Episode narrative: A strong storm system moved through the eastern half of the United States from December 9th-11th, 2023. The storm system was supported by a broad upper level trough which deepened and amplified over the central and eastern CONUS on December 9th. At the surface, a cold front over the Mississippi Valley on the morning of the 9th gradually moved eastward across Kentucky and Tennessee through the afternoon and evening hours. Ahead of the cold front, low level warm and humid air from the Gulf of Mexico was lifted northward into Middle Tennessee and South Central Kentucky, which when combined with approaching cold air in the mid-levels of the atmosphere, provided enough instability to develop showers and thunderstorms in the pre-frontal environment during the afternoon and evening hours on December 9th.

Although instability was an important ingredient for the development of thunderstorms, the amount of vertical wind shear in the atmosphere was the key factor that gave storms the potential to become strong and severe. While winds near the ground ranged from 10 to 15 mph out of the south and southeast, winds 4000-5000 feet off the ground were 45 to 55 mph out of the southwest. This combination of changing wind direction and increasing wind speed allowed for the development of supercell thunderstorms, which began to form across west and northwest Tennessee just after noon. Storms continued to increase in intensity during the early afternoon hours, with one particular supercell west of Clarksville, Tennessee becoming the primary storm of concern for our area. A tornado formed near the perimeter of Fort Campbell before moving northeast, producing up to EF-3 damage in northern Montgomery County, TN. The cell then crossed into Kentucky in southern Todd County, where it was on the ground for over 13 miles, producing up to EF-2 damage.

The tornado continued into the NWS Louisville County Warning Area near the community of Allensville on the Todd/Logan County line. In Logan County, the tornado remained on the ground for over 22 miles, producing up to EF-2 damage with maximum estimated winds of 115 mph. The tornado barely crossed into far northwestern Simpson County before lifting about 2 miles southeast of Auburn. However, rotation just off the ground within the mesocyclone remained strong, with funnel clouds being observed as the storm passed through extreme northwestern Simpson County and into southwestern Warren County. Ultimately, a second tornado from the same storm touched down on the south side of Bowling Green, producing up to EF-1 damage with maximum estimated winds of 90 mph over a path of around two and a quarter miles.

Later in the evening, a third tornado also touched down in far northern Clay county Tennessee and then moved across the state line into Monroe county Kentucky. This brief EF-1 tornado did most of its damage near the Harlan Crossroads community before lifting.

Tornado event in SIMPSON County, KENTUCKY
Start: 09-DEC-23 14:48:00
End: 09-DEC-23 14:49:00
Direct deaths: 0
Event narrative: The National Weather Service in Louisville conducted a storm damage assessment survey for the Logan County and Simpson County, Kentucky, portion of a long-track EF3 tornado that touched down on Fort Campbell in Montgomery County, Tennessee. 

The tornado tracked east-northeast across the southern part of Todd County, Kentucky and across Logan County before entering Simpson County along Clifford Peart and J Wilson Road where additional barn damage occurred. No additional damage was observed from the tornado beyond Clifford Peart Road. 

In total, a total of 22.82 miles of the 47.75 mile tornado track was in the NWS Louisville warning area.

Tornado event in WARREN County, KENTUCKY
Start: 09-DEC-23 15:07:00
End: 09-DEC-23 15:13:00
Direct deaths: 0
Event narrative: The National Weather Service conducted a storm damage assessment survey in Warren County on the south side of Bowling Green from the storm on Saturday afternoon December 9.

The tornado touchdown was just east of I-165 near Paradise playground. Damage consisted of twisting and topping some trees, with wind speeds of 80 mph, EF0 and then quickly increased to 90 mph, EF1, with uprooted and snapping trees, roof shingle and soffit damage, destroyed a greenhouse, and uprooting more trees on top of home on Smallhouse Rd. Trees were facing from the northwesterly direction to an East northeasterly direction. The tornado's width along Smallhouse Road was 125 yards wide. The tornado was skipping as it went eastward and was very intermittent. The damage in the next subdivision was shingle and gutter related, with yard furniture thrown northeasterly through easterly direction. Wind speeds were 85 mph, EF0, with a width of 75 yards.

The next significant damage was along Three Spring Road consisting of two large metal warehouses having significant roofing damage. Unfortunately, the area was locked and we are unable to fly the drone due to air space restrictions. Wind speeds in this area were 90 mph, EF1, with a width of 70 yards. The tornado was skipping as it crossed Scottsville Road and Interstate 65, and then did significant roofing damage to the Super 8 Hotel on Cumberland Trace Road. Many sections of the galvanized roofing structure were thrown several hundred yards into the trees and up again against apartments. The roofing material was thrown from the north northeast to the easterly direction. Wind speeds in this area were 90 mph, EF1, with a width of 70 yards. The tornado lifted halfway between Cumberland Trace Road and Deer Meadow Avenue.