sounds believable at first. The idea is that tornadoes bring such a drop in atmospheric
pressure that the higher pressure inside your home will make it explode unless you
open all the windows. Luckily for homeowners, there's no truth to this. Unless you live
in a downed spaceship, your house probably has enough venting to avoid explosion. All
opening the windows will accomplish is making it a little easier for debris to hit you
while the storm is rolling through.
Each year, about a thousand tornadoes touch down in the United States, far more than
any other country.
Waterspouts are tornadoes that form over a body of water.
Usually a tornado starts off as a white or gray cloud but if it stays around for a while, the
dirt and debris it sucks up eventually turns it into black one.
3 out of every 4 tornadoes in the world happen in the United States.
Tornado winds are the fastest winds on Earth.
In 1931 a tornado in Mississippi lifted an 83 ton train and tossed it 80 feet from the
Some tornadoes make a considerable amount of noise while others make very little. It
depends on the objects a tornado might hit or carry. A tornado moving along an open
plain may make very little noise.
In the northern hemisphere tornadoes usually rotate in a counterclockwise direction.
As far as we can tell, there are only two people on record that claim to have been in the center
of a tornado and lived. Not surprisingly, both of them were farmers. The first man was Will
Keller, from Greensburg, Kan.
On June 22, 1928, Mr. Keller was with his family, checking out the damage to his wheat crop
from a hailstorm that had just passed. He spotted an umbrella-shaped cloud in the near distance
and had a feeling that a tornado might develop. Before he knew it, there were three funnel
clouds heading his way in a hurry. Keller rushed his family to their storm cellar and, before
climbing in himself, decided to take another look. He'd seen many tornadoes over the years, so
he wasn't afraid, but remained cautious. Kellar said he was transfixed by the twister, and he held
his position until it was directly overhead.
Once inside the swirling cloud, Keller said that everything was "as still as death." He reported
smelling a strong gassy smell and had trouble breathing. When he looked up, he saw the circular
opening directly overhead, and estimated it to be roughly 50 to 100 feet in diameter and about
a half a mile high. The rotating cloud walls were made clearly visible by constant bursts
of lightning that "zigzagged from side to side." He also noticed a lot of smaller tornadoes
forming and breaking free, making a loud hissing noise. The tornado then passed, skipping over
his house and smashing the home of his neighbor.
The second account from Roy Hall does nothing to disprove Keller's story. Hall was a soybean
farmer in McKinnet, Texas. One spring afternoon in 1951, Hall and his family were outside when
a nasty storm approached. He sent his wife and kids inside to hide under a bed but stayed to
watch the coming storm. He claims to have seen green sheets of rain just before the tornado
formed. After baseball-sized hail started coming down, he went inside. He then heard a loud
rumbling followed by complete silence. The walls began to shake, and to his surprise, his roof
was ripped away and thrown into the woods nearby. At this point, he looked up to find the
tornado directly overhead. He described the inside as a smooth wall of clouds, with smaller
twisters swirling around the inside before breaking free. Once again, non-stop lightning created
a bluish light, enabling him to see everything clearly. And then, just like that, the tornado passed
and the sky turned sunny. The same storm killed 100 Texans, but Hall and his family survived.
Q. What is a supercell thunderstorm?
A supercell is an organized thunderstorm that contains a very strong, rotating updraft. This
rotation helps to produce severe weather events such as large hail, strong downbursts, and
tornadoes. Supercells usually form isolated from other thunderstorms because it allows the
storm more energy and moisture from miles around. These storms are relatively rare, but
always a threat to life and property.
A tornado begins as a rotating, funnel-shaped cloud extending from a thunderstorm cloud base,
which meteorologists call a funnel cloud. A funnel cloud is made visible by cloud droplets,
however, in some cases it can appear to be invisible due to lack of moisture. A funnel cloud is
not affecting the ground. If the funnel extends far enough down to begin affecting the ground,
then it becomes a tornado.
