APRIL NATIONAL TORNADO CLIMATOLOGY

In bringing back my blog, "Caught in the Updraft", here are some graphics c/o NWS Storm Prediction Center data to start off April.

Above is a plot of April tornadoes by year since 1960. The Aprils that standout are the ones with Super Outbreaks. Those would be the  April 3-4, 1974, and April 27-28, 2011.

This is a plot of number of tornadoes by State for the month of April 1950-2018. The only reason 1950-1959 is included is that i honestly could not get Microsoft Access to work for me from 1960-2018 without having to add all 59 years together.  Naturally, Texas, Oklahoma, and Kansas show up being in Tornado Alley. But, notable is the high counts in Illinois compared to Arkansas, Mississippi, and Alabama given the April 2011 outbreak. This could be because of the Palm Sunday outbreak the 11th and 12th of 1965. Illinois was a small part of the 1974 Super Outbreak that included 13 states, but mostly from the lower Great Lakes through the Ohio and Tennessee Valleys, and Mississippi, Alabama, and parts of Georgia.

The distribution of F/EF-Scale values assigned to damage from April tornadoes, again from 1950-2018. Note that those assignments prior to 1977 are estimated since the Fujita Scale was not required for each tornado until that year when the Verification Unit  started as part of the National Severe Storms Forecast Center (now the NWS Storm Prediction Center). There were some tornado damage evaluated prior to 1977, like April 3-4, 1974, but only those done by Fujita and his team and published by Fujita through his works.  Notable is first the 1.77% defined as F-9 or unknown. Around 73% are considered weak tornadoes causing F/EF0 or F/EF1 damage. The remaining 27% being assessed as strong or violent.

Which brings us to tornado fatalities, again from 1950-2018. Deaths, of course, occur with the more violent tornadoes (F/EF 4 and 5) with 72% and nearly 98% occurring with damage rated F/EF2 or greater.