by Bill Evans
A rotating column of rising air, called a mesocyclone, is the key to the long life of a super cell. It gathers in the warm, humid air near the ground and mixes it with the cool, dry air from above. The mesocyclone supplies the spin that strong tornadoes require.
Most Damaging Tornadoes (F5 and EF5) in the U.S. since 1950
This is a list of tornadoes since 1950 which the National Weather Service has rated F5 (before 2007) or EF5 (2007 on—the most intense damage category on the Fujita and Enhanced Fujita damage scales. The tornadoes are numbered in the order they happened since 1950; so the numbers run from the bottom up.
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Most Damaging Tornadoes in U.S. Since 1950
NUMBER
DATE
LOCATION
58
May 24, 2011
El Reno/Piedmont, OK
57
May 22, 2011
Joplin, MO
56
April 27, 2011
Rainsville/Sylvania, AL
55
April 27, 2011
Preston, MS
54
April 27, 2011
Hackleburg/Phil Campbell, AL
53
April 27, 2011
Smithville, MS
52
May 25, 2008
Parkersburg, IA
51
May 4, 2007
Greensburg, KS
50
May 3, 1999
Bridge Creek/Moore, OK
49
April 16, 1998
Waynesboro, TN
48
April 8, 1998
Oak Grove/Pleasant Grove, AL
47
May 27, 1997
Jarrell, TX
46
July 18, 1996
Oakfield, WI
45
June 16, 1992
Chandler, MN
44
April 26, 1991
Andover, KS
43
August 28, 1990
Plainfield, IL
42
March 13, 1990
Goessel, KS
41
March 13, 1990
Hesston, KS
40
May 31, 1985
Niles, OH
39
June 7, 1984
Barneveld, WI
38
April 2, 1982
Broken Bow, OK
37
April 4, 1977
Birmingham, AL
36
June 13, 1976
Jordan, IA
35
April 19, 1976
Brownwood, TX
34
March 26, 1976
Spiro, OK
33
April 3, 1974
Guin, AL
32
April 3, 1974
Tanner, AL
31
April 3, 1974
Mt. Hope, AL
30
April 3, 1974
Sayler Park, OH
29
April 3, 1974
Brandenburg, KY
28
April 3, 1974
Xenia, OH
27
April 3, 1974
Daisy Hill, IN
26
May 6, 1973
Valley Mills, TX
25
February 21, 1971
Delhi, LA
24
May 11, 1970
Lubbock, TX
23
June 13, 1968
Tracy, MN
22
May 15, 1968
Maynard, IA
21
May 15, 1968
Charles City, IA
20
April 23, 1968
Gallipolis, OH
19
October 14, 1966
Belmond, IA
18
June 8, 1966
Topeka, KS
17
March 3, 1966
Jackson, MS
16
May 8, 1965
Gregory, SD
15
May 5, 1964
Bradshaw, NE
14
April 3, 1964
Wichita Falls, TX
13
May 5, 1960
Prague, OK
12
June 4, 1958
Menomonie, WI
11
December 18, 1957
Murphysboro, IL
10
June 20, 1957
Fargo, ND
9
May 20, 1957
Ruskin Heights, MO
8
April 3, 1956
Grand Rapids, MI
7
May 25, 1955
Udall, KS
6
May 25, 1955
Blackwell, OK
5
December 5, 1953
Vicksburg, MS
4
June 27, 1953
Adair, IA
3
June 8, 1953
Flint, MI
2
May 29, 1953
Ft. Rice, ND
1
May 11, 1953
Waco, TX
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* * *
The 17 Deadliest Days In U.S. Tornado History
(Since 1950)
Courtesy Storm Prediction Center; Compiled by Greg Carbin, Roger Edwards, and Joe Schaefer, SPC
Please note that data from 2011 is incomplete.
RANK
BEGINNING DATE
DEATHS
1
May 22, 2011
695
2
April 27, 2011
313
3
April 3, 1974
310
4
April 11, 1965
260
5
March 21, 1952
205
6
June 8, 1953
142
7
May 11, 1953
127
8
February 21, 1971
121
9
May 25, 1955
102
10
June 9, 1953
90
11
May 31, 1985
76
12
May 15, 1968
72
13(tie)
March 3, 1966
58
13(tie)
April 21, 1967
58
15(tie)
April 10, 1979
57
15(tie)
March 28, 1984
57
15(tie)
February 5, 2008
57
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Waterspout: Cousin to the Tornado
National Oceanic and Atmospheric Administration/Department of Commerce; Photographer: Steve Nicklas
A waterspout is a tornado over water. Waterspouts are common along the southeast U.S. coast—especially off southern Florida and the Keys—but they have been seen as far north as New York City, over the Great Lakes, and even off the coast of California. In one season, as many as 390 waterspouts were observed within 50 miles of the Florida Keys, making them far more prevalent than previously thought.
