Alert archive / Nebraska / Mesoscale Discussions in 2012

Mesoscale Discussion 169

February 28, 201211 counties in Kansas; 27 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Feb 28, 2012, 7:59 PM CST for 11 counties in Kansas; 27 counties in Nebraska. It was in force for 31 min.

The area

The outline as issued.

The facts

Issued: Feb 28, 2012, 7:59 PM CST (01:59 UTC)
Expired: Feb 28, 2012, 8:30 PM CST
In force: 31 min
Issued by: the Storm Prediction Center

All 38 counties

Clay County, KS, Cloud County, KS, Jewell County, KS, Mitchell County, KS, Osborne County, KS, Ottawa County, KS, Phillips County, KS, Republic County, KS, Rooks County, KS, Smith County, KS, Washington County, KS, Adams County, NE, Buffalo County, NE, Butler County, NE, Clay County, NE, Colfax County, NE, Fillmore County, NE, Franklin County, NE, Greeley County, NE, Hall County, NE, Hamilton County, NE, Harlan County, NE, Howard County, NE, Jefferson County, NE, Kearney County, NE, Merrick County, NE, Nance County, NE, Nuckolls County, NE, Phelps County, NE, Platte County, NE, Polk County, NE, Saline County, NE, Seward County, NE, Sherman County, NE, Thayer County, NE, Valley County, NE, Webster County, NE, York County, NE

The radar

The Grand Island radar (KUEX), 38 km from the middle of the area, began a volume at 01:59 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.

Tornado Watch 41Feb 28, 8:10 PM CST

The nearest sounding before it

N. Platte/Lee Bi, NE (KLBF), launched 00:00Z, 2.0 hours before the alert went out and 182 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: 780 m above ground
0-6 km bulk shear: 50 kt
0-1 km storm-relative helicity: -186 m²/s²
0-3 km storm-relative helicity: 22 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.

113 
ACUS11 KWNS 290200
SWOMCD
SPC MCD 290159 COR
NEZ000-KSZ000-290230-

MESOSCALE DISCUSSION 0169
NWS STORM PREDICTION CENTER NORMAN OK
0759 PM CST TUE FEB 28 2012

AREAS AFFECTED...S-CNTRL NEB AND N-CNTRL KS

CONCERNING...TORNADO WATCH 39...

VALID 290159Z - 290230Z

CORRECTED FOR GRAPHIC

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 39 CONTINUES.

MODEST SFC BASED INSTABILITY COMBINED WITH FAVORABLE VERTICAL SHEAR
PROFILES JUST AHEAD OF A DRYLINE/COLD FRONT WILL ALLOW THE SEVERE
THREAT TO CONTINUE ACROSS CENTRAL AND EASTERN PORTIONS OF WW 39 THE
NEXT COUPLE OF HOURS. LATEST SFC ANALYSIS INDICATED A COLD FRONT
EXTENDING FROM NEAR BBW TO MCK SWWD TO JUST E OF GLD. THE DRYLINE
WAS STILL SOMEWHAT AHEAD OF THE COLD FRONT EXTENDING SWD FROM BBW TO
NEAR HDE TOWARD HYS. IT WAS ALONG THE DRYLINE IN A NARROW WARM
SECTOR THAT THUNDERSTORMS WERE CONTINUING TO DEVELOP AND MAINTAIN
SEVERE CHARACTERISTICS FROM TIME TO TIME. WHILE THE THREAT MAY BE
TRANSITIONING TO MORE OF A DAMAGING WIND/HAIL THREAT AS STORMS TAKE
ON MORE OF A LINEAR MODE...GIVEN THE INTENSE LOW LEVEL SHEAR A
TORNADO OR TWO STILL CAN NOT BE RULED OUT THROUGH 03Z.

WHILE STORMS NEAR THE EASTERN EDGE OF THE WW HAVE PREVIOUSLY SHOWED
SEVERE CHARACTERISTICS...THEY HAVE SINCE WEAKENED AND A WATCH
DOWNSTREAM IS NOT CURRENTLY ANTICIPATED BUT TRENDS WILL BE
MONITORED.

..LEITMAN.. 02/29/2012

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

ATTN...WFO...OAX...TOP...ICT...GID...LBF...DDC...GLD...

LAT...LON   41709970 41689683 39089679 39129959 41709970

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 28, 7:57 PM CST	Mesoscale Discussion	SPC	Butler, Chase, Chautauqua, Cowley, Elk, Greenwood and 9 more	48 min
Feb 28, 8:10 PM CST	Tornado Watch	SPC	Allen, Anderson, Brown, Butler, Chase, Chautauqua and 25 more	5 hr
Feb 28, 9:47 PM CST	Mesoscale Discussion	SPC	Allen, Anderson, Bourbon, Cherokee, Crawford, Franklin and 9 more	58 min
Feb 28, 10:07 PM CST	Severe Thunderstorm Watch	SPC	Johnson, Linn, Miami, Wyandotte	3 hr
Feb 28, 10:30 PM CST	Tornado Watch	SPC	Bourbon, Cherokee, Crawford	6 hr
Feb 28, 8:23 PM CST	Mesoscale Discussion	SPC	Burt, Butler, Cass, Colfax, Cuming, Dodge and 15 more	37 min

Nearby

Mesoscale Discussions in Nebraska, 2012 Mesoscale Discussions in Kansas, 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.