National Weather Service United States Department of Commerce

The 19 January 2001 Hart County, Georgia,

F1 Tornado and Microburst

 

NOAA/National Weather Service
Greer, SC

Author's Note: The following report has not been subjected to the scientific peer review process.

1. Evolution of the Event

A mesoscale convective system (MCS) traveled rapidly northeast across Alabama, Georgia, South Carolina and extreme southern North Carolina during the late morning and early afternoon hours of January 19th, 2001. While the line itself was not particularly intense, one segment of the line produced recurrent damage from north central Alabama, to just west of Charlotte, North Carolina. At least two tornadoes were produced by this line segment, one of F2 intensity across the southern suburbs of the Atlanta metro area. The most likely cause of the recurrent damage was a mesoscale area of low pressure which traveled quickly along a cold front over the region. Figure 1 is a surface map, composed about 30 minutes before the damage occurred in Hart County, Georgia. Note that there are two areas of low pressure. One is over the Georgia/Alabama border, and one further east near Athens. The low near Athens is a mesoscale low which was responsible for most of the damage with the event.

Surface fronts and pressure analysis at 18Z on 19 January 2001

Figure 1. Surface map showing observations, sea level pressure, and fronts at 18Z on 19 January 2001. Click on image to enlarge.

There was no signature indicative of a tornado with this event. In fact, the weak bowing segments had not produced damage as they moved across northeast Georgia. Thus, there was little reason to suspect that damage would occur in Hart County, Georgia. In retrospect, the bowing segment was one of the stronger ones observed with the event. However, as the line moved further northeast, no additional damage occurred, even though later images revealed that the bow over Hart County evolved into a well- defined comma-head echo. Most likely the low moved over the shallow surface cold pool across the northern part of Upstate South Carolina, and strong winds could not translate to the ground. A good thing to, as the comma head moved directly across the Greenville-Spartanburg metro area.

KGSP base reflectivity 0.5 degree scan at 1840Z on 19 January 2001

Figure 2. Base reflectivity from the KGSP radar on the 0.5 degree elevation scan at 1840Z on 19 January 2001. Click on image to enlarge.

2. Damage Survey

The next day, a National Weather Service survey team visited the area where damage had been reported. Most of the damage turned out to be confined to a small part of southwest Hart County, Georgia, near the town of Vanna. The accompanying pictures will detail some of the damage and the team's assessment of the event. Figure 3 shows the first damage found from the event. This was on the southwest side of State Highway 17.

Initial damage on 19 January 2001

Figure 3. The initial damage occurred on the southwest side of State Highway 17, where part of the roof was torn off from two chicken houses. Click on image to enlarge.

The rest of the damage was on the northeast side of State Highway 17, just a little north of the town of Vanna. Figure 4 shows debris from one of two new chicken houses that were completely destroyed by strong straight line winds. The straight line winds occurred a little east of the tornado track. The wind speed here was estimated at around 70 mph. The winds and tornado damage affected a small area covering two ridge tops and a shallow valley.

Chicken house destroyed by straight line wind, 19 January 2001

Figure 4. Chicken house destroyed by strong straight line winds. Click on image to enlarge.

Atop the second hill affected by the microburst, another chicken house and several sheds were damaged or destroyed by the winds. Figure 5 shows a larger perspective on the damage atop the second ridge top. Figure 6 is close-up of some of the damage to the second chicken house. Figure 7 shows one of several sheds, barns and small utility structures that were damaged or destroyed on the second ridge top. This particular barn was immediately behind the location from which the preceding two pictures were taken.

Second chicken house destroyed by straight line wind, 19 January 2001

Figure 5. Second destroyed chicken house (middle distance) as well as a large area strewn with debris on the second ridge top. Click on image to enlarge.

Close-up of second chicken house destroyed by straight line wind, 19 January 2001

Figure 6. Close-up of the destroyed chicken house. Click on image to enlarge.

Small barn destroyed by straight line wind, 19 January 2001

Figure 7. Small Barn destroyed by 70 mph straight line winds. Click on image to enlarge.

About 100-200 yards west of the straight line wind damage was an area of damage that appeared to be caused by a tornado estimated at the low end of F1 intensity. Though the pictures do not fully illustrate, the row of trees in Figure 8, located in the shallow valley, was blown over facing almost directly north. Other debris in this area was also blown to the north. There appeared to be convergent damage in this area as there was additional debris blown from southwest to northeast just west of this area. Thus it appears that a tornado, with damage estimated at the low end of F1 intensity, occurred on the northwest side of a strong microburst. Further evidence is lent by Figure 9. A well-constructed brick home was heavily damaged by the tornado. The roof was nearly blown off and one wall fell over. About 200 yards to the east, on the same hill top, is where the straight line wind damage occurred.

Tree damage from F1 tornado, 19 January 2001

Figure 8. Tree damage from the F1 tornado on 19 January 2001. Click on image to enlarge.

Tornado damage to a brick house, 19 January 2001

Figure 9. Brick house heavily damaged by the F1 tornado. Click on image to enlarge.

Acknowledgements

Pat Moore and Neil Dixon converted the case to the standard web page format.