Alert archive / Tennessee / Mesoscale Discussions in 2021
Mesoscale Discussion 1053
The Storm Prediction Center issued this mesoscale discussion at Jun 21, 2021, 5:59 PM EDT for 21 counties in Tennessee; Scott County, City of Bristol, Virginia. It was in force for 91 min.
The area
The outline as issued.
The facts
- Issued
- Jun 21, 2021, 5:59 PM EDT (21:59 UTC)
- Expired
- Jun 21, 2021, 7:30 PM EDT
- In force
- 91 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
All 23 counties
Anderson County, TN, Blount County, TN, Bradley County, TN, Cocke County, TN, Grainger County, TN, Greene County, TN, Hamblen 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, Rhea County, TN, Roane County, TN, Sevier County, TN, Sullivan County, TN, Union County, TN, Washington County, TN, City of Bristol, VA, Scott County, VA
The radar
The Knoxville radar (KMRX), 19 km from the middle of the area, began a volume at 22:02 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
Nashville Metro, TN (KBNA), launched 12:00Z, 10.0 hours before the alert went out and 286 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
- 1530 J/kg
- Mixed-layer CIN
- -42 J/kg
- Mixed-layer LCL
- 919 m above ground
- 0-6 km bulk shear
- 40 kt
- 0-1 km storm-relative helicity
- 211 m²/s²
- 0-3 km storm-relative helicity
- 228 m²/s²
- Significant tornado parameter
- 1.3
- Supercell composite
- 9.6
The text
As transmitted.
383
ACUS11 KWNS 212200
SWOMCD
SPC MCD 212159
VAZ000-TNZ000-NCZ000-212330-
Mesoscale Discussion 1053
NWS Storm Prediction Center Norman OK
0459 PM CDT Mon Jun 21 2021
Areas affected...eastern Tennessee
Concerning...Severe potential...Watch unlikely
Valid 212159Z - 212330Z
Probability of Watch Issuance...20 percent
SUMMARY...Thunderstorms will continue to pose a risk for a few
strong to damaging gusts through about 00Z, followed by an overall
decrease in intensities. Due to the limited duration of remaining
threat, a WW will probably not be necessary.
DISCUSSION...Widely scattered to scattered thunderstorms continue
developing in the pre-frontal warm sector across eastern TN where
the atmosphere remains moderately unstable with up to 2000 J/kg
MLCAPE. Latest VAD wind profile from Morristown shows unidirectional
west southwest winds from 30-40 kt in the 2 - 6 km layer but with
weak vertical shear. This environment is supportive of multicells
capable of producing locally strong to damaging gusts. The primary
threat should persist another couple of hours, but storms should
begin a weakening trend after 00Z as the boundary layer stabilizes
with loss of diurnal heating.
..Dial/Grams.. 06/21/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GSP...MRX...
LAT...LON 36608169 35728332 35288409 35098511 35488513 36298398
36948235 36608169SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 21, 12:35 PM EDT | Mesoscale Discussion | SPC | Benton, Cannon, Carroll, Cheatham, Clay, Crockett and 38 more | 85 min |
| Jun 21, 1:52 PM EDT | Severe Thunderstorm Watch | SPC | Cannon, Cheatham, Clay, Davidson, DeKalb, Dickson and 17 more | 5 hr |
| Jun 21, 4:03 PM EDT | Mesoscale Discussion | SPC | Campbell, Cannon, Claiborne, Clay, Cumberland, Davidson and 16 more | 117 min |
| Jun 21, 12:31 PM EDT | Severe Thunderstorm Watch | SPC | Buchanan, Dickenson | 7 hr |
| Jun 21, 1:51 PM EDT | Mesoscale Discussion | SPC | Albemarle, Arlington, Augusta, Clarke, Culpeper, Fairfax and 27 more | 114 min |
| Jun 21, 2:20 PM EDT | Severe Thunderstorm Watch | SPC | Arlington, Augusta, Clarke, Culpeper, Fairfax, Fauquier and 23 more | 6 hr |
| Jun 21, 6:15 PM EDT | Mesoscale Discussion | SPC | Arlington, City of Falls Church | 60 min |
Nearby
Mesoscale Discussions in Tennessee, 2021Mesoscale Discussions in Virginia, 2021Every mesoscale discussion in 2021
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.