Alert archive / Nebraska / Mesoscale Discussions in 2012

Mesoscale Discussion 164

February 28, 201213 counties in Kansas; 35 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Feb 28, 2012, 2:25 PM CST for 13 counties in Kansas; 35 counties in Nebraska. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Feb 28, 2012, 2:25 PM CST (20:25 UTC)
Expired: Feb 28, 2012, 5:00 PM CST
In force: 3 hr
Issued by: the Storm Prediction Center

All 48 counties

Cloud County, KS, Ellis County, KS, Graham County, KS, Jewell County, KS, Marshall County, KS, Mitchell County, KS, Norton County, KS, Osborne 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, Custer County, NE, Dawson County, NE, Fillmore County, NE, Franklin County, NE, Frontier County, NE, Furnas County, NE, Gage County, NE, Gosper County, NE, Greeley County, NE, Hall County, NE, Hamilton County, NE, Harlan County, NE, Howard County, NE, Jefferson County, NE, Kearney County, NE, Lancaster County, NE, Lincoln County, NE, Merrick County, NE, Nance County, NE, Nuckolls County, NE, Phelps County, NE, Platte County, NE, Polk County, NE, Red Willow 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), 8 km from the middle of the area, began a volume at 20:28 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 39Feb 28, 3:55 PM CST

The nearest sounding before it

N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 8.4 hours before the alert went out and 198 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: 720 m above ground
0-6 km bulk shear: 50 kt
0-1 km storm-relative helicity: 456 m²/s²
0-3 km storm-relative helicity: 433 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.

044 
ACUS11 KWNS 282026
SWOMCD
SPC MCD 282025
NEZ000-KSZ000-282300-

MESOSCALE DISCUSSION 0164
NWS STORM PREDICTION CENTER NORMAN OK
0225 PM CST TUE FEB 28 2012

AREAS AFFECTED...N CNTRL KS INTO S CNTRL NEB

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 282025Z - 282300Z

STORMS SHOULD INCREASE IN INTENSITY AND COVERAGE THIS AFTERNOON
INTO THE EVENING FROM NRN KS INTO SRN NEB. DAMAGING
WINDS...MARGINALLY SEVERE HAIL...AND PERHAPS A TORNADO OR TWO WILL
BE POSSIBLE. A WATCH IS LIKELY TO BE ISSUED THIS AFTERNOON.

SURFACE ANALYSIS SHOWS A DEEPENING LOW OVER NW KS...WITH STRONG
PRESSURE FALLS ACROSS THE WARM SECTOR...BOUNDED ON THE N BY A WARM
FRONT DRAPED W-E ACROSS SRN NEB....AND TO THE W BY A COLD FRONT
CONSOLIDATING ACROSS ERN CO INTO ERN NM/W TX.

AHEAD OF THE COLD FRONT...A DRYLINE WAS DEVELOPING DUE TO VERY
STRONG BOUNDARY LAYER MIXING...FROM WRN KS INTO THE OK/TX
PANHANDLES. TO THE E...BOUNDARY LAYER DEWPOINTS WERE RISING THROUGH
THE LOWER TO MIDDLE 50S F...RESULTING IN MARGINAL INSTABILITY AROUND
500-750 J/KG.

SATELLITE IMAGERY ALSO CLEARLY SHOWS THE UPPER VORT CENTER OVER NERN
CO...WHICH WILL EVENTUALLY OVERSPREAD WRN NEB/KS AND OVERTAKE THE
DRYLINE. AS THIS OCCURS WITH TIME...COOLING ALOFT WILL STEEPEN LAPSE
RATES ALOFT...AND AN UPTICK IN CONVECTIVE INTENSITY IS EXPECTED. THE
MAIN MITIGATING FACTOR TO SEVERITY IS THE LOW LEVEL MOISTURE...WHICH
MAY STRUGGLE TO RISE INTO THE LOWER 50S F NEAR THE WARM FRONT AND
INTO NRN KS LATER TODAY.

THAT SAID...AS THE COLD FRONT ACCELERATES EWD...FORCING WILL BE
FAVORABLE FOR LONG LIVED CONVECTION...CAPABLE OF AT LEAST DAMAGING
WINDS. LOW LEVEL SHEAR WILL REMAIN STRONG...AND MAY RESULT IN
SUPERCELLS...OR EMBEDDED MESOCYCLONES IF LINE SEGMENTS OCCUR. THE
MARGINAL MOISTURE ALONG WITH TIME OF DAY BECOMING LATE WILL LIKELY
MITIGATE THE TORNADO THREAT.

..JEWELL.. 02/28/2012

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

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

LAT...LON   39239791 38869947 39089990 39710026 40460084 41010087
            41399989 41659861 41689749 41259682 40719653 40209640
            39679651 39239791

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Feb 28, 3:53 PM CST	Tornado Watch	SPC	Clay, Cloud, Dickinson, Geary, Jewell, Mitchell and 8 more	5 hr
Feb 28, 5:15 PM CST	Mesoscale Discussion	SPC	Barton, Brown, Butler, Chase, Clay, Dickinson and 26 more	2 hr
Feb 28, 5:41 PM CST	Tornado Watch	SPC	Barton, Butler, Chase, Cowley, Ellsworth, Harper and 11 more	3 hr

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.