Alert archive / Tennessee / Mesoscale Discussions in 2021
Mesoscale Discussion 110
The Storm Prediction Center issued this mesoscale discussion at Feb 17, 2021, 1:00 PM CST for 4 states. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Feb 17, 2021, 1:00 PM CST (19:00 UTC)
- Expired
- Feb 17, 2021, 4:00 PM CST
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Heavy snow
All 75 counties
Colbert County, AL, Franklin County, AL, Lauderdale County, AL, Lawrence County, AL, Limestone County, AL, Madison County, AL, Allen County, KY, Clinton County, KY, Cumberland County, KY, Monroe County, KY, Simpson County, KY, Wayne County, KY, Alcorn County, MS, Benton County, MS, Itawamba County, MS, Lafayette County, MS, Lee County, MS, Marshall County, MS, Pontotoc County, MS, Prentiss County, MS, Tate County, MS, Tippah County, MS, Tishomingo County, MS, Union County, MS, Bedford County, TN, Benton County, TN, Cannon County, TN, Carroll County, TN, Cheatham County, TN, Chester County, TN, Clay County, TN, Coffee County, TN, Cumberland County, TN, Davidson County, TN, Decatur County, TN, DeKalb County, TN, Dickson County, TN, Fayette County, TN, Fentress County, TN, Franklin County, TN, Giles County, TN, Grundy County, TN, Hardeman County, TN, Hardin County, TN, Haywood County, TN, Henderson County, TN, Hickman County, TN, Houston County, TN, Humphreys County, TN, Jackson County, TN, Lawrence County, TN, Lewis County, TN, Lincoln County, TN, Macon County, TN, Madison County, TN, Marshall County, TN, Maury County, TN, McNairy County, TN, Montgomery County, TN, Moore County, TN, Overton County, TN, Perry County, TN, Pickett County, TN, Putnam County, TN, Robertson County, TN, Rutherford County, TN, Smith County, TN, Sumner County, TN, Trousdale County, TN, Van Buren County, TN, Warren County, TN, Wayne County, TN, White County, TN, Williamson County, TN, Wilson County, TN
The radar
The Nashville radar (KOHX), 132 km from the middle of the area, began a volume at 19:00 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, 7.0 hours before the alert went out and 121 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
- 854 m above ground
- 0-6 km bulk shear
- 65 kt
- 0-1 km storm-relative helicity
- 97 m²/s²
- 0-3 km storm-relative helicity
- 175 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
999
ACUS11 KWNS 171900
SWOMCD
SPC MCD 171900
KYZ000-TNZ000-ALZ000-MSZ000-172200-
Mesoscale Discussion 0110
NWS Storm Prediction Center Norman OK
0100 PM CST Wed Feb 17 2021
Areas affected...northern Mississippi through middle Tennessee and
far southern Kentucky
Concerning...Heavy snow
Valid 171900Z - 172200Z
SUMMARY...Moderate to locally heavy snow continues to spread
northeastward into the discussion area from the southwest. 1" per
hour rates will gradually become increasingly likely over the course
of the afternoon.
DISCUSSION...Heavier reflectivities are beginning to appear in radar
mosaic imagery from bear Oxford, MS to southwest of Nashville, TN
over the past hour. The precipitation itself is likely tied to
isentropic lift across upstream areas of Arkansas/Louisiana where
50-60 kt low-level flow continues to impinge on a shallow
sub-freezing airmass. The precipitation itself is outpacing most
model guidance, and with low-level moistening occurring beneath the
precipitation shield, areas of moderate to occasionally heavy snow
should begin across the discussion area over the next 1-2 hours or
so. Snow should be the be dominant precip type, though point
forecast soundings indicate enough of a warm layer aloft to support
occasional mixing with sleet at times.
..Cook.. 02/17/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MRX...JKL...LMK...OHX...BMX...HUN...MEG...
LAT...LON 35728931 36328805 36698681 36998548 36878467 36028475
35068578 34378752 34048888 34208979 34629011 35068978
35728931SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Feb 17, 9:15 AM CST | Mesoscale Discussion | SPC | Bolivar, Coahoma, DeSoto, Marshall, Panola, Quitman and 2 more | 6 hr |
| Feb 17, 10:53 AM CST | Mesoscale Discussion | SPC | Adams, Attala, Calhoun, Carroll, Chickasaw, Choctaw and 46 more | 6 hr |
| Feb 17, 3:22 PM CST | Mesoscale Discussion | SPC | Alcorn, Benton, Coahoma, DeSoto, Marshall, Panola and 4 more | 4 hr |
| Feb 17, 5:38 PM CST | Mesoscale Discussion | SPC | Harrison | 3 hr |
Nearby
Mesoscale Discussions in Tennessee, 2021Mesoscale Discussions in Mississippi, 2021Mesoscale Discussions in Alabama, 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.