Alert archive / Kentucky / Mesoscale Discussions in 2021

Mesoscale Discussion 2008

December 10, 20219 counties in Kentucky

The Storm Prediction Center issued this mesoscale discussion at Dec 10, 2021, 11:53 PM CST for 9 counties in Kentucky. It was in force for 67 min.

The area

The outline as issued.

The facts

Issued
Dec 10, 2021, 11:53 PM CST (05:53 UTC)
Expired
Dec 11, 2021, 1:00 AM CST
In force
67 min
Issued by
the Storm Prediction Center
Concerning
Tornado watch 554

Counties Breckinridge County, KY, Bullitt County, KY, Grayson County, KY, Hardin County, KY, Jefferson County, KY, Meade County, KY, Nelson County, KY, Shelby County, KY, Spencer County, KY

The radar

The Louisville radar (KLVX), 20 km from the middle of the area, began a volume at 05:55 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, 5.9 hours before the alert went out and 193 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.

027 
ACUS11 KWNS 110553
SWOMCD
SPC MCD 110553 
KYZ000-INZ000-110700-

Mesoscale Discussion 2008
NWS Storm Prediction Center Norman OK
1153 PM CST Fri Dec 10 2021

Areas affected...Portions of northern Kentucky.

Concerning...Tornado Watch 554...

Valid 110553Z - 110700Z

The severe weather threat for Tornado Watch 554 continues.

SUMMARY...A strong tornado threat continues across portions of
northern Kentucky.

DISCUSSION...Storm interference from new cells merging has finally
disrupted the persistent very strong low-level mesocyclone with the
long-lived supercell now entering Breckenridge County, Kentucky.
However, while this has weakened the intensity of the updraft and
low-level rotation, a strong tornado with around 50 to 55 knot Vrot
and a TDS is still present. Mid 60s dewpoints have advected ahead of
this storm and therefore, adequate instability remains for strong
tornado development given the 350 to 400 m2/s2 0-1 km SRH per the
KLVX VWP. Therefore, while circulations may be weaker and more
transient, a strong tornado threat persists.

..Bentley.. 12/11/2021

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

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

LAT...LON   37398619 37398677 37668687 38058635 38438536 38258495
            37808508 37398619

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, 9:48 PM CSTMesoscale DiscussionSPCCaldwell, Graves, Hopkins, 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 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.