF SURFACE BASED PARCELS.

A 30-35 KT SLY LLJ EXTENDING FROM SRN/ERN KS INTO THE LEADING EXTENT
OF THE BOW WILL MAINTAIN MASS FLUX/WAA AND AN INFLOW OF MODERATE
INSTABILITY TO SUSTAIN THE SWD PROPAGATION OF THIS MCS.

...WRN HALF OF WW 787...
COUNTIES IN THE WRN EXTENT OF WW 787 /LBF CWA/ HAVE BEEN REMOVED
FROM THIS WATCH GIVEN AN INCREASING CAP PER LOSS OF DAYTIME HEATING
AND THE MIDLEVEL INVERSION EVIDENT ON THE 00Z LBF SOUNDING
INHIBITING TSTM DEVELOPMENT.

..PETERS.. 08/19/2011

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

ATTN...WFO...DMX...EAX...OAX...TOP...GID...LBF...

LAT...LON   39889355 39709424 39899640 39999773 40739875 41709870
            42139817 42069710 41439684 40889587 40739549 40919494
            40579490 40579380 39889355

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 18, 8:29 PM CDTMesoscale DiscussionSPCAdams, Cass, Fremont, Mills, Montgomery, Page and 2 more61 min
Aug 18, 8:09 PM CDTSevere Thunderstorm WatchSPCAnderson, Atchison, Brown, Coffey, Doniphan, Douglas and 18 more7 hr
Aug 18, 11:46 PM CDTMesoscale DiscussionSPCAllen, Anderson, Atchison, Bourbon, Brown, Chase and 28 more59 min
Aug 19, 12:02 AM CDTSevere Thunderstorm WatchSPCAllen, Bourbon, Cherokee, Crawford, Labette, Montgomery and 3 more5 hr
Aug 19, 1:38 AM CDTMesoscale DiscussionSPCAllen, Bourbon, Cherokee, Crawford, Labette, Montgomery and 2 more67 min
Aug 19, 3:42 PM CDTMesoscale DiscussionSPCBarton, Clark, Comanche, Edwards, Ellis, Finney and 26 more63 min
Aug 19, 1:08 AM CDTSevere Thunderstorm WatchSPCCole, Crawford, Franklin, Gasconade, Iron, Madison and 5 more4 hr
Aug 19, 4:08 AM CDTMesoscale DiscussionSPCBarry, Camden, Christian, Crawford, Dallas, Dent and 22 more67 min
Aug 19, 5:01 PM CDTMesoscale DiscussionSPCBanner, Cheyenne, Kimball, Scotts Bluff, Sioux59 min

Nearby

Mesoscale Discussions in Nebraska, 2011Mesoscale Discussions in Missouri, 2011Mesoscale Discussions in Iowa, 2011Every 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.