Tornadoes Be able to define what a tornado is.

Be able to list several facts about tornadoes.

1. Where do tornadoes most

occur in the world? • U.S. is # 1

• Tornadoes are most common in “Tornado Alley.”

Tornado Facts • 2. 1000 tornadoes spin up beneath

T-Storms each year in the U.S. – 1,253 tornadoes per year in the U.S.

• 3. Typically kill about 60 – 80 people

• 4. Tornadoes are violently rotating

columns of air attached to a

thunderstorm and in contact with the

ground, whether or not a

condensation funnel is visible to the

ground.

– Stronger pressure gradient than a

hurricane.

2013 Tornado Data

5. Where have tornadoes occurred?

• Tornadoes have occurred:

– In all 50 States

– On all continents except Antarctica

6a. When do most tornadoes occur?

• April to July

• During late spring to early summer.

6b. When do most tornadoes occur?

• 2 pm to 8 pm

• During afternoon and evening hours

7. What forward speed do tornadoes

move at?

• The average forward speed is 30mph but may vary from nearly stationary to 70mph

8. Where does a tornado come from?

• It’s called a funnel cloud until it makes contact with the ground.

• A cloud that protrudes below the cloud base is called the wall cloud. – Updraft of the storm

9. How do Tornadoes look? • Tornadoes take different forms, some are large and

ominous, while others are relatively small and may be difficult to see.

Tornado Variations in Appearance

• Pencil-shaped tornado about the time of F5

damage near Union City, OK, May 24,1973.

Tornado Variations in Appearance

• Cone-shaped tornado with debris fan south of

Hill City, KS, looking west, June 9, 2005.

Tornado Variations in Appearance

• “Wedge” tornado, where the visible funnel is wider than

the distance from ground to surrounding cloud base,

looking northwest near Argonia, KS, May 29, 2004.

10. What is a Waterspout • Waterspouts are tornadoes that occur over water.

– Two types of water spouts

• Type A waterspout forms in thunderstorm and travels over water (More

violent)

• Type B waterspout forms from building cumulus clouds (less violent)

– If this forms on land it is called a landspout

1950 – 2006 Tornado Tracks

http://www.srh.noaa.gov/images/fxc/bmx/graphicast/image_full4.gif

11. Tornadoes usually move in which direction?

• Tornadoes can appear from

any direction. Most move

from southwest to

northeast.

• Most tornadoes -- but not

all! -- rotate cyclonically, (which is counterclockwise in the N.H.)

12. What scale is used to measure tornado strength?

Fujita Scale – Because tornado winds cannot be measured directly,

a rating on the Fujita scale is determined by assessing the worst damage produced by the storm.

Fujita Scale

• F0 (40-72 mph) – Light damage. Some damage to chimneys; branches broken off trees; shallow-rooted trees

pushed over; sign boards damaged.

• F1 (73-112 mph) – Moderate damage. The lower limit is the beginning of hurricane wind speed; surface peeled

off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off the roads.

• F2 (113-157 mph) – Considerable damage. Roofs torn off frame houses; mobile homes demolished; boxcars

pushed over; large trees snapped or uprooted; light-object missiles generated.

• F3 (158-206 mph) – Severe damage. Roofs and some walls torn off well-constructed houses; trains overturned;

most trees in forest uprooted; heavy cars lifted off ground and thrown.

• F4 (207-260 mph) – Devastating damage. Well-constructed houses leveled; structures with weak foundations

blown some distance; cars thrown and large missiles generated.

• F5 (261-318 mph) – Incredible damage. Strong frame houses lifted off foundations and carried considerable

distances; automobile sized missiles thrown through the air in excess of 100 yd (equivalent to 91 m); trees debarked.

13. How do Tornadoes Form?

Need Wind Shear

• A change in wind direction

and an increase in wind

speed with increasing height

– creates an invisible, horizontal

spinning effect in the lower

atmosphere.

– Rising air within the

thunderstorm's updraft tilts the

rotating air from horizontal to

vertical.

Tornado Formation

Weak Tornadoes F0-F1

• 69% of all tornadoes

• Less than 5% of

tornado deaths

• Lifetime 1-10+

minutes

• Winds less than 110

mph

Strong Tornadoes F2-F3

• 29% of all tornadoes

• Nearly 30% of all

tornado deaths

• May last 20 minutes or

longer

• Winds 110-205 mph

Violent Tornadoes F4-F5

• Only 2% of all

tornadoes

• 70% of all tornado

deaths

• Lifetime can exceed 1

hour

• Winds greater than 205

mph

Environmental Clues

• Tornadoes are often preceded by a dark, often greenish sky, large hail, and often a loud roar, similar to a freight train.

• Most strong and violent tornadoes occur with "supercell" thunderstorms.

Remember Other Threats

• In addition to tornadoes, thunderstorms often produce other hazards.

• Flash Floods/Floods – The number ONE thunderstorm-related killer -- averages 146

deaths annually.

• Lightning – Kills 75 to 100 people each year

• Damaging Straight-Line Winds – Can reach speeds of 140 mph

• Large Hail – Often the size of golf balls and occasionally can reach grapefruit

size. Hail causes several hundred million dollars in damage annually to property and crops.

Tornado Watch

• Tornado Watch

– alert people to the possibility of tornadoes in a

specified area for a particular time.

Tornado Warning • Tornado Warning

– A tornado warning is issued when a tornado has actually been sighted in an area or is indicated by weather radar.

– With new technology we have gone from 5 minutes to 15 minutes of warning time for tornadoes

Radar Tornadoes (J-Hook)

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=Da0iuaA5uJY2uM&tbnid=AmZ1uyTEj3jdYM:&ved=0CAUQjRw&url=http%3A%2F%2Fwww.connectmidmissouri.com%2Fweather%2Fstory.aspx%3Fid%3D454988&ei=E0eeUpbxGonHqgGHo4AQ&bvm=bv.57155469,d.aWc&psig=AFQjCNG9zeJJklzB0uhS6mXnkYmFxk7asA&ust=1386190869841400

Tornado Safety

• If you are caught outdoors, seek shelter in a

basement, shelter or sturdy building.

• If you cannot quickly get to a shelter,

immediately get into a vehicle, buckle your seat

belt and try to drive to the closest sturdy shelter.

• If flying debris occurs while you are driving, pull

over and park. You have the following options as

a last resort:

Tornado Safety

• Stay in the car with the seat belt on. Put

your head down below the windows,

covering with your hands or a blanket if

possible.

• If you can safely get noticeably lower than

the level of the roadway, exit your car, and

lie in that area, covering your head with your

hands.

Tornado Safety

• Flying and falling debris is the biggest hazard in

a tornado. To be safe, you should get inside, get

down and cover up. Underground or in a Safe

Room is your first choice. If no underground

shelter is available, get to the center of a sturdy

building on the lowest level. Put as many walls

between you and the tornado as possible. Stay

away from windows and doors. Cover up to help

minimize being injured by flying or falling debris.