Alert archive / Tennessee / Mesoscale Discussions in 2011

Mesoscale Discussion 1306

June 19, 2011Rabun County, Towns County, Georgia; 7 counties in North Carolina; 27 counties in Tennessee

The Storm Prediction Center issued this mesoscale discussion at Jun 19, 2011, 9:07 PM EDT for Rabun County, Towns County, Georgia; 7 counties in North Carolina; 27 counties in Tennessee. It was in force for 53 min.

The area

The outline as issued.

The facts

Issued
Jun 19, 2011, 9:07 PM EDT (01:07 UTC)
Expired
Jun 19, 2011, 10:00 PM EDT
In force
53 min
Issued by
the Storm Prediction Center
All 36 counties

Rabun County, GA, Towns County, GA, Cherokee County, NC, Clay County, NC, Graham County, NC, Haywood County, NC, Jackson County, NC, Macon County, NC, Swain County, NC, Anderson County, TN, Bledsoe County, TN, Blount County, TN, Bradley County, TN, Cannon County, TN, Cocke County, TN, Cumberland County, TN, DeKalb County, TN, Grainger County, TN, Hamblen County, TN, Hamilton County, TN, Jefferson County, TN, Knox County, TN, Loudon County, TN, McMinn County, TN, Meigs County, TN, Monroe County, TN, Morgan County, TN, Polk County, TN, Rhea County, TN, Roane County, TN, Sequatchie County, TN, Sevier County, TN, Union County, TN, Van Buren County, TN, Warren County, TN, White County, TN

The radar

The Knoxville radar (KMRX), 114 km from the middle of the area, began a volume at 01:11 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.

The nearest sounding before it

Nashville Metro, TN (KBNA), launched 00:00Z, 1.1 hours before the alert went out and 206 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-pSkew-T log-p diagram, Nashville Metro, TN at 00:00Z on 2011-06-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 3898 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Nashville Metro, TN at 00:00Z on 2011-06-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 63 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
3898 J/kg
Mixed-layer CIN
-6 J/kg
Mixed-layer LCL
955 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
63 m²/s²
0-3 km storm-relative helicity
127 m²/s²
Significant tornado parameter
3.2
Supercell composite
14.9

Open this sounding in Storm Lab

The text

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

801 
ACUS11 KWNS 200107
SWOMCD
SPC MCD 200107 
NCZ000-TNZ000-SCZ000-GAZ000-200200-

MESOSCALE DISCUSSION 1306
NWS STORM PREDICTION CENTER NORMAN OK
0807 PM CDT SUN JUN 19 2011

AREAS AFFECTED...MIDDLE/ERN TN...

CONCERNING...TORNADO WATCH 514...

VALID 200107Z - 200200Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 514 CONTINUES.

WW 511 WAS LOCALLY EXTENDED BY WFO MRX THROUGH 02Z. A NEW WW MAY BE
NEEDED TO REPLACE THIS EXTENSION BY 02Z AND MAY INCLUDE PORTIONS OF
WRN NC.

A PERSISTENT SUPERCELL WITH A HISTORY OF REPORTED GOLF BALL TO
BASEBALL-SIZED HAIL WAS CENTERED OVER CUMBERLAND/WHITE COUNTIES AS
OF 01Z. ADDITIONAL TSTM DEVELOPMENT HAS OCCURRED W/SWWD ALONG THE
FLANKING LINE/OUTFLOW...SUGGESTIVE OF SOME UPSCALE GROWTH INTO A
BROADER CLUSTER. 00Z BNA RAOB SAMPLED A VERY UNSTABLE AIR MASS WITH
MLCAPE AROUND 4000 J/KG. GIVEN EFFECTIVE SHEAR AROUND 40
KT...SUPERCELL STRUCTURES WILL LIKELY PERSIST WITH ATTENDANT LARGE
HAIL AND AN INCREASING DAMAGING WIND THREAT IF UPSCALE GROWTH
CONTINUES. ONSET OF NOCTURNAL COOLING/INCREASING MLCIN WOULD SUGGEST
THE OVERALL TORNADO THREAT WILL GRADUALLY SUBSIDE THIS EVENING.

..GRAMS.. 06/20/2011

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

ATTN...WFO...GSP...MRX...FFC...OHX...

LAT...LON   35788624 35968614 36188522 36408378 36158305 35788273
            34998296 34848331 34878392 34918431 35178523 35788624

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jun 19, 9:41 PM EDTSevere Thunderstorm WatchSPCElbert, Fannin, Franklin, Habersham, Hart, Lumpkin and 5 more5 hr
Jun 20, 9:53 AM EDTMesoscale DiscussionSPCMadison, Mitchell, Yancey97 min
Jun 20, 12:46 PM EDTMesoscale DiscussionSPCAlexander, Ashe, Avery, Burke, Caldwell, Mitchell and 2 more59 min
Jun 20, 2:36 PM EDTMesoscale DiscussionSPCAlamance, Caswell, Orange54 min

Nearby

Mesoscale Discussions in Tennessee, 2011Mesoscale Discussions in North Carolina, 2011Mesoscale Discussions in Georgia, 2011Every mesoscale discussion in 2011

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.