The Union County Landspout
9 June 2001
Bryan P. McAvoy
NOAA/National Weather Service
A weak tornado touched down near Carlisle, South Carolina, on 9 June 2001. Image taken by Tony Henderson.
Author's Note: The following report has not been subjected to the scientific peer review process.
During the afternoon of June 9, 2001, a weak tornado occurred
in southern Union County, South Carolina. The tornado touched
down around 330 pm EDT (1930 UTC), about 3 miles west southwest
of Carlisle, in the heart of the Sumter National Forest, and
dissipated a few minutes after 4 pm. The damage path was never
surveyed, but local fire and rescue reported some minor tree
damage where the tornado went into the woods.
When we say "tornado", we do not mean the classic supercell
tornado, which forms over a depth of thousands of feet and can
produce catastrophic damage. In this case, the tornado was one
that is usually classified as a "landspout". The phrase is
derived from the more common "waterspout" which is a weak
tornado that forms over water, and is seldom if ever associated
with a parent mesocyclone.
In the case of the Union County tornado, it occurred in a fairly
typical landspout environment. The associated convection was
very weak, not more than a moderate shower. The radar four
panels (Fig. 1) show the reflectivity pattern from 0.5, 1.5,
2.4 and 3.4 degree elevation scans. In other words, these images
were taken at the same time, but at different elevations in the
storm. Notice how small and weak the cell is. The storm top,
in the fourth panel (lower right), does not even extend to
20,000 feet, and these images represent the storm at its
strongest. The storm relative velocity data from the same time
(Fig. 2) show no organized areas of rotation, nor any strong
storm top divergence.
Figure 1. KGSP radar reflectivity at 1948 UTC 9 June 2001 at
0.5 degrees (upper left), 1.5 degrees (upper right), 2.4 degrees
(lower left), and 3.4 degrees (lower right).
Figure 2. As in Fig. 1, except for Storm Relative Motion.
This is typical of a landspout as all the dynamics for the
tornado occur very low in the atmosphere, below the cloud base.
As a result, the Weather Surveillance Radar (WSR-88D) at the
National Weather Service office at the GSP airport could not
effectively scan these features, as they occur too low in the
atmosphere and on too small a scale for the beam to detect
them at long range.
But, there most definitely was a tornado. Witnesses watched
the landspout for nearly 30 minutes. In fact one witness,
Tony Henderson, even took pictures (Fig. 3).
Figure 3. Image of weak tornado over Union County, South
Carolina, near Carlisle. Image taken by Tony Henderson.
During its life, the landspout was nearly stationary, drifting
only slowly to the southeast. This is a typical characteristic
of landspouts. Landspouts are usually stationary as they form
in a weakly sheared environment, which is anathema to other
types of tornado production. Witnesses said there was very
little rain and no lightning and thunder, another landspout
characteristic. The evening sounding from nearby Greensboro,
North Carolina, had weak lower tropospheric shear, though winds
Essentially, a landspout forms when a broad, weak area of
cyclonic or anticyclonic rotation in the low levels of the
atmosphere is caught up in the updraft of a developing cumulus
cloud. The effect is similar to that of a figure-skater pulling
in her arms to spin faster. As the area of rotation is stretched
and constricts, it rotates faster, until condensation occurs and
the funnel become visible. In this case, the landspout was
frequently in contact with the ground. Thus, by definition,
it was a tornado.