WHY TORNADOES FORM
The warm weather and moist air move north from the Gulf of Mexico
toward Nebraska. The jet stream goes through the Great Plains near
Nebraska and pulls down cool air from the north. The moist air and
cool air collide, starts to spin around and keeps going until it
forms a tornado. Nebraska is in the middle of this. Also, we get a
lot of tornadoes here for these other reasons:
The jet stream can enhance tornadoes' growth making them more
violent, and making new storms. The jet stream is a high--with wind
speeds up to 155 mph, generally from west to east around the earth,
about three miles up and higher. A curving jet stream is one which
moves from west to east but a curve of wind dips to the south and
then it loops back and forth. When the base of the curve gets over
the warm rising winds it can cause great atmosphere havoc and trigger
many severe thunderstorms and tornadoes.
The most violent tornadoes begin in supercell thunderstorms. A
super cell is a mass five to ten miles in diameter with powerful
lightning and a long-lived intense, rotating updraft. The updraft
feeds energy to the tornado. The speed of a tornado can reach up to
150 mph.
But the spinning air inside is still not enough to get this
beginning tornado to the ground-more is needed. Dry air flowing from
the west complicates things as it moves into the storm and begins to
evaporate in the clouds. This causes downdrafts in the western part
of the storm.
All of this which leads to a tornado.