Alert archive / Kentucky / Mesoscale Discussions in 2021
Mesoscale Discussion 1985
The Storm Prediction Center issued this mesoscale discussion at Dec 10, 2021, 6:52 PM EST for 5 counties in Indiana; 23 counties in Kentucky; 15 counties in Tennessee. It was in force for 83 min.
The area
The outline as issued.
The facts
- Issued
- Dec 10, 2021, 6:52 PM EST (23:52 UTC)
- Expired
- Dec 10, 2021, 8:15 PM EST
- In force
- 83 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...tornado watch likely
- Chance of a watch
- 95%
All 43 counties
Crawford County, IN, Floyd County, IN, Harrison County, IN, Perry County, IN, Spencer County, IN, Allen County, KY, Breckinridge County, KY, Bullitt County, KY, Butler County, KY, Christian County, KY, Daviess County, KY, Edmonson County, KY, Grayson County, KY, Hancock County, KY, Hardin County, KY, Hart County, KY, Hopkins County, KY, Jefferson County, KY, Larue County, KY, Logan County, KY, McLean County, KY, Meade County, KY, Muhlenberg County, KY, Ohio County, KY, Simpson County, KY, Todd County, KY, Trigg County, KY, Warren County, KY, Benton County, TN, Cheatham County, TN, Davidson County, TN, Dickson County, TN, Hickman County, TN, Houston County, TN, Humphreys County, TN, Lewis County, TN, Maury County, TN, Montgomery County, TN, Perry County, TN, Robertson County, TN, Stewart County, TN, Sumner County, TN, Williamson County, TN
The radar
The Ft Campbell radar (KHPX), 65 km from the middle of the area, began a volume at 23:54 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, 11.9 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
- 12 J/kg
- Mixed-layer CIN
- -126 J/kg
- Mixed-layer LCL
- 525 m above ground
- 0-6 km bulk shear
- 60 kt
- 0-1 km storm-relative helicity
- 260 m²/s²
- 0-3 km storm-relative helicity
- 372 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
356
ACUS11 KWNS 102353
SWOMCD
SPC MCD 102352
KYZ000-INZ000-TNZ000-110115-
Mesoscale Discussion 1985
NWS Storm Prediction Center Norman OK
0552 PM CST Fri Dec 10 2021
Areas affected...Portions of western Kentucky and Middle Tennessee.
Concerning...Severe potential...Tornado Watch likely
Valid 102352Z - 110115Z
Probability of Watch Issuance...95 percent
SUMMARY...A new tornado watch is needed downstream of tornado watch
552.
DISCUSSION...Warm air advection showers have started producing
lightning across portions of southern Illinois and western Kentucky.
Expect a slow increase in storm coverage and intensity across this
region. This activity (including a tornado warned storm entering
Calloway County, Kentucky) will move east of tornado watch 552 in
the next 30 to 60 minutes. The HPX VWP shows a very favorable
low-level shear environment with 0-1 km SRH around 400 m2/s2
indicating the potential for strong tornadoes. Therefore a
downstream tornado watch will be needed. The eastward extent of the
threat will be limited due to decreasing instability, but at least
some threat is expected to near I-65. This area will likely need to
be in a watch for an extended period due to multiple rounds of
convection continuing for most of the night.
..Bentley/Grams.. 12/10/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LMK...OHX...PAH...MEG...
LAT...LON 38208699 38428644 38408549 37798549 35988660 35158758
35848828 36978790 38208699SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 10, 4:07 PM EST | Tornado Watch | SPC | Gibson, Pike, Posey, Spencer, Vanderburgh, Warrick | 11 hr |
| Dec 10, 2:35 PM EST | Mesoscale Discussion | SPC | Fulton | 2 hr |
| Dec 10, 5:45 PM EST | Mesoscale Discussion | SPC | Ballard, Carlisle, Fulton, Graves, Hickman, Livingston and 1 more | 90 min |
| Dec 10, 6:17 PM EST | Mesoscale Discussion | SPC | Chester, Fayette, Hardeman, Hardin, Henderson, McNairy and 1 more | 88 min |
Nearby
Mesoscale Discussions in Kentucky, 2021Mesoscale Discussions in Tennessee, 2021Mesoscale Discussions in Indiana, 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.