Tornadoes 11/16/15

Tornado Facts Winds can exceed 300 mph!!! Around 1,000 occur on average each year in the U.S. Kill 80, injure 1,500 people each year on average Can have a path up to a mile wide!!! Can occur any time of the year, but peak during the spring (March-June) Occur most frequently in the central U.S. in a region nicknamed “Tornado Alley”

What are tornadoes? A tornado is a violently rotating column of air extending from a thunderstorm to the ground.

Ingredients for a tornado Change in wind direction Increase in wind speed Increasing height Rising air within a thunderstorm

We have a pretty good idea… How do they form? We have a pretty good idea…

How do they form? Most tornadoes form from thunderstorms. You need warm, moist air from the Gulf of Mexico and cool, dry air from Canada. When these two air masses meet, they create instability in the atmosphere.

Step 1 Before a t-storm, a change in wind direction and an increase in speed forms an invisible, horizontal spinning effect in the lower atmosphere (at the base of the storm)

Step 2 Rising air within the t-storm (updrafts) tilts the rotating air from horizontal to vertical

Step 3 Vertical rotation now extends 2-6 miles up into the t-storm. Now a tornado may form and extend from this area of rotation to the ground.

A Tornado Develops

Tornado damage is measured by the Fujita scale Not Fajita! Dr. T. Theodore Fujita came up with a scale which measures the strength of tornadoes

The Damage done is connected to the strength/wind speed of the tornado SCALE WIND SPEED POSSIBLE DAMAGE F0 40-72 mph Light damage: Branches broken off trees; minor roof damage F1 73-112 mph Moderate damage: Trees snapped; mobile home pushed off foundations; roofs damaged F2 113-157 mph Considerable damage: Mobile homes demolished; trees uprooted; strong built homes unroofed F3 158-206 mph Severe damage: Trains overturned; cars lifted off the ground; strong built homes have outside walls blown away F4 207-260 mph Devastating damage: Houses leveled leaving piles of debris; cars thrown 300 yards or more in the air F5 261-318 mph Incredible damage: Strongly built homes completely blown away; automobile-sized missiles generated

Fujita Tornado Intensity Scale F0: Gale tornado (40-72 mph); light damage. Some damage to chimneys; break branches off trees; push over shallow-rooted trees; damage to sign boards.

                                                         F1: Moderate tornado (73-112 mph); moderate damage. The lower limit is the beginning of hurricane wind speed; peel surface off roofs; mobile homes pushed off foundations or overturned; moving autos pushed off the roads.

                                                         F2: Significant tornado (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: Severe tornado (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: Devastating tornado (207-260 mph); Devastating damage. Well- constructed houses leveled; structure with weak foundation blown off some distance; cars thrown and large missiles generated.

                                                         F5: Incredible tornado (261-318 mph); Incredible damage. Strong frame houses lifted off foundations and carried considerable distance to disintegrate; automobile sized missiles fly through the air in excess of 100 yards; trees debarked; incredible phenomena will occur.

Tornadoes are found most frequently in the U.S. In the United States, the area where the tornadoes hit the most is called Tornado Alley. The states which are in the tornado alley are: Arkansas, Iowa, Kansas, Louisiana, Minnesota, Nebraska, North Dakota, Ohio, Oklahoma, South Dakota, and Texas.

Number of Tornadoes in Specific Years Tornadoes have been increasing throughout the years…gradually, but they have increased. Take a look at the number of tornadoes in 2004 compared to the number of tornadoes in 1979.

Biggest, Costliest Outbreaks The April 3-4, 1974 Super Outbreak was the largest known outbreak, with 148 tornadoes in 11 states, killing 315 people, injuring more than 5,300 and causing $600 million in damages. Alabama, Kentucky and Ohio were the states hardest hit. Perhaps the most notable tornado of the outbreak was one which touched down southwest of Xenia, Ohio. The violent tornado destroyed half the town, killing 34 and causing property damages of more than $100 million.

                                                                                                                        

Types of Tornadoes

What is a waterspout? A waterspout is just a weak tornado that forms over water. They are most common along the Gulf Coast. Waterspouts can sometimes move inland, becoming tornadoes causing damage and injuries.

A gustnado in southeastern Wisconsin on 4 October 2002. What is a gustnado? A gustnado is a short-lived, relatively weak whirlwind that forms along a gust front. A gust front is the surge of very gusty winds at the leading edge of a thunderstorm's outflow of air. Gustnadoes are not tornadoes. They do not connect with any cloud-base rotation. But because gustnadoes often have a spinning dust cloud at ground level, they are sometimes wrongly reported as tornadoes. Gustnadoes can do minor damage. A gustnado in southeastern Wisconsin on 4 October 2002.

                                                                                 

Tornado watch and warning TORNADO WATCH - Tornadoes are possible in your area. Stay tuned to the radio or television news. TORNADO WARNING - A tornado is either on the ground or has been detected by Doppler radar. Seek shelter immediately! Red: Tornado Warning Purple: Flash Flood Warning

Where is the safest place to go during a tornado? Tornadoes Where is the safest place to go during a tornado? You might ask yourself where the safest place to be during a tornado is. Well, depending where you are and what resources you have, tells you what your safest place is. If you have a basement, that is the safest place to be. If not, a shower, the center of the room, or an inner hallway. If you are outside, the best place to find is the lowest area like a ditch.

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