Tornado paths range from 100 yards to one mile wide and are rarely more than 15 miles long,
State Tornado of 1925. They can last from several seconds to more than an hour, however, most
don't exceed 10 minutes. Most tornadoes travel from the southwest to northeast with an
average speed of 30 mph, but the speed has been observed to range from almost no motion to
Q. When and where do tornadoes occur?
Most tornadoes occur in the deep south and in the broad, relatively flat basin between the
Rockies and the Appalachians, but no state is immune. Peak months of tornado activity in the
U.S. are April, May, and June. However, tornadoes have occurred in every month and at all
times of the day or night. A typical time of occurrence is on an unseasonably warm and sultry
Spring afternoon between 3 p.m. and 9 p.m.
Not necessarily, for any of those. Rain, wind, lightning, and hail characteristics vary from storm
to storm, from one hour to the next, and even with the direction the storm is moving with
respect to the observer. While large hail can indicate the presence of an unusually dangerous
thunderstorm, and can happen before a tornado, don't depend on it. Hail, or any particular
pattern of rain, lightning or calmness, is not a reliable predictor of tornado threat.
The details are still debated by tornado scientists. We do know tornadoes need a source of
instability (heat, moisture, etc.) and a larger-scale property of rotation (vorticity) to keep going.
There are a lot of processes around a thunderstorm which can possibly rob the area around a
tornado of either instability or vorticity. One is relatively cold outflow--the flow of wind out of
the precipitation area of a shower or thunderstorm. Many tornadoes have been observed to go
away soon after being hit by outflow. For decades, storm observers have documented the death
of numerous tornadoes when their parent circulations (mesocyclones) weaken after they
become wrapped in outflow air--either from the same thunderstorm or a different one. The
irony is that some kinds of thunderstorm outflow may help to cause tornadoes, while other
forms of outflow may kill tornadoes.
Q. Do tornadoes really skip?
Not in a literal sense, despite what you may have read in many older references, news stories,
or even damage survey reports. By definition (above), a tornado must be in contact with the
ground. There is disagreement in meteorology over whether or not multiple touchdowns of the
same vortex orfunnel cloud mean different tornadoes (a strict interpretation). In either event,
stories of skipping tornadoes usually mean
There was continuous contact between vortex and ground in the path, but it was too
paths (very common before the 1970s); or
There were multiple tornadoes with only short separation, but the survey erroneously
Tornadoes can last from several seconds to more than an hour. The longest-lived tornado in
history is really unknown, because so many of the long-lived tornadoes reported from the early-
mid 1900s and before are believed to be tornado series instead. Most tornadoes last less than
Q. What is a waterspout?
A waterspout is a tornado over water--usually meaning non-supercell tornadoes over water.
Waterspouts are common along the southeast U. S. coast--especially off southern Florida and
the Keys--and can happen overseas, bays and lakes worldwide. Although waterspouts are always
tornadoes by definition; they don't officially count in tornado records unless they hit land. They
are smaller and weaker than the most intense Great Plains tornadoes, but still can be quite
dangerous. Waterspouts can overturn boats, damage larger ships, do significant damage when
hitting land, and kill people. The National Weather Service will often issue special marine
warnings when waterspouts are likely or have been sighted over coastal waters, or tornado
warnings when waterspouts can move onshore.
Not necessarily. There is a statistical trend (asdocumented by NSSL's Harold Brooks) toward
wide tornadoes having higher damage ratings. This could be related to greater tornado strength,
more opportunity for targets to damage, or some blend of both. However, the size or shape
of any particular tornado does not say anything conclusive about its strength. Some small "rope"
tornadoes still can cause violent damage of EF4 or EF5; and some very large tornadoes over a
quarter-mile wide have produced only weak damage equivalent to EF0 to EF1.
Q. Can't we weaken or destroy tornadoes somehow, like by bombing them or sucking out
their heat with a bunch of dry ice?
