Alert archive / Nebraska / Mesoscale Discussions in 2012

Mesoscale Discussion 171

February 28, 20126 counties in Iowa; Atchison County, Holt County, Nodaway County, Missouri; 21 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Feb 28, 2012, 8:23 PM CST for 6 counties in Iowa; Atchison County, Holt County, Nodaway County, Missouri; 21 counties in Nebraska. It was in force for 37 min.

The area

The outline as issued.

The facts

Issued: Feb 28, 2012, 8:23 PM CST (02:23 UTC)
Expired: Feb 28, 2012, 9:00 PM CST
In force: 37 min
Issued by: the Storm Prediction Center

All 30 counties

Fremont County, IA, Harrison County, IA, Mills County, IA, Montgomery County, IA, Page County, IA, Pottawattamie County, IA, Atchison County, MO, Holt County, MO, Nodaway County, MO, Burt County, NE, Butler County, NE, Cass County, NE, Colfax County, NE, Cuming County, NE, Dodge County, NE, Douglas County, NE, Gage County, NE, Jefferson County, NE, Johnson County, NE, Lancaster County, NE, Nemaha County, NE, Otoe County, NE, Pawnee County, NE, Richardson County, NE, Saline County, NE, Sarpy County, NE, Saunders County, NE, Seward County, NE, Stanton County, NE, Washington County, NE

The radar

The Omaha radar (KOAX), 36 km from the middle of the area, began a volume at 02:25 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, 2.4 hours before the alert went out and 36 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: 464 m above ground
0-6 km bulk shear: 63 kt
0-1 km storm-relative helicity: 519 m²/s²
0-3 km storm-relative helicity: 560 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.

754 
ACUS11 KWNS 290224
SWOMCD
SPC MCD 290223
IAZ000-MOZ000-NEZ000-290300-

MESOSCALE DISCUSSION 0171
NWS STORM PREDICTION CENTER NORMAN OK
0823 PM CST TUE FEB 28 2012

AREAS AFFECTED...ERN NEB...SWRN IA

CONCERNING...TORNADO WATCH 39...

VALID 290223Z - 290300Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 39 CONTINUES.

WW 39 IS SCHEDULED TO EXPIRE AT 03Z. TSTM CLUSTERS HAVE DEVELOPED
INTO ERN PORTIONS OF WW 39 AND DOWNSTREAM ALONG THE MO VALLEY.
DAMAGING WIND AND SEVERE HAIL POTENTIAL APPEARS MARGINAL...AS
ACTIVITY SHOULD BECOME INCREASINGLY ELEVATED WITH NERN EXTENT. A
REPLACEMENT WW IS NOT ANTICIPATED.

02Z SURFACE ANALYSIS PLACED A 994 MB CYCLONE AROUND 35 SE ONL WITH A
COLD FRONT EXTENDING SWD TO NEAR CNK...AND A WARM FRONT ARCING SEWD
ACROSS SWRN IA INTO NRN MO. ALTHOUGH THE AIR MASS HAS BEEN
DESTABILIZING IN THE WARM SECTOR ACROSS SERN NEB...MODIFIED 00Z TOP
RAOB WOULD SUGGEST THAT WEAKLY BUOYANT PARCELS ARE ROOTED ABOVE A
SHALLOW SURFACE STABLE LAYER. PRESENCE OF 45-50 KT S/SWLYS AT 1 KM
AGL PER AREA PROFILER AND VWP DATA MAY STILL SUPPORT A LOCALIZED
DAMAGING WIND RISK BEYOND 03Z. BUT THIS THREAT DOES NOT APPEAR
SUFFICIENT TO WARRANT AN ADDITIONAL WW.

..GRAMS.. 02/29/2012

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

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

LAT...LON   40159716 41109739 41689753 42039749 42079693 41959615
            41559520 40919477 40229482 40059519 40079680 40159716

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 28, 9:47 PM CST	Mesoscale Discussion	SPC	Bates, Buchanan, Caldwell, Carroll, Cass, Clay and 9 more	58 min
Feb 28, 10:07 PM CST	Severe Thunderstorm Watch	SPC	Bates, Caldwell, Carroll, Cass, Clay, Clinton and 9 more	3 hr
Feb 28, 10:30 PM CST	Tornado Watch	SPC	Barry, Barton, Benton, Camden, Cedar, Christian and 28 more	6 hr
Feb 28, 11:40 PM CST	Mesoscale Discussion	SPC	Barry, Camden, Cedar, Christian, Dade, Dallas and 13 more	95 min
Feb 29, 12:49 AM CST	Mesoscale Discussion	SPC	Bollinger, Butler, Cape Girardeau, Carter, Dunklin, Franklin and 19 more	56 min
Feb 29, 1:14 AM CST	Tornado Watch	SPC	Bollinger, Butler, Cape Girardeau, Carter, Crawford, Franklin and 19 more	11 hr
Feb 29, 3:20 AM CST	Tornado Watch	SPC	Dunklin, Pemiscot	9 hr
Feb 29, 3:53 AM CST	Mesoscale Discussion	SPC	Bollinger, Butler, Cape Girardeau, Carter, Dunklin, Madison and 9 more	97 min
Feb 29, 8:07 AM CST	Mesoscale Discussion	SPC	Dunklin, Mississippi, New Madrid, Pemiscot	53 min
Feb 28, 7:59 PM CST	Mesoscale Discussion	SPC	Adams, Buffalo, Butler, Clay, Colfax, Fillmore and 21 more	31 min

Nearby

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