National
Geographic: The tornado that devastated Tuscaloosa,
Alabama, on Wednesday was the result of an unusual confluence
of meteorological conditions. Current estimates put the
twister's wind speed at about 260 mph, and it may have remained
in contact with the ground for more than 200 miles. An
unusually strong jet stream over the region, with wind speeds
of 150 mph, caused intense upward motion in the atmosphere. The
colder, drier air within combined with the warm, moist air
already in place to create rotating thunderstorms known as
supercells—one of the few types of storms that spawn
tornadoes. A 50 mph wind closer to the ground only increased
the storms' rotation. Wednesday's tornado outbreak included
more than 100 twisters across 6 states and killed at least 283
people, making it the worst outbreak since 3 April 1974, when
330 people were killed in an area that stretched from Alabama
to Indiana.
