Tornadoes Above Average This Warm Season

 By Will Perry

Meteorologist

 

Across the Blacksburg County Warning Area, the peak season for tornadic activity is late April through June. In 2004, there were no tornadoes reported during this time period. However, things changed in August and September. 11 tornadoes were confirmed across the Blacksburg County Warning Area, with most occurring in September.

 

The reason? An increase in tropical cyclone remnants passing near or across the region. Tropical cyclone remnants can spawn weak F0-F1, to sometimes strong (F2) tornadoes. Most of the time, this happens during the landfall of the tropical system. The north and east quadrants of the storm are prime areas that usually get tornado spin-ups. As the remnants of Frances, Ivan and Jeanne moved near the region, the Blacksburg County Warning area was put in either the northern or eastern sector from the storms center. Nine tornadoes resulted from these three remnants. One tornado touched down 2 miles west northwest of Gold Hill in Buckingham County during the evening of the 8th of September. This weak (F0) tornado produced mainly tree damage.

 

When the remnants of Ivan passed through Western Virginia on September 17th, it spawned 5 tornadoes. The strongest of which was an F2 that moved across a portion of Henry County, Virginia. The F2 struck the CP-Films plant near Fieldale causing extensive damage. Forty vehicles were severely damaged or destroyed. Extensive roof and outside wall damage occurred to the plant, while the inside walls remained standing. Luckily, no one was injured.

 

Then, on September 28th, the remnants of Jeanne moved across North Carolina. One tornado was spawned over southwestern Pittsylvania County in Virginia, near the town of Oak Ridge. The tornado was mainly at the F0 scale level. The nature of the damage was a few downed trees.  Given the extremely moist soil conditions, it would not have taken very strong winds to cause this damage.  The tornado continued in a northerly direction leaving an intermittent F0 damage path of damaged or downed trees.  Over the last 3 miles of the path the damage became continuous and the tornado briefly reached F1 status resulting in the destruction of a single wide trailer home on Hill Creek Road in the town of Dry Fork.  One minor injury occurred to the occupant in this home. On Foxridge Road in Chatham numerous large trees were uprooted and some were snapped.  One of these large trees landed on a newly constructed garage, destroying it.

 

Earlier in August 2004, tropical moisture surging north from Tropical Depression Bonnie intersected a stationary front over Virginia. Thunderstorms moved along this front from the Triad region of North Carolina, northeast into Rockingham County. These storms produced mainly straight-line wind damage as they moved across Rockingham County into southern Pittsylvania County and the city of Danville. However, this storm did spawn a tornado as it moved into northeast Rockingham County near the town of Mayfield, severely damaging one home. A tornado then touched down minutes late in the city of Danville, Virginia, causing substantial damage to commercial buildings. The tornadoes at these locations reached F1 intensity.

 

An average year in the Blacksburg County Warning area, 2 to 4 tornadoes occur. This year we had 11 confirmed reports, with most occurring from tropical cyclone remnants during the month of September.

 

Fujita Scale

 

SCALE

WIND ESTIMATE *** (MPH)

TYPICAL DAMAGE

F0

< 73

Light damage. Some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; sign boards damaged.

F1

73-112

Moderate damage. Peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos blown off roads.

F2

113-157

Considerable damage. Roofs torn off frame houses; mobile homes demolished; boxcars overturned; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground.

F3

158-206

Severe damage. Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off the ground and thrown.

F4

207-260

Devastating damage. Well-constructed houses leveled; structures with weak foundations blown away some distance; cars thrown and large missiles generated.

F5

261-318

Incredible damage. Strong frame houses leveled off foundations and swept away; automobile-sized missiles fly through the air in excess of 100 meters (109 yds); trees debarked; incredible phenomena will occur.