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Ponca City Emergency Management – Autumn Thunderstorms and Tornadoes

We all accept the possibility of severe thunderstorms and tornadoes in the spring. These weather events are fairly common each April through June. We are less prepared for a “second” severe weather season that takes place in October and November. Fall tornadoes tend to be slightly less strong and violent than those that occur in the spring. About 20% of fall tornadoes are rated F2 or stronger, compared to 28% of spring storms. Catastrophic F4 and F5 storms are rare anytime, but almost always occur in spring severe weather outbreaks. Despite these facts, damaging, deadly tornadoes can happen any time of year.

Several things influence the development of severe weather in the fall. We typically see more extreme temperature swings in the fall, after the extended summer heat. Yet enough warmth and moisture remain in the fall to contribute to the unstable atmosphere that attracts thunderstorms and tornadoes. Add to this the frequent movement of the jet stream during the fall. These things contribute to instability that is required for severe weather to develop. Second season tornadoes are more common in the Gulf Coast states, from Texas to the Carolinas, due to the higher moisture levels. Tropical storms are often responsible for severe weather inland. But as we saw last weekend, tornadoes are possible any month of the year in any state.

Most fall tornadoes in Oklahoma by year:

1970 7 Tornadoes
1998 27 Tornadoes
2001 19 Tornadoes
2000 7 Tornadoes

The worst fall tornado in Oklahoma happened on October 5, 1970. An F4 tornado struck Shawnee and Prague then dissipated in Okfuskee County. That storm killed four people and injured 84
Worst Fall Tornado Outbreaks:

Nebraska — October 5, 2013
Ohio Valley — November 21-23, 1992

  • 105 tornadoes
  • 13 states
  • 26 deaths
  • Total tornadoes’ path length: 1,227 miles

Texas was, perhaps, the hardest-hit state during this outbreak. An F4 tornado destroyed more than 200 homes on Houston’s east side. Three tornadoes were on the ground at one time in
Harris County.

Louisiana — November 23-24, 2004

  • 93 tornadoes
  • 4 deaths
  • States affected: Texas, Louisiana, Alabama, Indiana, Georgia, South Carolina and more.

Alabama was one of the hardest-hit states during this outbreak. The Birmingham Office of the National Weather Service says a tornado that struck Coosa County and the Lake Mitchell area
had a damage path 49.1 miles long and 1,400 yards wide at its widest point.

Ohio — November 9-11, 2002

  • 82 tornadoes
  • 36 deaths
  • 17 states

A tornado destroyed a movie theater in Van Wert, Ohio. The theater manager and staff got more than 50 people out of the theaters and huddled into hallways and restrooms before the tornado struck. No one in the theater was injured.

South states & Ohio — November 23-24, 2001

  • 66 tornadoes
  • 13 deaths
  • Arkansas, Kentucky, Missouri, Indiana, Alabama, and more

Alabama was particularly hard hit with at least four deaths. The Birmingham office of the National Weather Service says there were about a dozen supercells in the Birmingham area.

Midwest & Indiana — October 17-19, 2007

  • 62 tornadoes
  • 5 deaths
  • EF3 tornado

This three-day event covered a wide swath of the U.S. from Florida to Michigan. Deaths were reported in Michigan and Missouri. In Michigan, news reports say a tornado near Flint struck a
home and threw a baby 40 feet. The baby was found unharmed underneath its crib mattress.

Gulf Coast & North — October 26, 2010

  • 24 tornadoes
  • 0 deaths
  • Record-breaking low pressure system over Minnesota

While the Plains, Deep South and Midwest seem to bear the brunt of the worst fall tornadoes, no area is immune to twisters.

Contact: Paula Cain, Emergency Management Director, 767-0380

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