Alert archive / Kentucky / Mesoscale Discussions in 2021

Mesoscale Discussion 1999

December 10, 20215 counties in Kentucky

The Storm Prediction Center issued this mesoscale discussion at Dec 10, 2021, 9:48 PM CST for 5 counties in Kentucky. It was in force for 57 min.

The area

The outline as issued.

The facts

Issued
Dec 10, 2021, 9:48 PM CST (03:48 UTC)
Expired
Dec 10, 2021, 10:45 PM CST
In force
57 min
Issued by
the Storm Prediction Center
Concerning
Tornado watch 552...554

Counties Caldwell County, KY, Graves County, KY, Hopkins County, KY, Lyon County, KY, Marshall County, KY

The radar

The Paducah radar (KPAH), 47 km from the middle of the area, began a volume at 03:52 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 00:00Z, 3.8 hours before the alert went out and 175 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.

Skew-T log-pSkew-T log-p diagram, Nashville Metro, TN at 00:00Z on 2021-12-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 182 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Nashville Metro, TN at 00:00Z on 2021-12-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 391 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
182 J/kg
Mixed-layer CIN
-168 J/kg
Mixed-layer LCL
593 m above ground
0-6 km bulk shear
58 kt
0-1 km storm-relative helicity
391 m²/s²
0-3 km storm-relative helicity
370 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.5

Open this sounding in Storm Lab

The text

As transmitted.

196 
ACUS11 KWNS 110349
SWOMCD
SPC MCD 110348 
KYZ000-110445-

Mesoscale Discussion 1999
NWS Storm Prediction Center Norman OK
0948 PM CST Fri Dec 10 2021

Areas affected...Portions of western Kentucky

Concerning...Tornado Watch 552...554...

Valid 110348Z - 110445Z

The severe weather threat for Tornado Watch 552, 554 continues.

SUMMARY...A strong to potentially violent tornado is ongoing and
expected to continue for at least another hour.

DISCUSSION...A strong supercell with a history of a long-track
tornado with intense to potentially violent damage has recently
intensified once again across southwest Kentucky. Latest radar and
environmental analysis give high confidence that an intense to
potentially violent tornado has occurred across southwest Kentucky.
The radar presentation of this storm continues to be extremely
favorable for continued intense, long-lived tornadoes. Nearby
convection has mostly dissipated which may allow a more steady-state
to continue as it moves northeast. The downstream environment
remains very favorable with upper 60s to low 70s dewpoints and
backed surface winds with STP around 5 to 6. Eventually, expect
storm activity to the west to catch this supercell, but until that
happens, continued strong to potentially violent tornadic damage is
expected to continue along its path.

..Bentley.. 12/11/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...PAH...

LAT...LON   36818874 37308804 37518752 37328727 37018769 36638861
            36648879 36688887 36818874

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Dec 10, 6:21 PM CSTTornado WatchSPCAllen, Anderson, Barren, Breckinridge, Bullitt, Butler and 28 more10 hr
Dec 10, 6:22 PM CSTMesoscale DiscussionSPCFulton, Graves, Hickman53 min
Dec 10, 7:41 PM CSTMesoscale DiscussionSPCFulton64 min
Dec 10, 8:35 PM CSTMesoscale DiscussionSPCAllen, Barren, Breckinridge, Bullitt, Butler, Caldwell and 26 more85 min
Dec 10, 8:48 PM CSTMesoscale DiscussionSPCCarlisle, Fulton, Graves, Hickman, Lyon, Marshall57 min
Dec 10, 10:09 PM CSTMesoscale DiscussionSPCBallard, Caldwell, Calloway, Carlisle, Crittenden, Fulton and 7 more96 min
Dec 10, 10:44 PM CSTMesoscale DiscussionSPCCaldwell, Grayson, Hopkins, McLean, Muhlenberg, Ohio61 min
Dec 10, 11:03 PM CSTTornado WatchSPCBallard, Caldwell, Calloway, Carlisle, Christian, Crittenden and 16 more5 hr
Dec 10, 11:08 PM CSTMesoscale DiscussionSPCBoone, Bracken, Campbell, Carroll, Gallatin, Grant and 8 more67 min
Dec 10, 11:20 PM CSTTornado WatchSPCBoone, Bracken, Campbell, Carroll, Gallatin, Grant and 6 more6 hr
Dec 10, 11:28 PM CSTMesoscale DiscussionSPCUnion92 min
Dec 10, 11:36 PM CSTMesoscale DiscussionSPCCalloway, Christian, Logan, Simpson, Todd, Trigg54 min
Dec 10, 11:53 PM CSTMesoscale DiscussionSPCBreckinridge, Bullitt, Grayson, Hardin, Jefferson, Meade and 3 more67 min
Dec 11, 1:02 AM CSTMesoscale DiscussionSPCAdair, Allen, Anderson, Barren, Bath, Bourbon and 51 more88 min
Dec 11, 1:05 AM CSTMesoscale DiscussionSPCBarren, Butler, Edmonson, Green, Hart, Logan and 2 more55 min
Dec 11, 1:27 AM CSTTornado WatchSPCAdair, Allen, Anderson, Barren, Bath, Bourbon and 51 more7 hr
Dec 11, 2:51 AM CSTMesoscale DiscussionSPCBoyle, Casey, Clark, Estill, Garrard, Jessamine and 4 more54 min
Dec 11, 5:32 AM CSTMesoscale DiscussionSPCBell, Breathitt, Clark, Clay, Estill, Jackson and 18 more88 min

Nearby

Mesoscale Discussions in Kentucky, 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.