The main problem with anything which could realistically stand a chance at affecting a tornado
(e.g., hydrogen bomb) is that it would be even more deadly and destructive than the tornado
itself. Lesser things (like huge piles of dry ice or smaller conventional weaponry) would be too
hard to deploy in the right place fast enough, and would likely not have enough impact to affect
the tornado much anyway. Imagine the legal problems one would face, too, by trying to bomb
or ice a tornado, then inadvertently hurting someone or destroying private property in the
process. In short--bad idea!
Nobody knows, for certain. There is no proof that seeding can or cannot change tornado
potential in a thunderstorm. This is because there is no way to know that the things a
thunderstorm does after seeding would not have happened anyway. This includes any presence
or lack of rain, hail, wind gusts or tornadoes. Because the effects of seeding are impossible to
prove or disprove, there is a great deal of controversy in meteorology about whether it works,
and if so, under what conditions, and to what extent.
Q. I've heard about tornadoes picking up objects and carrying them for miles. Does this
happen? Who does research on it?
Yes, numerous tornadoes have lofted (mainly light) debris many miles into the sky, which was
then blown by middle- and upper-atmospheric winds for long distances. The vertical winds in
face to the wind or flat sides (like roofs, walls, trees and cars), and are strong enough to carry
lightweight objects tens of thousands of feet high. Though the heaviest objects, such as railroad
cars, can only be airborne for short distances, stories of checks and other papers found over 100
miles away are often true. The Worcester MA tornado of 9 June 1953 carried mattress pieces
high into the thunderstorm, where they were coated in ice, before they fell into Boston Harbor.
Pilots reported seeing debris fluttering through the air at high altitude near the thunderstorm
which spawned the Ruskin Heights MO tornado of 20 May 1957. There is a research group at the
University of Oklahoma which studies tornado debris flight. If you personally know of a case of
tornado debris carried long-distance, they have a hotline you can call to report it.
The "Tri-state" tornado of 18 March 1925 killed 695 people as it raced along at 60-73 mph in a
219 mile long track across parts of Missouri, Illinois and Indiana, producing F5 damage. The
death toll is an estimate based on the work of Grazulis (1993); older references have different
counts. This event also holds the known record for most tornado fatalities in a single city or
town: at least 234 at Murphysboro IL. The deadliest of the modern era (since 1950) was on 22
May 2011, when a large EF5 tornado crossed Joplin, MO, causing 158 direct fatalities. The 25
deadliest tornadoes on record are listed here. We also have web links related to this and other
major tornado events.
Q. What was the biggest known tornado to hit the United States?
The Hallam, Nebraska F4 tornado of 22 May 2004 is the newest record-holder for peak width, at
nearly two and a half miles, as surveyed by Brian Smith of NWS Omaha. This is probably close to
the maximum size for tornadoes; but it is possible that larger, unrecorded ones have occurrer.
Recent trends indicate around 1300, give or take a few hundred per year. The actual average is
unknown, because tornado spotting and reporting methods have changed so much in the last
several decades that the officially recorded tornado climatologies are believed to be incomplete.
Also, in the course of recording thousands of tornadoes, errors are bound to occur. Events can
be missed or misclassified; and some non-damaging tornadoes in remote areas could still be
Q. How many people are killed every year by tornadoes? How do most deaths happen in
On average, tornadoes kill about 60 people per year--most from flying or falling (crushing)
debris. The actual number of tornado deaths in a year can vary wildly -- from single digits to
hundreds, depending on many factors from both weather and society.
Tornado season usually means the peak period for historical tornado reports in an area, when
averaged over the history of reports. There is a general northward shift in "tornado season" in
the U. S. from late winter through mid summer. The peak period for tornadoes in the southern
plains, for example, is during May into early June. On the Gulf coast, it is earlier during the
spring; in the northern plains and upper Midwest, it is June or July. Remember: tornadoes can
periods for your area, Harold Brooks of NSSL has prepared numerous tornado probability