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With the aftermath of one of the biggest outbreaks of tornadoes in the Midwest we have seen in the last 50 years, it made me think of the Valley's vulnerability to a tornado outbreak. Now of course, Virginia's tophogrpahy is completely different than the land in the Midwest. States in the Midwest are prone to tornadoes due to its flat layout and also how the middle of the United States is wedged between warm air from the Gulf of Mexico and cold arctic air flowing south from Canada. May is peak season for tornadoes in the Midwest due to how these air masses flow during that particular month. As for Virginia, our peak season for tornadoes is July in which we experience most of our dangerous thunderstorms. However, no tornado deaths have occurred in Virginia in July. Most of July's tornadoes tend to be weak (91% are EF0 or EF1). Tornado deaths in Virginia peak in the late spring and again in the fall. While not as many tornadoes occur during those months, those that do, tend to be stronger and therefore have a greater potential to be deadly. Some areas in Virginia do appear slightly more prone than others. It is believed that this is caused by topographical influences on thunderstorms such as the change in low-level wind flow and humidity caused by the orientation of the mountains and the Chesapeake Bay.
A tornado is a column of rapidly rotating wind that extends from a thunderstorm cloud to the ground. It often appears as a funnel shaped cloud or a spiraling column of debris. Tornadoes may be only several yards across, or in rare cases, over a mile wide. Winds within a tornado can reach speeds over 250 mph, but most tornado winds are 100 mph or less. Weak tornadoes (EF0-EF1) often last only a minute before dissipating. Strong tornadoes (EF2-EF3) may stay on the ground for 30 minutes or more traveling 20 or even 50 miles. The rare, violent tornado (EF4-EF5) can last hours and travel over a hundred miles. The longest track tornado on record occurred on March 18, 1925 and is known as the "Tri-State Tornado". It cut a swath of damage across the Upper Mississippi Valley for three and a half hours. It traveled 219 miles, killed 695 people and injured over 2000. Fortunately, only one percent of thunderstorms produce tornadoes and only two percent of those are classified as violent (winds over 200 mph).
Now from 1950 to 2001, 376 tornadoes were documented in Virginia. That is an average of 7 tornadoes per year. Nationally, statistics have suggested that prior to 1990, only a third of all tornadoes were actually recorded. Many occurred in unpopulated areas or caused little property damage and therefore are not reported to the National Weather Service. Others may have been recorded as wind events instead of tornadoes. Based on these statistics, the actual average number of tornadoes that Virginia likely experiences in a year is between 15 and 20. Tornado fatality records began in 1916 and since then only 65 people have been known to have died from tornadoes in Virginia. A third of these deaths occurred during a tornado outbreak on May 2, 1929, Virginia's worst tornado outbreak.
All records were nearly broken on August 6, 1993 when one deadly tornado killed four and injured 238 people. It was the first recorded violent tornado in Virginia since 1950. Maximum winds were estimated up to 225 mph from damage in downtown Petersburg. From 1950 until 1993 (44 years), only 192 tornado injuries had been recorded. That one tornado more than doubled that number. In just four hours, 18 tornadoes struck. 1993 went on to record 29 tornadoes for the year breaking the old record of 22 set in 1975. The least active year on record was 1982 with only one tornado reported.
Tornadoes IN YOUR COMMUNITY!
Although we are in the Valley, hills and/or mountains do NOT offer protection. The greatest example of this is seen in Wyoming, the Teton Wilderness which is about 45 northeast of Jackson, Wyo. On July 21, 1987, an F-4 tornado went over mountains as high as 10,000 feet, blowing down mostly mature lodgepole pines from 80 to 100 feet tall, as noted by Thomas P. Grazulis in his book Significant Tornadoes 1680-1991.
April 28, 2002: A severe weather episode that culminated in the deadly F4 La Plata, MD tornado produced 4 tornadoes in Virginia. The most significant tornadoes affected Shenandoah, Bedford and Campbell counties. In Shenandoah county, an F2 tornado injured 2 people, destroyed 4 homes, damaged 56 additional homes and 36 agricultural structures, downed numerous trees, and blew over a tractor-trailer on Interstate 81.
September 8, 2004 – Clarke County – Intensity (F0)
September 17, 2004 – Warren County – Intensity (F0)
September 17, 2004 – Frederick County – Intensity (F2)
September 17, 2004 – Frederick County – Intensity (F1)
Tornadoes by County, 1950-2005
Most tornadoes in Virginia have been in Loudoun County with 22. The second highest on the list is Faquier County with 18 tornadoes.
With this in mind, let's be aware the tornadoes do happen in the Shenandoah Valley and it is a great idea to have a plan with you and your family as such events occur. Nationally, the US. averages over 800 tornadoes per year. Tornadoes can strike anywhere in the US. during any month and any time of day. Virginia has seen as few as one tornado in a year (1982) to as many as 29 tornadoes (1993). Tornadoes have occurred during every month and every hour of the day. It can happen here. It could happen to you. Be prepared by knowing what to do when a tornado threatens.