Alert archive / Tennessee / Mesoscale Discussions in 2011
Mesoscale Discussion 621
The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2011, 11:39 AM CDT for 4 states. It was in force for 66 min.
The area
The outline as issued.
The facts
- Issued
- Apr 27, 2011, 11:39 AM CDT (16:39 UTC)
- Expired
- Apr 27, 2011, 12:45 PM CDT
- In force
- 66 min
- Issued by
- the Storm Prediction Center
All 34 counties
Cullman County, AL, DeKalb County, AL, Jackson County, AL, Madison County, AL, Marshall County, AL, Morgan County, AL, Catoosa County, GA, Dade County, GA, Murray County, GA, Walker County, GA, Whitfield County, GA, Cherokee County, NC, Bledsoe County, TN, Blount County, TN, Bradley County, TN, Cannon County, TN, Coffee County, TN, DeKalb County, TN, Franklin County, TN, Grundy County, TN, Hamilton County, TN, Loudon County, TN, Marion County, TN, McMinn County, TN, Meigs County, TN, Monroe County, TN, Moore County, TN, Polk County, TN, Rhea County, TN, Roane County, TN, Sequatchie County, TN, Van Buren County, TN, Warren County, TN, White County, TN
The radar
The Northeast Alabama radar (KHTX), 29 km from the middle of the area, began a volume at 16:38 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 12:00Z, 4.7 hours before the alert went out and 169 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.
- 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
The text
As transmitted, in the capitals the NWS used until 2016.
302
ACUS11 KWNS 271639
SWOMCD
SPC MCD 271639
NCZ000-GAZ000-TNZ000-ALZ000-271745-
MESOSCALE DISCUSSION 0621
NWS STORM PREDICTION CENTER NORMAN OK
1139 AM CDT WED APR 27 2011
AREAS AFFECTED...SOUTHEAST TN/NORTHERN AL INTO FAR WESTERN
NC/EXTREME NORTHWEST GA
CONCERNING...TORNADO WATCH 229...230...231...
VALID 271639Z - 271745Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH
229...230...231...CONTINUES.
DAMAGING WINDS/ISOLATED TORNADOES WILL REMAIN A CONCERN ACROSS
NORTHEAST AL AND FAR SOUTH-CENTRAL TN INTO EASTERN TN AND EVENTUALLY
FAR WESTERN NC/PERHAPS FAR NORTHWEST GA.
A NORTHEAST-SOUTHWEST ORIENTED SEVERE QUASI-LINEAR MCS CONTINUES TO
GROW UPSCALE/ORGANIZE AND ACCELERATE...CENTERED ALONG THE MIDDLE
TN/NORTH-CENTRAL AL BORDER AS OF 1630Z. IN ADDITION TO RECENT
TORNADO REPORTS...MEASURED SEVERE WIND GUSTS HAVE BEEN NOTED AT
LOCATIONS SUCH AS MUSCLE SHOALS AL /52 KT/ AND COURTLAND AL /53 KT/.
WIDESPREAD DAMAGING WINDS WILL BE A MARKED CONCERN...WITH TORNADOES
POSSIBLE AS WELL VIA EVOLVING EMBEDDED MESO-VORTICES AMID A SRH-RICH
ENVIRONMENT. AFTER A MORE IMMEDIATE IMPACT ON THE HUNTSVILLE
AREA...THESE STORMS SEEM LIKELY TO REACH THE CHATTANOOGA VICINITY
BEFORE 18Z /2PM LOCAL TIME/. AN ADDITIONAL WATCH IS NOT CURRENTLY
ANTICIPATED FOR EXTREME NORTHWEST GA DUE TO SMALL AREAL EXTENT OF
THE GA THREAT.
..GUYER.. 04/27/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...GSP...MRX...FFC...OHX...BMX...HUN...
