Severe thunderstorms are what produce tornadoes. The same general conditions(warm mist air meeting cool dry air, wind shear, etc.) that can produce tornadoes can also lead to strong to severe thunderstorms, even if those storms don't produce tornadoes. Another factor may be psychological; after such devastating tornadoes people may be more aware of the severity of the storms that come through.
The first known tornado was near Kilbeggan, Ireland on April 30, 1054. It is pretty much certain that tornadoes have been occurring since long before then.
The tornadoes in April of 2011 happened in much the same way that most U.S. tornadoes do, especially since April often sees large numbers of tornadoes. These tornadoes typically arise as storm systems develop along boundaries of contrasting temperature. The storms systems cause cool air from Canada and/or dry air from the Rockies to collide with warm, moist air from the Gulf of Mexico. This causes thunderstorms to develop. Strong upper level winds then create wind shear that sets the storms rotating, giving them the potential to produce tornadoes. As a result of a La Niña that was occurring at the time, North America was struck be a series of powerful storm systems, starting in October of 2010 and continuing through winter until April of 2011. In the winter these storms were primarily blizzards, but when warmer air came in for the spring they started producing severe thunderstorms and tornadoes. Of the 758 tornadoes confirmed in the U.S. in April of 2011, 528 were the result of two storm systems. The first system ignited thunderstorms along a cold front and dry line, producing 178 tornadoes from April 14 until April 16 mostly impacting Oklahoma, the Deep South, and North Carolina. The second system. The second system was the doozy, producing a record 350 tornadoes in the U.S. from April 25 until 28. This culminated on April 27 in the Deep South with a combination of instability and wind shear not seen for decades, a condition extremely favorable for violent tornadoes.
Typically, April is the month that experiences the most violent storms in spring. This is largely due to the increasing warmth and instability in the atmosphere as winter transitions into summer, leading to more frequent severe weather events such as thunderstorms and tornadoes. March can also see storms, but they are generally less intense, while May often sees storms that are more widespread but not necessarily more violent than those in April.
There were 19 tornadoes recorded in the U.S. on April 9, 2011.
There were 85 tornadoes confirmed on April 14, 2012.
Tornadoes in April 2011 killed 363 people.
The months tornado's usually happen are April, May, and June. at this time the lower atmosphere is warming up while the upper atmosphere remains cold. This creates an unstable atmosphere capable of producing strong thunderstorms. The strong upper level winds at this time create wind shear, which further strengthens the storms and gives them the spin they need to produce tornadoes.
Kirsten Storms was born on April 8, 1984.
Kirsten Storms was born on April 8, 1984.
The storm system that produced the killer tornadoes in the Carolinas on April 16, 2011 originated in the west, organizing over Colorado and New Mexico before producing its first tornadoes in Oklahoma and Kansas. The storm system continue eastward, producing tornadoes across the southern states before striking the Carolinas and neighboring states where the worst damage occurred.
There were 758 confirmed tornadoes in the U.S. in April 2011, a record high. Worldwide statistics are not available.
There were no deaths or injuries from the tornadoes of April 11, 2012. Both of the tornadoes in Texas on that date were rated EF0 and such tornadoes hardly ever kill.