Fig 1.
County population in 2012.
Fig 2.
Annual number of tornadoes (1970–2015) over the states used in the long-term view model.
The blue line is a 2nd-order local polynomial regression smoother (span = .75) and the gray band is the 95% uncertainty range on the smoother.
Fig 3.
Number of tornadoes 1970–2015 (left) and number of days with at least one tornado.
Fig 4.
Annual tornado counts over the period 2000–2015 in two degree raster cells.
A count is added to a cell if a tornado track intersects it.
Fig 5.
Time series (1954–2015) of the four predictors used in the short-term view model.
The blue line is a 2nd-order local polynomial regression smoother (span = .75) and the gray band is the 95% uncertainty range on the smoother.
Fig 6.
Expected annual tornado (EF0+) occurrence rates per 100 square kilometers. The data cover the period from 1970–2015.
Fig 7.
Standard deviation of tornado occurrence per 100 square kilometers.
Fig 8.
Distribution of the modified probability integral transform values.
The values have a distribution that looks uniform.
Fig 9.
Raw versus expected tornado rates.
The best-fit regression line is shown in red.
Fig 10.
Expected annual tornado (EF1+) occurrence rates per 100 square kilometers.
Fig 11.
ENSO effect on tornadoes. Magnitude of the effect in units of percentage change in tornado rate per standard deviation (s.d.) increase in the springtime (Mar–May) value of the bi-variate ENSO index. Positive values indicate more tornadoes during El Niño.
Fig 12.
Significance of the ENSO effect on tornadoes in units of standard deviation.
Fig 13.
NAO and WCA effect on tornadoes.
(A) Magnitude of the NAO effect in units of percentage change in tornado rate per s.d. increase in the springtime (Apr–Jun) value of the NAO index. Negative values indicate fewer tornadoes with a positive NAO. (B) Magnitude of the WCA effect in units of percentage change in tornado rate per °C increase in February SST in the Western Caribbean Sea.
Fig 14.
Hindcast of the 2011 tornado year.
The straight-line tracks of all tornadoes during that year are shown in white.