Foundation Beyond Belief in Oklahoma

The Foundation Beyond Belief is collecting monetary donations to provide disaster relief for victims of the devastating tornado in Oklahoma. Do your part and FBB will act as a clearinghouse distributing the money to charities. Go to the donation page to see updates on the crisis response.

In situations like this, the American Red Cross is always a good charity as well. They also maintain a Safe and Well Listing for those with family in the region.

For those of you outside the US, or otherwise out of the loop here, a tornado blasted through the suburbs of Oklahoma City yesterday afternoon. Some early reports estimate the tornado was over a mile at the base (!) and that it covered almost 20 miles during the 40 minutes it existed. Frankly, these are numbers I would have said were impossible just a few days ago. The chaos is such that death tolls and injury reports are unreliable.

  • kessy_athena

    Actually, it’s not unusual for a strong tornado to be a mile across or more. The largest wedge tornadoes can be as large as 2.5 miles in diameter on the ground.

    • Michael

      There has only ever been one tornado recorded at 2.5 miles wide at its base. Even one mile tornadoes are very rare, and this was a 1.3 mile EF5.

      But this was particularly tragic because it hit Oklahoma City and killed 24 people.

      • kessy_athena

        They’re rare in the sense that the vast majority of tornadoes are small and weak, and therefore do little damage and are of little note. However, among strong tornadoes, it’s not uncommon for them to be quite wide.

        There have been 58 F-5 or EF-5 tornadoes in the US from 1950 – 2012. Of those, 7 were more then 1500 yards wide, 9 were 1000 – 1500 yards wide, 26 were 1000 – 500 yards, and only 6 were less then 400 yards.

        Of all US tornadoes 1950 – 2012, there have been 10 that were 3000 yards wide or more

        http://www.tornadohistoryproject.com/tornado/f5/table

        • Michael

          So a tornado of this size occurs about once per decade in the world.

          That’s pretty rare in my mind.

          • kessy_athena

            1.3 miles is 2288 yards. In the US 1950 – 2012, there were 38 tornadoes 2200 yards wide or wider. Unsurprisingly, they’ve been more frequent recently. There was 1 in 2012, 5 in 2011, 4 in 2010, 3 in 2008, 2 in 2007, 2 in 2004, and 1 in 2002. There were 7 in the 1990′s, 6 in the 80′s, 4 in the 70′s, and 3 in the 60′s. This is just for the US, not the entire planet, but since I think the large majority of recorded tornadoes occur in the US, I’ll call that splitting hairs.

            • Michael

              I’m surprised a tornado could exceed a mile in diameter and not be F5.

            • kessy_athena

              So am I. When I looked up the statistics, my first reaction was to wonder what the heck a mile wide F1 would look like, or if it would even be visible…

              I think the Fujita scale is based on the amount of damage done on the ground, so maybe the low F ranking of some of the big ones reflects where they hit rather then the wind speeds? I’m thinking especially with the older ones that might be the case.

              Although there’s also conservation of angular momentum to consider. A tornado with a given energy will be more intense and have higher wind speeds the smaller it is, so maybe that has something to do with it.

            • Michael

              Your tornadoes are ranked by width of damage path, not by actual wind measurements. The Oklahoma City tornado this year had a damage path over two miles wide.

          • dmantis

            It’s not rare at all for engineers and architects. Its actually ridiculously common.

            That equates to a 10% chance in any given year. Most emergency shelters are designed at a minimum to a .2% probability or what is commonly known as a 500 year storm event.

            • Michael

              The fact that people design to protect against rare events does not mean they are not rare. By this logic, hurricanes with the destructive nature of Katrina are “common.”


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