Witness: Tornado Swarm 2011
April 2011 was the Most Violent Month of Tornadoes on Record



 
Witness: Tornado Swarm 2011
April 2011 was the Most Violent Month of Tornadoes on Record

 
2011 has been an exceptionally destructive and deadly year for tornadoes; worldwide, at least 566 people perished due to tornadoes: 12 in Bangladesh and one in New Zealand, one in the Philippines, one in Russia, one in Canada and an estimated 550 in the United States (compared to 564 US deaths in the 10 years prior combined).

Due in large part to several extremely large tornado outbreaks in the middle and end of April and in late May, the year is currently on near-record to record pace, with six EF5 tornadoes as of July 6.



April 2011 was the most violent month of tornadoes on record, and the deadliest in modern times.

The 'super outbreak' of April 26-27 alone involved more than a hundred separate twisters, killing over 300 people and cutting a swath of destruction across the south.

Using dozens of amateur and professional sources, Witness tells the story of this once-in-a-century event, as captured by those who lived through it.


Extremely destructive tornadoes form most frequently in the U.S., Bangladesh and Eastern India, but they can occur almost anywhere under the right conditions.

Tornadoes also appear regularly in neighboring southern Canada during the Northern Hemisphere's summer season, and somewhat regularly in Europe, Asia, and Australia.

As of August 1, there have been 1,692 tornadoes reported in the US in 2011 (of which at least 1,175 were confirmed).

The year 2011 has been an exceptionally destructive and deadly year for tornadoes; worldwide, at least 560 people perished due to tornadoes: 12 in Bangladesh and one in New Zealand, one in the Philippines, one in Russia and an estimated 546 in the United States (compared to 564 US deaths in the 10 years prior combined).

Due in large part to several extremely large tornado outbreaks in the middle and end of April and in late May, the year is currently on near-record to record pace, with six EF5 tornadoes as of July 6.

It is also the deadliest year for tornadoes in the United States since 1936, due mostly to the 324 tornadic deaths that occurred during the April 27 outbreak across the Southeastern United States and the 158 tornadic deaths in the 2011 Joplin Tornado.


An ongoing outbreak at the end of 2010 continued into the first three hours of 2011. During that period seven tornadoes touched down in Mississippi. However, during the remainder of the month, tornadic activity was suppressed by a cold air mass, with nine additional tornadoes - all weak - taking place.

This inactivity continued through much of February before a pattern shift. Two consecutive outbreaks took place on February 25 and 27 – 28, producing a combined 55 tornadoes. Overall, 63 tornadoes were confirmed in the month, ranking it as the fourth-busiest February on record.

Activity in March was split between the start and end of the month, with a total of 75 tornadoes touching down, which ran slightly above average for the month.In early April, a prolific severe weather event produced at least 42 tornadoes among more than 1,200 reports of wind damage, setting the tone for the month.

 
The United States has the most tornadoes of any country, nearly four times more than estimated in all of Europe, excluding waterspouts. 

Although it is reasonable that global warming may affect trends in tornado activity, any such effect is not yet identifiable due to the complexity, local nature of the storms, and database quality issues. Any effect would vary by region.


A nearly continuous series of major tornado outbreaks followed thereafter in the remainder of April, including two extreme multi-day tornado outbreaks that were among the largest in US history (one of them also one of the deadliest and the costliest) and two other large tornado outbreaks, and combined they resulted in an incredibly active month from start to finish.

It was easily the most active month for tornadoes on record and by an extremely large margin the most active April, with over 750 tornadoes touching down.

In an abrupt reversal, the activity did not continue into May (normally the most active month for tornadoes), however, and the first half was remarkably quiet and one of the least active Mays on record as of the middle of the month.

That continued for three weeks until significant severe weather returned on May 21, and an extremely deadly tornado hit the following day in a major outbreak.

The outbreak continued for the next several days, with over 180 confirmed touchdowns, bringing the month of May near average.

The first day of June brought a rare outbreak into Massachusetts, where several tornadoes touched down, some of them fairly destructive. However, another reversal took place afterward and much of June was fairly quiet, with the exception of an active period in the third week that produced a moderate outbreak. July was also relatively quiet for the most part with below normal activity mostly clustered in the northern Plains.