April Tornadoes

April 2011 is likely going down as one of the most active months for tornadoes. One has to wonder what May will hold. May is the month with the most tornadoes reported on average as this chart shows.

Could May 2011 be another active month for tornadoes? Let’s see.

Two-tailed p value: 0.004
Pearson’s R statistic: 0.363
Degrees of Freedom (df): 58

From the chart and correlation outcome, there is a correlation between April and May tornado activity. The more tornadoes reported in April, the more likely May will be just as active. The p-value is below 0.05, so there is a significant correlation. This is rather concerning that America has been ravaged by tornadoes in this very active April, especially in the Southeast and Midwest.

Now, one has to wonder if an active April means that if a tropical storm, hurricane, or major hurricane will make landfall on America.

April Tornadoes and US Tropical Cyclone Landfall

Two-tailed p value: 0.290
Pearson’s R statistic: 0.139
Degrees of Freedom (df): 58

April Tornadoes and US Major Hurricane Landfall

Two-tailed p value: 0.993
Pearson’s R statistic: -0.001
Degrees of Freedom (df): 58

There is a correlation between April tornadoes and US landfall, but since the p-value is above 0.05, it is not significant. On the other hand, there is no correlation with April tornadoes and US major hurricane landfall.

Now, let’s look at spring, which is from March to May and see if there is a correlation between number of tornadoes in spring and tropical storm, hurricane, or major hurricane will make landfall on America.

Spring Tornadoes and US Tropical Cyclone Landfall

Two-tailed p value: 0.019
Pearson’s R statistic: 0.303
Degrees of Freedom (df): 58

Spring Tornadoes and US Major Hurricane Landfall

Two-tailed p value: 0.972
Pearson’s R statistic: 0.005
Degrees of Freedom (df): 58

There is a significant correlation between Spring tornado activity and tropical cyclones making landfall. The p-value is below 0.05, which there is a significant relationship between Spring tornadoes and tropical cyclones making landfall. On the other hand, there is no correlation between Spring tornado activity and major hurricanes making landfall on America. The correlation is slightly positive, but not significant. What does this mean? America may see tropical cyclones making landfall this upcoming hurricane season.

The last time we had a year this active tornado season was in 2008. The 2008 Atlantic Hurricane Season was a devastating year for America. Tropical cyclones made landfall on the US back-to-back starting with Dolly and ending with Ike. Texas got most of the landfall; Dolly, Edouard, and Ike. Ike was the worst of the 2008 hurricane and third most costliest after Katrina and Andrew.

Keep in mind that correlation does not equate with causation. Just because we have an active tornado season does not always mean that May will be active or US is going to see tropical cyclones making landfall. Sometimes, if spring is not active, US could see more tropical cyclones making landfall than in spring that is active.

Source of data is from NOAA-Storm Prediction Center WCM Page

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