Alert archive / Tennessee / Mesoscale Discussions in 2011
Mesoscale Discussion 773
The Storm Prediction Center issued this mesoscale discussion at May 13, 2011, 11:22 AM CDT for 6 states. It was in force for 113 min.
The area
The outline as issued.
The facts
- Issued
- May 13, 2011, 11:22 AM CDT (16:22 UTC)
- Expired
- May 13, 2011, 1:15 PM CDT
- In force
- 113 min
- Issued by
- the Storm Prediction Center
All 44 counties
Cherokee County, AL, Etowah County, AL, Catoosa County, GA, Chattooga County, GA, Fannin County, GA, Floyd County, GA, Gilmer County, GA, Gordon County, GA, Murray County, GA, Polk County, GA, Walker County, GA, Whitfield County, GA, Bell County, KY, Clay County, KY, Harlan County, KY, Knox County, KY, Leslie County, KY, Whitley County, KY, Cherokee County, NC, Graham County, NC, Swain County, NC, Anderson County, TN, Blount County, TN, Bradley County, TN, Campbell County, TN, Claiborne County, TN, Cocke County, TN, Grainger County, TN, Greene County, TN, Hamblen County, TN, Hamilton County, TN, Hancock County, TN, Hawkins County, TN, Jefferson County, TN, Knox County, TN, Loudon County, TN, McMinn County, TN, Meigs County, TN, Monroe County, TN, Polk County, TN, Roane County, TN, Sevier County, TN, Union County, TN, Lee County, VA
The radar
The Knoxville radar (KMRX), 125 km from the middle of the area, began a volume at 16:23 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, 4.4 hours before the alert went out and 204 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
- 1225 J/kg
- Mixed-layer CIN
- -55 J/kg
- Mixed-layer LCL
- 983 m above ground
- 0-6 km bulk shear
- 32 kt
- 0-1 km storm-relative helicity
- 40 m²/s²
- 0-3 km storm-relative helicity
- 35 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.1
The text
As transmitted, in the capitals the NWS used until 2016.
066
ACUS11 KWNS 131623
SWOMCD
SPC MCD 131622
TNZ000-VAZ000-KYZ000-NCZ000-GAZ000-ALZ000-131815-
MESOSCALE DISCUSSION 0773
NWS STORM PREDICTION CENTER NORMAN OK
1122 AM CDT FRI MAY 13 2011
AREAS AFFECTED...NERN AL...NWRN GA...ERN TN...AND SERN KY
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 131622Z - 131815Z
STORMS MAY CONTINUE TO POSE A LEAST A MODEST THREAT FOR ISOLATED
STRONG TO DAMAGING WIND GUSTS AND HAIL INTO THE AFTERNOON.
EXTENSIVE OUTFLOW BOUNDARY FROM SERN KY SSWWD THROUGH ERN TN AND
NERN AL IS MOVING EAST 25-30 KT. DIABATIC WARMING OF THE MOIST
BOUNDARY LAYER HAS RESULTED MODEST INSTABILITY WITH MLCAPE FROM
1000-1500 J/KG...BUT MID-LEVEL LAPSE RATES REMAIN WEAK. BOTH
OBSERVED AND PFC DATA INDICATE LITTLE CAP REMAINING AS SURFACE
TEMPERATURES APPROACH 80 F...SUGGESTING STORMS MAY CONTINUE
DEVELOPING ALONG THE OUTFLOW BOUNDARY AS IT ADVANCES EWD NEXT FEW
HOURS. EFFECTIVE SHEAR FROM 30-35 KT WILL SUPPORT MAINLY MULTICELL
CONVECTION. THE MODEST SHEAR AND WEAK LAPSE RATES COULD ULTIMATELY
SERVE AS LIMITING FACTORS FOR A MORE ROBUST THREAT...BUT THE
STRONGER STORMS MAY BE CAPABLE OF PRODUCING ISOLATED STRONG WIND
GUSTS AND HAIL.
..DIAL.. 05/13/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...GSP...MRX...JKL...FFC...OHX...BMX...HUN...
LAT...LON 34718561 36218447 37208393 37258298 36418245 34918399
33998518 33868619 34718561SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 13, 5:03 PM CDT | Mesoscale Discussion | SPC | Colbert, Cullman, Fayette, Franklin, Lamar, Lauderdale and 8 more | 57 min |
| May 13, 5:54 PM CDT | Severe Thunderstorm Watch | SPC | Colbert, Fayette, Franklin, Greene, Lamar, Lauderdale and 5 more | 6 hr |
| May 13, 12:10 PM CDT | Severe Thunderstorm Watch | SPC | Bartow, Catoosa, Chattooga, Cherokee, Dade, Dawson and 18 more | 6 hr |
| May 13, 2:47 PM CDT | Mesoscale Discussion | SPC | Banks, Barrow, Bartow, Cherokee, Cobb, Dawson and 22 more | 58 min |
| May 13, 3:44 PM CDT | Severe Thunderstorm Watch | SPC | Elbert, Franklin, Hart, Stephens | 8 hr |
| May 13, 12:01 PM CDT | Mesoscale Discussion | SPC | Carlisle, Fulton, Graves, Hickman | 89 min |
| May 13, 12:31 PM CDT | Severe Thunderstorm Watch | SPC | Ballard, Calloway, Carlisle, Fulton, Graves, Hickman and 3 more | 6 hr |
| May 13, 2:44 PM CDT | Mesoscale Discussion | SPC | Ballard, Carlisle, Fulton, Graves, Hickman | 2 hr |
| May 13, 3:36 PM CDT | Mesoscale Discussion | SPC | Alamance, Alexander, Alleghany, Anson, Ashe, Avery and 28 more | 24 min |
| May 13, 6:21 PM CDT | Severe Thunderstorm Watch | SPC | Bladen, Cumberland, Duplin, Edgecombe, Franklin, Greene and 11 more | 6 hr |
Nearby
Mesoscale Discussions in Tennessee, 2011Mesoscale Discussions in Georgia, 2011Mesoscale Discussions in Kentucky, 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.