Alert archive / Tennessee / Mesoscale Discussions in 2021
Mesoscale Discussion 132
The Storm Prediction Center issued this mesoscale discussion at Feb 27, 2021, 6:06 PM CST for 34 counties in Tennessee. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Feb 27, 2021, 6:06 PM CST (00:06 UTC)
- Expired
- Feb 27, 2021, 8:30 PM CST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
All 34 counties
Bedford County, TN, Benton County, TN, Cannon County, TN, Carroll County, TN, Cheatham County, TN, Chester County, TN, Coffee County, TN, Crockett County, TN, Davidson County, TN, Decatur County, TN, Dickson County, TN, Gibson County, TN, Giles County, TN, Hardeman County, TN, Hardin County, TN, Haywood County, TN, Henderson County, TN, Hickman County, TN, Houston County, TN, Humphreys County, TN, Lawrence County, TN, Lewis County, TN, Lincoln County, TN, Madison County, TN, Marshall County, TN, Maury County, TN, McNairy County, TN, Montgomery County, TN, Moore County, TN, Perry County, TN, Rutherford County, TN, Wayne County, TN, Williamson County, TN, Wilson County, TN
The radar
The Nashville radar (KOHX), 133 km from the middle of the area, began a volume at 00:10 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 00:00Z, 0.1 hours before the alert went out and 123 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
- 35 J/kg
- Mixed-layer CIN
- -117 J/kg
- Mixed-layer LCL
- 527 m above ground
- 0-6 km bulk shear
- 70 kt
- 0-1 km storm-relative helicity
- 189 m²/s²
- 0-3 km storm-relative helicity
- 214 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
766
ACUS11 KWNS 280007
SWOMCD
SPC MCD 280006
TNZ000-ALZ000-MSZ000-280230-
Mesoscale Discussion 0132
NWS Storm Prediction Center Norman OK
0606 PM CST Sat Feb 27 2021
Areas affected...Tennessee Valley
Concerning...Severe potential...Watch unlikely
Valid 280006Z - 280230Z
Probability of Watch Issuance...20 percent
SUMMARY...A threat for strong wind gusts and hail is expected across
parts of western and middle Tennessee over the next few hours. Due
to the marginal nature of the threat, weather watch issuance is not
expected.
DISCUSSION...The latest surface analysis shows a quasi-stationary
front located from far northern Mississippi extending
east-northeastward across southern Tennessee. A corridor of
maximized low-level moisture is analyzed to the south of the front
where surface dewpoints are in the lower to mid 60s F. According to
the RAP, MLCAPE has increased into the 250 to 750 J/kg range along
this tongue of low-level moisture. Thunderstorms have recently
developed into western Tennessee along the northern edge of the
instability corridor. The storms are being supported by a warm
advection regime. The storms should continue to spread
east-northeastward across middle Tennessee over the next few hours.
The weak instability combined with 60-65 kt of deep-layer shear,
evident on the Nashville WSR-88D VWP will support a marginal wind
damage and hail threat. However, the threat is not expected to be
sufficient to warrant weather watch issuance.
..Broyles/Grams.. 02/28/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...OHX...HUN...MEG...
LAT...LON 34958763 34998881 35138935 35368956 35798939 36128888
36528757 36478644 36188595 35478583 35008642 34958763SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 28, 7:49 AM CST | Mesoscale Discussion | SPC | Henry, Obion, Stewart, Weakley | 116 min |
| Feb 28, 1:01 PM CST | Mesoscale Discussion | SPC | Benton, Carroll, Chester, Crockett, Decatur, Dyer and 16 more | 119 min |
| Feb 28, 2:22 PM CST | Tornado Watch | SPC | Benton, Carroll, Cheatham, Chester, Crockett, Davidson and 33 more | 8 hr |
| Feb 28, 4:40 PM CST | Mesoscale Discussion | SPC | Benton, Carroll, Cheatham, Chester, Crockett, Davidson and 34 more | 95 min |
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.