LAT...LON 34188734 34528696 36098589 35768384 34978387 34698510
34048606 34028677 34188734SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 26, 7:59 PM CDT | Mesoscale Discussion | SPC | Colbert, Franklin, Lamar, Lauderdale, Lawrence, Limestone and 1 more | 2 hr |
| Apr 26, 9:33 PM CDT | Tornado Watch | SPC | Colbert, Franklin, Lauderdale | 7 hr |
| Apr 26, 11:33 PM CDT | Mesoscale Discussion | SPC | Colbert, Franklin, Lamar, Lauderdale, Marion | 117 min |
| Apr 27, 1:56 AM CDT | Mesoscale Discussion | SPC | Bibb, Blount, Cullman, Fayette, Greene, Hale and 12 more | 64 min |
| Apr 27, 2:26 AM CDT | Tornado Watch | SPC | Bibb, Blount, Calhoun, Cherokee, Chilton, Clay and 29 more | 6 hr |
| Apr 27, 8:08 AM CDT | Tornado Watch | SPC | Colbert, Cullman, DeKalb, Fayette, Franklin, Jackson and 10 more | 6 hr |
| Apr 27, 10:45 AM CDT | Mesoscale Discussion | SPC | Greene, Lamar, Marion, Pickens, Sumter | 90 min |
| Apr 27, 1:05 PM CDT | Mesoscale Discussion | SPC | Bibb, Blount, Calhoun, Cherokee, Chilton, Choctaw and 27 more | 85 min |
| Apr 27, 1:42 PM CDT | Tornado Watch | SPC | Autauga, Bibb, Blount, Butler, Calhoun, Cherokee and 41 more | 8 hr |
| Apr 27, 2:56 PM CDT | Mesoscale Discussion | SPC | Bibb, Blount, Calhoun, Cherokee, Chilton, Choctaw and 33 more | 2 hr |
| Apr 27, 5:01 PM CDT | Mesoscale Discussion | SPC | Autauga, Bibb, Blount, Butler, Calhoun, Cherokee and 38 more | 89 min |
| Apr 27, 5:41 PM CDT | Mesoscale Discussion | SPC | Barbour, Bullock, Chambers, Crenshaw, Elmore, Lee and 6 more | 34 min |
| Apr 27, 5:52 PM CDT | Tornado Watch | SPC | Barbour, Bullock, Chambers, Elmore, Lee, Macon and 5 more | 9 hr |
| Apr 27, 6:39 PM CDT | Mesoscale Discussion | SPC | Autauga, Bibb, Blount, Calhoun, Cherokee, Chilton and 26 more | 66 min |
| Apr 27, 6:19 AM CDT | Mesoscale Discussion | SPC | Bartow, Carroll, Chattooga, Cherokee, Clayton, Cobb and 22 more | 56 min |
| Apr 27, 6:48 AM CDT | Tornado Watch | SPC | Bartow, Butts, Carroll, Catoosa, Chattooga, Cherokee and 36 more | 2 hr |
| Apr 27, 7:34 AM CDT | Tornado Watch | SPC | Cherokee, Clay | 4 hr |
| Apr 27, 10:27 AM CDT | Tornado Watch | SPC | Cherokee, Clay | 6 hr |
| Apr 27, 11:51 AM CDT | Mesoscale Discussion | SPC | Alamance, Anson, Bertie, Bladen, Cabarrus, Caswell and 47 more | 84 min |
| Apr 27, 12:23 PM CDT | Tornado Watch | SPC | Alamance, Anson, Caswell, Chatham, Cumberland, Davidson and 28 more | 5 hr |
| Apr 27, 1:03 PM CDT | Mesoscale Discussion | SPC | Cherokee, Clay, Graham | 57 min |
| Apr 27, 2:22 PM CDT | Mesoscale Discussion | SPC | Alleghany, Ashe, Avery, Buncombe, Caldwell, Haywood and 6 more | 83 min |
| Apr 27, 3:36 PM CDT | Tornado Watch | SPC | Cherokee, Clay | 8 hr |
| Apr 27, 5:00 PM CDT | Mesoscale Discussion | SPC | Alamance, Caswell, Durham, Franklin, Granville, Guilford and 5 more | 60 min |
| Apr 27, 5:15 PM CDT | Tornado Watch | SPC | Alamance, Alleghany, Ashe, Caswell, Davidson, Durham and 15 more | 6 hr |
| Apr 27, 6:55 PM CDT | Mesoscale Discussion | SPC | Alamance, Caswell, Granville, Orange, Person, Rockingham | 65 min |
| Apr 26, 9:13 PM CDT | Mesoscale Discussion | SPC | Benton, Carroll, Chester, Crockett, Dyer, Fayette and 16 more | 62 min |
| Apr 26, 9:58 PM CDT | Tornado Watch | SPC | Bedford, Benton, Cannon, Carroll, Cheatham, Chester and 40 more | 7 hr |
| Apr 27, 4:33 AM CDT | Mesoscale Discussion | SPC | Bedford, Cannon, Clay, Coffee, Cumberland, DeKalb and 15 more | 57 min |
| Apr 27, 5:07 AM CDT | Tornado Watch | SPC | Bedford, Bledsoe, Cannon, Clay, Coffee, Cumberland and 27 more | 5 hr |
| Apr 27, 6:25 AM CDT | Mesoscale Discussion | SPC | Fayette, Hardeman, Shelby, Tipton | 65 min |
| Apr 27, 11:02 AM CDT | Tornado Watch | SPC | Hardin, McNairy | 8 hr |
| Apr 27, 12:08 PM CDT | Mesoscale Discussion | SPC | Benton, Carroll, Cheatham, Chester, Crockett, Decatur and 21 more | 67 min |
| Apr 27, 12:42 PM CDT | Severe Thunderstorm Watch | SPC | Benton, Carroll, Cheatham, Chester, Crockett, Davidson and 27 more | 5 hr |
| Apr 27, 3:06 PM CDT | Mesoscale Discussion | SPC | Benton, Carroll, Cheatham, Chester, Crockett, Davidson and 22 more | 54 min |
| Apr 27, 3:29 PM CDT | Tornado Watch | SPC | Carroll, Chester, Crockett, Decatur, Dyer, Fayette and 13 more | 5 hr |
| Apr 27, 5:38 PM CDT | Mesoscale Discussion | SPC | Anderson, Bedford, Bledsoe, Blount, Bradley, Cannon and 36 more | 97 min |
Nearby
Mesoscale Discussions in Tennessee, 2011Mesoscale Discussions in Alabama, 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.