Alert archive / Kentucky / Mesoscale Discussions in 2021
Mesoscale Discussion 1964
The Storm Prediction Center issued this mesoscale discussion at Dec 6, 2021, 2:47 AM CST for 16 counties in Kentucky; Mississippi County, Missouri. It was in force for 88 min.
The area
The outline as issued.
The facts
- Issued
- Dec 6, 2021, 2:47 AM CST (08:47 UTC)
- Expired
- Dec 6, 2021, 4:15 AM CST
- In force
- 88 min
- Issued by
- the Storm Prediction Center
- Concerning
- Tornado watch 551
Counties Ballard County, KY, Caldwell County, KY, Calloway County, KY, Carlisle County, KY, Christian County, KY, Fulton County, KY, Graves County, KY, Hickman County, KY, Hopkins County, KY, Livingston County, KY, Lyon County, KY, Marshall County, KY, McCracken County, KY, Muhlenberg County, KY, Todd County, KY, Trigg County, KY, Mississippi County, MO
The radar
The Paducah radar (KPAH), 36 km from the middle of the area, began a volume at 08:50 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, 8.8 hours before the alert went out and 185 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
- 666 J/kg
- Mixed-layer CIN
- -18 J/kg
- Mixed-layer LCL
- 658 m above ground
- 0-6 km bulk shear
- 38 kt
- 0-1 km storm-relative helicity
- 346 m²/s²
- 0-3 km storm-relative helicity
- 484 m²/s²
- Significant tornado parameter
- 1.1
- Supercell composite
- 5.4
The text
As transmitted.
843
ACUS11 KWNS 060847
SWOMCD
SPC MCD 060847
KYZ000-TNZ000-ILZ000-MOZ000-061015-
Mesoscale Discussion 1964
NWS Storm Prediction Center Norman OK
0247 AM CST Mon Dec 06 2021
Areas affected...southwestern Kentucky
Concerning...Tornado Watch 551...
Valid 060847Z - 061015Z
The severe weather threat for Tornado Watch 551 continues.
SUMMARY...Local risk for severe weather -- mainly in the form of
gusty/damaging winds -- will continue over the next couple of hours.
As WW 551 nears its scheduled 10Z expiration, new/downstream WW
issuance is not anticipated.
DISCUSSION...Latest radar loop shows a frontal band of convection
moving across northern and western Kentucky at this time. The
strongest storms within the broader bend exist within in a short
segment about to cross the Mississippi River from far southeastern
Missouri and into far western Kentucky.
Ahead of the frontal band, a secondary, loosely organized zone of
pre-frontal convection is indicated. Ahead of the front across
Kentucky, a seasonally moist boundary layer (dewpoints in the mid
50s to near 60) is contributing to modest, slightly elevated CAPE
(at or below 500 J/kg), which will support continuation of
convection near and ahead of the front through the morning.
However, given the aforementioned, weakly stable boundary layer, and
flow aloft aligned roughly along the front/convective band, severe
potential should continue to remain limited/local. As such, current
indications are that WW 551 can be allowed to expire at 10Z, with a
new WW not required to cover very limited, lingering severe risk.
..Goss.. 12/06/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LMK...OHX...PAH...MEG...
LAT...LON 36548970 37058916 37548733 37238695 36798706 36398930
36548970SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 5, 8:06 PM CST | Mesoscale Discussion | SPC | Ballard, Calloway, Carlisle, Crittenden, Fulton, Graves and 5 more | 114 min |
| Dec 5, 8:59 PM CST | Tornado Watch | SPC | Ballard, Caldwell, Calloway, Carlisle, Christian, Crittenden and 16 more | 7 hr |
| Dec 5, 11:28 PM CST | Mesoscale Discussion | SPC | Ballard, Breckinridge, Butler, Caldwell, Calloway, Carlisle and 27 more | 2 hr |
| Dec 6, 5:06 AM CST | Mesoscale Discussion | SPC | Adair, Allen, Barren, Casey, Clinton, Cumberland and 8 more | 114 min |
| Dec 5, 8:54 PM CST | Severe Thunderstorm Watch | SPC | Barry, Christian, Douglas, Dunklin, Howell, McDonald and 6 more | 7 hr |
| Dec 5, 11:17 PM CST | Mesoscale Discussion | SPC | Howell, Ozark | 118 min |
| Dec 6, 3:01 AM CST | Mesoscale Discussion | SPC | Dunklin, Pemiscot | 59 min |
Nearby
Mesoscale Discussions in Kentucky, 2021Mesoscale Discussions in Missouri, 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.