Waterspouts occur over seas, bays, and lakes worldwide. Although waterspouts are tornadoes, they don’t officially count in tornado records unless they hit land. Waterspouts commonly come from rapidly growing cumulus clouds that have not and often do not become thunderstorms. Waterspouts are smaller and weaker than the most intense Great Plains tornadoes, but still can be quite dangerous. They can cause the same type of damage as an EF0 or an EF1. Waterspouts can overturn small boats, damage ships, do significant damage when hitting land, and kill people.
National Oceanic and Atmospheric Administration/Department of Commerce
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br /> What Is the Difference Between a Tornado Watch and a Tornado Warning?
A tornado watch means that approaching weather may produce a tornado. In a tornado watch, you need to be alert to the fact that the weather conditions are favorable for the formation of tornadoes. You need to be prepared to go to a safe shelter or other place of safety if tornadoes do happen or if a warning is issued. This is the time to turn on local TV or radio to get the latest information. You should also make sure your friends and family are aware of the potential for tornadoes in the area.
* * *
Example of a Tornado Watch
URGENT—IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 600
NWS STORM PREDICTION CENTER NORMAN OK
1030 PM EDT WED AUG 15 2007
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
NORTHERN INDIANA
NORTHWEST OHIO
LAKE MICHIGAN
EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 1030 PM UNTIL 400 AM EDT.
TORNADOES…HAIL TO 1 INCH IN DIAMETER…THUNDERSTORM WIND GUSTS TO 70 MPH…AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 40 STATUTE MILES NORTH AND SOUTH OF A LINE FROM 20 MILES SOUTH SOUTHWEST OF VALPARAISO INDIANA TO 65 MILES EAST OF FORT WAYNE INDIANA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU0).
REMEMBER…A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS.
DISCUSSION…SMALL MCS OVER NW IND HAS FORMED IN THE PAST 90 MINUTES ON WRN SIDE OF COLD POOL/MCV ASSOCIATED WITH EARLIER CONVECTIVE SYSTEM. THE MCS SHOULD REMAIN STRONG THROUGH EARLY THURSDAY AND TRACK ESE INTO OH. A Super cell NOW PRESENT ON WRN SIDE OF SYSTEM WILL POSE A THREAT FOR ISOLATED TORNADOES…IN ADDITION TO DAMAGING WET MICROBURSTS/MARGINALLY SVR HAIL…GIVEN HI PWS AND LOW LEVEL WIND FIELD WITH CONSIDERABLE DEGREE OF SPEED/DIRECTIONAL SHEAR. WIND PROFILES MAY ALSO SUPPORT BACK-BUILDING DEVELOPMENT ON WRN SIDE OF MCS…WITH ASSOCIATED LOCALLY HEAVY RAIN POSSIBLE INTO FAR NE IL/NRN IND IN WAKE OF Super cell.
AVIATION…TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM MOTION VECTOR 30030.
…CORFIDI*
* * *
Once the outline of a watch area is defined by the NWS Storm Prediction Center, a list of counties within the watch area is posted to make sure residents and travelers understand exactly which counties are possibly in the path of a future tornado. These watch areas are shown on television by a meteorologist or weathercaster, and the counties are named in a special weather bulletin on radio and television. Many television broadcast or cable channels will scroll the names of the counties across the TV screen in what is called a crawl.
