Alert archive / Arkansas / Mesoscale Discussions in 2012

Mesoscale Discussion 2138

December 9, 201212 counties in Arkansas; DeSoto County, Mississippi; Shelby County, Tipton County, Tennessee

The Storm Prediction Center issued this mesoscale discussion at Dec 9, 2012, 1:46 AM CST for 12 counties in Arkansas; DeSoto County, Mississippi; Shelby County, Tipton County, Tennessee. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Dec 9, 2012, 1:46 AM CST (07:46 UTC)
Expired: Dec 9, 2012, 4:15 AM CST
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Crittenden County, AR, Cross County, AR, Garland County, AR, Lee County, AR, Lonoke County, AR, Monroe County, AR, Montgomery County, AR, Prairie County, AR, Pulaski County, AR, Saline County, AR, St. Francis County, AR, Woodruff County, AR, DeSoto County, MS, Shelby County, TN, Tipton County, TN

The radar

The Little Rock radar (KLZK), 23 km from the middle of the area, began a volume at 07:49 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

Little Rock, AR (KLZK), launched 00:00Z, 7.8 hours before the alert went out and 189 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: 271 J/kg
Mixed-layer CIN: -7 J/kg
Mixed-layer LCL: 551 m above ground
0-6 km bulk shear: 47 kt
0-1 km storm-relative helicity: 146 m²/s²
0-3 km storm-relative helicity: 179 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 2.2

Open this sounding in Storm Lab

The text

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

967 
ACUS11 KWNS 090747
SWOMCD
SPC MCD 090746
TNZ000-MSZ000-ARZ000-091015-

MESOSCALE DISCUSSION 2138
NWS STORM PREDICTION CENTER NORMAN OK
0146 AM CST SUN DEC 09 2012

AREAS AFFECTED...CNTRL AND ERN AR...WRN TN

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 090746Z - 091015Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...LOW-END SEVERE HAIL MAY PERSIST FOR A FEW MORE HOURS
ACROSS CNTRL AR...AND MAY SPREAD INTO WRN TN LATER THIS MORNING.

DISCUSSION...A BATCH OF THUNDERSTORMS ASSOCIATED WITH WARM ADVECTION
PERSISTS ACROSS CNTRL AR...WITH INDICATIONS OF SMALL SEVERE HAIL
CORES. STRONG WIND PROFILES ARE ALSO SUPPORTING SUPERCELL STRUCTURE
AT TIMES. A MARGINAL HAIL THREAT WILL PERSIST...AND COULD SHIFT EWD
WITH TIME BUT INTENSITIES SHOULD BE GENERALLY WEAKER FARTHER E AS
STORMS GET FARTHER AWAY FROM THE MOST UNSTABLE AIR.

ALTHOUGH SOME ROTATION HAS BEEN NOTED...THESE STORMS ARE ELEVATED
AND THE TORNADO THREAT WILL REMAIN LOW. HOWEVER...COLD DOWNDRAFTS
AND FAST MOTIONS COULD RESULT IN LOCALLY GUSTY WINDS.

..JEWELL/THOMPSON.. 12/09/2012

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

ATTN...WFO...MEG...LZK...

LAT...LON   34629382 35628968 35438945 35108944 34898963 34369315
            34359358 34369373 34489394 34629382

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 8, 10:18 PM CST	Mesoscale Discussion	SPC	Conway, Garland, Logan, Montgomery, Perry, Polk and 2 more	117 min
Dec 9, 12:38 PM CST	Mesoscale Discussion	SPC	Arkansas, Clark, Clay, Cleburne, Cleveland, Conway and 41 more	2 hr
Dec 9, 2:10 PM CST	Tornado Watch	SPC	Arkansas, Clay, Cleburne, Conway, Craighead, Crittenden and 29 more	9 hr
Dec 9, 5:04 PM CST	Mesoscale Discussion	SPC	Clark, Columbia, Dallas, Hempstead, Lafayette, Miller and 2 more	116 min
Dec 9, 5:47 PM CST	Severe Thunderstorm Watch	SPC	Ashley, Bradley, Calhoun, Chicot, Clark, Cleveland and 9 more	6 hr
Dec 9, 5:54 PM CST	Mesoscale Discussion	SPC	Arkansas, Clay, Cleburne, Craighead, Crittenden, Cross and 20 more	96 min

Nearby

Mesoscale Discussions in Arkansas, 2012 Mesoscale Discussions in Tennessee, 2012 Mesoscale Discussions in Mississippi, 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.