Alert archive / Tennessee / Mesoscale Discussions in 2021
Mesoscale Discussion 282
The Storm Prediction Center issued this mesoscale discussion at Mar 27, 2021, 3:42 PM CDT for 18 counties in Tennessee. It was in force for 93 min.
The area
The outline as issued.
The facts
- Issued
- Mar 27, 2021, 3:42 PM CDT (20:42 UTC)
- Expired
- Mar 27, 2021, 5:15 PM CDT
- In force
- 93 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 59
Counties Chester County, TN, Crockett County, TN, Decatur County, TN, Fayette County, TN, Hardeman County, TN, Hardin County, TN, Haywood County, TN, Henderson County, TN, Hickman County, TN, Lauderdale County, TN, Lawrence County, TN, Lewis County, TN, Madison County, TN, McNairy County, TN, Perry County, TN, Shelby County, TN, Tipton County, TN, Wayne County, TN
The radar
The Memphis radar (KNQA), 107 km from the middle of the area, began a volume at 20:45 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
Little Rock, AR (KLZK), launched 12:00Z, 8.7 hours before the alert went out and 131 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
- 265 J/kg
- Mixed-layer CIN
- -202 J/kg
- Mixed-layer LCL
- 853 m above ground
- 0-6 km bulk shear
- 52 kt
- 0-1 km storm-relative helicity
- 180 m²/s²
- 0-3 km storm-relative helicity
- 151 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.4
The text
As transmitted.
165
ACUS11 KWNS 272042
SWOMCD
SPC MCD 272042
TNZ000-ARZ000-272215-
Mesoscale Discussion 0282
NWS Storm Prediction Center Norman OK
0342 PM CDT Sat Mar 27 2021
Areas affected...Portions of extreme eastern AR into western/middle
TN
Concerning...Tornado Watch 59...
Valid 272042Z - 272215Z
The severe weather threat for Tornado Watch 59 continues.
SUMMARY...The threat for tornadoes and large hail should increase
across parts of western/middle TN through the remainder of the
afternoon.
DISCUSSION...Based on recent radar and visible satellite imagery, it
appears that robust updraft development is imminent across parts of
southwestern TN. VWP from KNQA shows around 25-30 kt of 0-1 km
shear, and nearly 200 m2/s2 of 0-1 km SRH. With 50-60+ kt of
effective bulk shear and 1500-2000 J/kg of MLCAPE present along and
south of a warm front, supercells still appear likely. The best
tornado threat across Tornado Watch 59 will probably focus across
southwestern TN and vicinity over the next couple of hours in the
vicinity of the warm front, as the greatest low-level shear is
present there. Large hail, potentially greater than 2 inches in
diameter, also remains a concern given the moderate to strong
instability and steep mid-level lapse rates.
..Gleason.. 03/27/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OHX...MEG...
LAT...LON 35028875 35029022 35469029 35788971 35918879 35928726
35498707 35058739 35028875SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 27, 2:05 AM CDT | Mesoscale Discussion | SPC | Bedford, Cannon, Chester, Coffee, Decatur, Fayette and 18 more | 115 min |
| Mar 27, 7:41 AM CDT | Mesoscale Discussion | SPC | Anderson, Bedford, Bledsoe, Campbell, Cannon, Claiborne and 28 more | 2 hr |
| Mar 27, 10:00 AM CDT | Mesoscale Discussion | SPC | Anderson, Blount, Campbell, Claiborne, Cocke, Grainger and 12 more | 90 min |
| Mar 27, 11:55 AM CDT | Mesoscale Discussion | SPC | Bedford, Bledsoe, Bradley, Cannon, Carroll, Chester and 39 more | 3 hr |
| Mar 27, 1:51 PM CDT | Tornado Watch | SPC | Bedford, Benton, Carroll, Chester, Coffee, Crockett and 24 more | 7 hr |
| Mar 27, 6:42 PM CDT | Mesoscale Discussion | SPC | Crockett, Fayette, Haywood, Lauderdale, Shelby, Tipton | 2 hr |
Nearby
Mesoscale Discussions in Tennessee, 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.