Event Overview
A strong low pressure system over the Mississippi Valley region combined with high pressure over New England to produce high winds over the southern Appalachian Mountains. There were numerous reports of damage from the winds throughout the mountains of East Tennessee, southwest Virginia, and southwest North Carolina, especially in the Great Smoky Mountains.

Image 1: Image 1 is an image of radial velocity from the KMRX radar, located at the NWS office in Morristown. Bright green colors indicate strong winds moving toward the radar. In southern Sevier County, there are streaks of higher velocities, which is where the winds are being channeled between the mountain peaks (the black areas within the green are where the radar beam intersects the mountain peaks). Radar estimates of wind speed in this area are around 70 mph. (Click image for full resolution)

 

Image 2: Image 2 is a vertical profile of winds with time at the KMRX radar. At 1049 UTC (left side of the image), wind speeds at 3000 ft were estimated at 40 kts (about 46 mph), and 60 kts (70 mph) at 5000 ft. (Click image for full resolution)

Damage Reports
Here are some of the damage reports from county law enforecement offices:

WISE COUNTY VA...FROM 10 PM TO 8 AM...TREES AND POWER LINES DOWN ACROSS THE HIGHEST ELEVATIONS.
POLK COUNTY TN...OVERNIGHT TIL 730 AM...TREES AND POWER LINES DOWN COUNTY WIDE.
MONROE COUNTY TN...1030 PM TIL 730 AM...TREES AND POWER LINES DOWN ACROSS THE HIGHER ELEVATIONS ESPECIALLY TELLICO PLAINS.
CHEROKEE COUNTY NC...OVERNIGHT TIL 11 AM...TREES AND POWER LINES DOWN ACROSS THE HIGHEST ELEVATIONS.
BLOUNT COUNTY TN...OVERNIGHT TIL 930 AM...NUMEROUS TREES AND POWER LINES DOWN...ESPECIALLY IN TOWNSEND AND THE CADES COVE AREA.
GREAT SMOKY MOUNTAINS NATIONAL PARK...MOST ROADS CLOSED DUE TO TREES DOWN...ON THE TENNESSEE SIDE OF THE SMOKYS.
SEVIER COUNTY TN...OVERNIGHT TIL 1030 AM...TREES AND POWER LINES DOWN ACROSS THE HIGHER ELEVATIONS ESPECIALLY THE SMOKIES.
COCKE COUNTY TN...3 AM TIL 730 AM...TREES AND POWER LINES DOWN ACROSS THE HIGHER ELEVATIONS.
GREENE COUNTY TN...OVERNIGHT TIL 930 AM...TREES AND POWER LINES DOWN ACROSS THE SOUTHEAST HALF OF THE COUNTY.
UNICOI COUNTY TN...OVERNIGHT TIL 8 AM...TREES AND POWER LINES DOWN COUNTYWIDE.
CARTER COUNTY TN...5 AM TIL 9 AM...TREES AND POWER LINES DOWN COUNTYWIDE.
JOHNSON COUNTY TN...JUST A FEW POWER OUTAGES.
RUSSELL COUNTY VA...OVERNIGHT TIL 7 AM...FEW TREES AND POWER LINES DOWN.

Here are some measured wind speeds across the area:

COVE MOUNTAIN FIRE TOWER IN GATLINBURG REPORTED A GUST TO 71 MPH.
COKER CREEK FIRE TOWER IN SOUTHERN MONROE COUNTY REPORTED A GUST TO 69 MPH.
AN OBSERVER IN TELLICO PLAINS REPORTED A WIND SPEED OF 55 MPH.
IN UNICOI COUNTY...A GUST WAS MEASURED TO 44 MPH.

Image 3: Image 3 is a vertical profile of temperature, dewpoint, and winds from Atlanta in the morning. At about 2000 ft, the temperature begins to increase with height. It is at this level that winds increase rapidly, up to 55 kts (65 mph). Winds just below this level were only 10 kts (about 12 mph). (Click image for full resolution)

 

What Caused the Damaging Winds
A strong low pressure system over the Mississippt Valley and high pressure over New England combined to produce a tight pressure gradient across the area. This led to a strong winds of 50 to 60 mph in the low levels of the atmosphere, but just above the surface. As these southerly winds encountered the higher elevations of the Smoky Mountains, they were channeled between the mountains, which helped to speed the winds up even more. However, at lower elevations of the Tennessee Valley, winds were light or nearly calm through the day. This rapid increase of wind speed with height created very strong wind shear, which is a serious hazard for aircraft.