* * *
Example of a Watch County Breakdown
WOUS64 KWNS 160227
WOU0
BULLETIN—IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH OUTLINE UPDATE FOR WT 600
NWS STORM PREDICTION CENTER NORMAN OK
1030 PM EDT WED AUG 15 2007
TORNADO WATCH 600 IS IN EFFECT UNTIL 400 AM EDT FOR THE FOLLOWING LOCATIONS
INC001-003-009-017-033-039-049-053-069-075-085-087
-091-099-103-113-131-141-149-151-169-179-181-183-160800
-/O.NEW.KWNS.TO.A.0600.070816T0230Z-070816T0800Z/
IN
INDIANA COUNTIES INCLUDED ARE
ADAMS
ALLEN
BLACKFORD
CASS
DE KALB
ELKHART
FULTON
GRANT
HUNTINGTON
JAY
KOSCIUSKO
LAGRANGE
LA PORTE
MARSHALL
MIAMI
NOBLE
PULASKI
ST. JOSEPH
STARKE
STEUBEN
WABASH
WELLS
WHITE
WHITLEY
OHC003-039-051-069-125-137-161-171-160800
-/O.NEW.KWNS.TO.A.0600.070816T0230Z-070816T0800Z/
OH
OHIO COUNTIES INCLUDED ARE
ALLEN
DEFIANCE
FULTON
HENRY
PAULDING
PUTNAM
VAN WERT
WILLIAMS
LMZ046-160800-/O.NEW.KWNS
.TO.A.0600.070816T0230Z
-070816T0800Z/CW
ADJACENT COASTAL WATERS INCLUDED ARE
MICHIGAN CITY IN TO NEW BUFFALO MI
* * *
Tornado Warning
A tornado warning is issued when a hook echo is indicated on weather radar. A hook echo is produced when rain, hail, or debris is wrapped around a super cell, indicating that the hook echo that has been sighted could potentially drop down to the ground and become a tornado.
A tornado warning is also issued when an official weather spotter (someone who is trained to detect a tornado with the human eye) sees a funnel cloud and alerts local authorities such as police, sheriff, fire department, or the local National Weather Service office. It can take only a few moments between a funnel cloud being sighted on radar and a tornado touching down. By the time a warning is heard on radio or seen on television, the tornado may already be on the ground.
It’s important to know the details and find out if your county is in the watch area. Have a plan and be ready to act if and when a tornado warning is issued.
How to Save Yourself If You Are Ever Caught in a Tornado
Know the signs of a tornado: Weather forecasting science is not perfect and some tornadoes do occur without a tornado warning. There is no substitute for staying alert to the sky. Besides an obviously visible tornado, here are some things to look and listen for:
Strong, persistent rotation in the cloud base.
Whirling dust or debris on the ground under a cloud base—tornadoes sometimes have no funnel!
Hail or heavy rain followed by either dead calm or a fast, intense wind shift. Many tornadoes are wrapped in heavy precipitation and can’t be seen.
Day or night: Loud, continuous roar or rumble that doesn’t fade in a few seconds like thunder.
Night: Small, bright, blue-green to white flashes at ground level near a thunderstorm (as opposed to silvery lightning up in the clouds). These mean that power lines are being snapped by a very strong wind, maybe a tornado.
Night: Persistent lowering from the cloud base, illuminated or silhouetted by lightning—especially if it is on the ground or there is a blue-green to white power flash underneath.
Frank Picini
Fred K. Smith; used by permission.
Frank Picini
Fred K. Smith; used by permission.
What To Do During A Tornado
In a house with a basement: Avoid windows. Get in the basement and under some kind of sturdy protection like a heavy table or workbench, or cover yourself with a mattress or sleeping bag. Know where very heavy objects rest on the floor above (like pianos, refrigerators, or waterbeds) and do not go under them. They may fall through a weakened floor and crush you.
In a house with no basement, a dorm, or an apartment: Avoid windows. Go to the lowest floor; into a small, windowless chamber like a bathroom or closet; under a stairwell; or into an interior hallway with no windows. Crouch as low as possible to the floor, facing down, and cover your head with your hands. A bathtub may offer partial protection. Even in an interior room, you should cover yourself with some sort of thick padding, like a mattress or blankets, to protect yourself against falling debris in case the roof or ceiling fails. Do not waste time opening windows—it won’t protect your home from damage
and if a tornado hits your building it’s likely to blow out the windows anyway.
In an office building, a hospital, a nursing home, or a skyscraper: Go directly to an enclosed, windowless area in the center of the building. Crouch down and cover your head. Interior stairwells are usually good places to take shelter. If the stairs are not crowded, move quickly to a lower level. Stay out of the elevators; you could be trapped in them if the power is lost.
In a mobile home: Get out! Even if your home is tied down, you are probably safer outside, even if the only alternative is to seek shelter out in the open. Most tornadoes can destroy even tied-down mobile homes, and it is best not to play the low odds that yours will make it. If your community has a tornado shelter, go there fast. If there is a sturdy permanent building within easy running distance, seek shelter there. Otherwise, lie flat on low ground away from your home, protecting your head. If possible, use open ground away from trees and cars, which can be blown onto you.
