Alert archive / Nebraska / Mesoscale Discussions in 2012

Mesoscale Discussion 2178

December 19, 20126 counties in Kansas; 21 counties in Nebraska

The Storm Prediction Center issued this mesoscale discussion at Dec 19, 2012, 6:19 PM CST for 6 counties in Kansas; 21 counties in Nebraska. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Dec 19, 2012, 6:19 PM CST (00:19 UTC)
Expired: Dec 19, 2012, 10:15 PM CST
In force: 4 hr
Issued by: the Storm Prediction Center

All 27 counties

Decatur County, KS, Norton County, KS, Phillips County, KS, Rawlins County, KS, Sheridan County, KS, Thomas County, KS, Adams County, NE, Buffalo County, NE, Clay County, NE, Fillmore County, NE, Franklin County, NE, Furnas County, NE, Gosper County, NE, Hall County, NE, Hamilton County, NE, Harlan County, NE, Kearney County, NE, Merrick County, NE, Nuckolls County, NE, Phelps County, NE, Polk County, NE, Red Willow County, NE, Saline County, NE, Seward County, NE, Thayer County, NE, Webster County, NE, York County, NE

The radar

The Grand Island radar (KUEX), 52 km from the middle of the area, began a volume at 00:20 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

N. Platte/Lee Bi, NE (KLBF), launched 00:00Z, 0.3 hours before the alert went out and 164 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: 527 m above ground
0-6 km bulk shear: 61 kt
0-1 km storm-relative helicity: -105 m²/s²
0-3 km storm-relative helicity: 238 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.

551 
ACUS11 KWNS 200019
SWOMCD
SPC MCD 200019 
NEZ000-KSZ000-200415-

MESOSCALE DISCUSSION 2178
NWS STORM PREDICTION CENTER NORMAN OK
0619 PM CST WED DEC 19 2012

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

CONCERNING...BLIZZARD 

VALID 200019Z - 200415Z

SUMMARY...A CESSATION OF THE HEAVIEST SNOWFALL RATES IS EXPECTED TO
OCCUR FIRST OVER NWRN KS AND ADJACENT PARTS OF SWRN NEB DURING THE
00-03 UTC PERIOD WITH SNOWFALL RATES ABATING SUBSTANTIALLY DURING
THE 03-06 UTC PERIOD FARTHER E OVER MAINLY S-CNTRL NEB AND FAR
N-CNTRL KS.  BLIZZARD CONDITIONS SHOULD CONTINUE INTO THE EVENING
HOURS ACROSS THE DISCUSSION AREA...OWING TO REDUCED VISIBILITIES AND
FREQUENT WIND GUSTS AOA 35 MPH.

DISCUSSION...SURFACE MESOANALYSIS PLACES A 996MB LOW ALONG THE OK/KS
BORDER 40 MI SSW ICT.  AS THE UPPER TROUGH AND ASSOCIATED DEEP LAYER
FORCING FOR ASCENT PIVOT EWD FROM NEAR THE CO/KS/OK BORDER TO
E-CNTRL KS BY 06 UTC...THE DEEPENING/DEVELOPMENT OF THE DEEP LAYER
CYCLONE WILL OCCUR FROM NEAR ITS CURRENT POSITION ALONG THE KS/OK
BORDER NEWD TO NWRN MO/NERN KS BY 06 UTC.  AS THIS OCCURS...EXPECT
THE HEAVIEST SNOWFALL RATES TO RESIDE FROM NWRN KS /0.50-LOCALLY 1
INCH PER HR FROM 00-02 UTC/ TO S-CNTRL NEB /1-1.5 INCH PER HR FROM
00-06 UTC/ AND CORRESPONDINGLY ABATING IN A GRADUAL MANNER IN A
GENERAL WSW-ENE DIRECTION.  IN THE MEANTIME...THE HEAVIEST SNOWFALL
RATES WILL LIKELY EXIST DURING THE NEXT FEW HOURS IN THE HSI-LNK
CORRIDOR WHERE A REDUCTION IN STATIC STABILITY IS GREATEST IN
ASSOCIATION WITH A MID-LEVEL DRY SLOT IMPINGING TO THE S IN NERN KS.
 IT IS WITHIN THIS CORRIDOR THAT ISOLD LIGHTNING STRIKES HAVE BEEN
DETECTED...SIGNALING WHERE CONVECTIVE ENHANCEMENT MAY LOCALLY
INCREASE SNOWFALL RATES.  BRISK NLY WIND GUSTS FREQUENTLY AOA 35MPH
AND LOW VISIBILITIES WILL OCCUR THROUGH THE EVENING /ESPECIALLY IN
THE HEAVIEST SNOW BURSTS/.

..SMITH.. 12/20/2012

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

ATTN...WFO...OAX...GID...LBF...GLD...

LAT...LON   39730134 40919927 41299782 41079706 40449686 40149746
            39759912 39140112 39730134

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 19, 7:07 PM CST	Mesoscale Discussion	SPC	Cherokee, Crawford, Labette, Montgomery	53 min
Dec 19, 7:36 PM CST	Tornado Watch	SPC	Cherokee	6 hr
Dec 19, 9:32 PM CST	Mesoscale Discussion	SPC	Cass, Douglas, Johnson, Lancaster, Otoe, Saline and 4 more	5 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.