Alert archive / Tennessee / Mesoscale Discussions in 2011

Mesoscale Discussion 623

April 27, 201127 counties in Tennessee

The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2011, 12:08 PM CDT for 27 counties in Tennessee. It was in force for 67 min.

The area

The outline as issued.

The facts

Issued
Apr 27, 2011, 12:08 PM CDT (17:08 UTC)
Expired
Apr 27, 2011, 1:15 PM CDT
In force
67 min
Issued by
the Storm Prediction Center
All 27 counties

Benton County, TN, Carroll County, TN, Cheatham County, TN, Chester County, TN, Crockett County, TN, Decatur County, TN, Dickson County, TN, Fayette County, TN, Gibson County, TN, Hardeman County, TN, Hardin County, TN, Haywood County, TN, Henderson County, TN, Henry County, TN, Hickman County, TN, Houston County, TN, Humphreys County, TN, Lauderdale County, TN, Lewis County, TN, Madison County, TN, McNairy County, TN, Montgomery County, TN, Perry County, TN, Shelby County, TN, Stewart County, TN, Tipton County, TN, Weakley County, TN

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 12:00Z, 5.1 hours before the alert went out and 160 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 12:00Z on 2011-04-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 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 12:00Z on 2011-04-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -84 square meters per square second.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
714 m above ground
0-6 km bulk shear
57 kt
0-1 km storm-relative helicity
-84 m²/s²
0-3 km storm-relative helicity
-38 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.

897 
ACUS11 KWNS 271708
SWOMCD
SPC MCD 271708 
TNZ000-KYZ000-ARZ000-271815-

MESOSCALE DISCUSSION 0623
NWS STORM PREDICTION CENTER NORMAN OK
1208 PM CDT WED APR 27 2011

AREAS AFFECTED...WRN TN / LOWER TN RIVER VALLEY

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 271708Z - 271815Z

AIRMASS IS TRYING TO RECOVER OVER WRN TN IN WAKE OF MCS THIS
MORNING.  VERY STRONG WIND PROFILE IN PLACE MAY WARRANT TORNADO
WATCH CONSIDERATION...ESPECIALLY IF SURFACE-BASED DESTABILIZATION
CAN OCCUR IN THE NEAR TERM.

RECENT SURFACE ANALYSIS PLACES A 994 LOW IN N-CNTRL AR WITH AN
OUTFLOW BOUNDARY...ATTENDANT TO THE MCS NOW ONGOING OVER SRN MIDDLE
TN/NRN AL...SLOWLY LIFTING NWD AND BECOMING DIFFUSE ACROSS FAR NRN
MS.  AN AREA OF ENHANCED SURFACE PRESSURE FALLS FROM MEM N AND NEWD
TOWARDS MKL AND PAH ARE IN RESPONSE TO STRONG DEEP UPWARD VERTICAL
MOTION RESPONSE MOVING TOWARDS THE REGION FROM THE W.  COMPLICATING
FACTOR HINGES ON SCATTERED-WIDESPREAD STORMS BEGINNING TO DEVELOP
OVER THE AREA IN WAKE OF THE MCS DUE IN PART TO LIFT PROVIDED BY THE
BOUNDARY/DIFFERENTIAL HEATING ZONE.  THESE STORMS WILL LIKELY
INHIBIT OR AT LEAST DELAY SURFACE-BASED DESTABILIZATION ACROSS THIS
AREA.  DESPITE THESE CAVEATS...A VERY STRONG VERTICAL WIND PROFILE
SAMPLED BY KNQA VAD /AOA 35 KTS 0-1 KM SHEAR/ WILL SUPPORT UPDRAFT
ORGANIZATION/ROTATION.  PRIOR TO A TORNADO THREAT DEVELOPING...IN
THE NEAR-TERM IT APPEARS THAT THERE IS AN INCREASING THREAT FOR
ISOLD LARGE HAIL/DMGG WINDS WITH THE MORE VIGOROUS CORES.

..SMITH.. 04/27/2011

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

ATTN...WFO...LMK...OHX...PAH...MEG...

LAT...LON   35109030 35948960 36538824 36858729 36738697 36138694
            35588730 35038824 35109030

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 26, 7:59 PM CDTMesoscale DiscussionSPCBedford, Cheatham, Davidson, Dickson, Giles, Hardin and 11 more2 hr
Apr 26, 9:13 PM CDTMesoscale DiscussionSPCBenton, Carroll, Chester, Crockett, Dyer, Fayette and 16 more62 min
Apr 26, 9:58 PM CDTTornado WatchSPCBedford, Benton, Cannon, Carroll, Cheatham, Chester and 40 more7 hr
Apr 27, 2:26 AM CDTTornado WatchSPCFranklin, Lincoln, Moore6 hr
Apr 27, 4:33 AM CDTMesoscale DiscussionSPCBedford, Cannon, Clay, Coffee, Cumberland, DeKalb and 15 more57 min
Apr 27, 5:07 AM CDTTornado WatchSPCBedford, Bledsoe, Cannon, Clay, Coffee, Cumberland and 27 more5 hr
Apr 27, 6:25 AM CDTMesoscale DiscussionSPCFayette, Hardeman, Shelby, Tipton65 min
Apr 27, 7:34 AM CDTTornado WatchSPCAnderson, Blount, Bradley, Campbell, Claiborne, Grainger and 13 more4 hr
Apr 27, 8:08 AM CDTTornado WatchSPCFranklin, Lincoln, Moore6 hr
Apr 27, 10:27 AM CDTTornado WatchSPCAnderson, Bedford, Bledsoe, Blount, Bradley, Cannon and 29 more6 hr
Apr 27, 11:02 AM CDTTornado Watch PDSSPCHardin, McNairy8 hr
Apr 27, 11:39 AM CDTMesoscale DiscussionSPCBledsoe, Blount, Bradley, Cannon, Coffee, DeKalb and 16 more66 min
Apr 27, 12:42 PM CDTSevere Thunderstorm WatchSPCBenton, Carroll, Cheatham, Chester, Crockett, Davidson and 27 more5 hr
Apr 27, 1:03 PM CDTMesoscale DiscussionSPCBledsoe, Blount, Bradley, Grundy, Hamilton, Loudon and 10 more57 min
Apr 27, 1:05 PM CDTMesoscale DiscussionSPCFranklin, Giles, Lawrence, Lincoln, Marshall, Maury and 1 more85 min
Apr 27, 1:42 PM CDTTornado Watch PDSSPCFranklin, Lincoln, Moore8 hr
Apr 27, 2:22 PM CDTMesoscale DiscussionSPCAnderson, Blount, Campbell, Carter, Claiborne, Cocke and 17 more83 min
Apr 27, 2:56 PM CDTMesoscale DiscussionSPCFranklin, Lincoln, Marion2 hr
Apr 27, 3:06 PM CDTMesoscale DiscussionSPCBenton, Carroll, Cheatham, Chester, Crockett, Davidson and 22 more54 min
Apr 27, 3:29 PM CDTTornado WatchSPCCarroll, Chester, Crockett, Decatur, Dyer, Fayette and 13 more5 hr
Apr 27, 3:36 PM CDTTornado Watch PDSSPCAnderson, Bedford, Benton, Bledsoe, Blount, Bradley and 66 more8 hr
Apr 27, 5:38 PM CDTMesoscale DiscussionSPCAnderson, Bedford, Bledsoe, Blount, Bradley, Cannon and 36 more97 min

Nearby

Mesoscale Discussions in Tennessee, 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.