Severe Weather: Thunderstorms, Tornadoes, and Hurricanes, oh my!

Thunderstorms Thunderstorms are small, intense weather systems that produce strong winds, heavy rain, lightning, and thunder. Thunderstorms form from warm moist air and along cold fronts.

Recipe for a Thunderstorm There are three ingredients needed- The air near the earth’s surface must be warm and moist. It rises or moves upward, which is called an updraft. The atmosphere must be unstable, meaning the surrounding air is colder than the rising air mass. As the warm air mass rises, it cools and turns into water vapor, condenses and forms CUMULONIMBUS Clouds.

As the cloud continues to build, ice particles form near the top of the cloud. As they get large-they form hail. As the hail falls, cold air moves down with it, causing a downdraft. https://www.brainpop.com/science/weather/thunderstorms/

Grab Toto!! TORNADOES Are a low pressure storm that usually forms over land in an average year, 800 tornadoes are reported in the U.S. a tornado is defined as a violently rotating column of air extending from a thunderstorm to the ground… the rotating column of air is called the vortex the vortex is only visible when debris and dirt gets carried up with the winds

Where do they come from? Tornadoes come from the energy released in a thunderstorm. What makes them dangerous (as compared to hurricanes) is that their energy is concentrated in a small area, only a hundred yards across

When & Where do they occur? Most common east of the Rocky Mountains and west of the Appalachian Mountains. They occur mostly during the spring and summer (April-June) They usually occur during the late afternoon and early evening. Usually happen along cold fronts

How long is a tornado usually on the ground? Can range from a few seconds to several hours ... 5 minutes is average How fast do tornadoes move? Movement can range from virtually stationary to more than 60 miles per hour ... Average is 10-20 miles per hour.

Watch—means conditions are favorable for tornado to develop Warning—means that tornado has been spotted

MEASURING DESTRUCTION The Enhanced Fujita Scale rates tornadoes based on the amount and type of wind damage produced.

EF-0. Light damage Wind 65 to 85 mph. Causes some damage to siding and shingles

EF-1. Moderate damage Wind 86 to 110 mph. Considerable roof damage EF-1. Moderate damage Wind 86 to 110 mph. Considerable roof damage. Winds can uproot trees and overturn single-wide mobile homes. Flagpoles bend.

EF-2. Considerable damage Wind 111 to 135 mph EF-2. Considerable damage Wind 111 to 135 mph. Most single-wide mobile homes destroyed. Permanent homes can shift off foundation. Flagpoles collapse. Softwood trees debarked.

EF-3. Severe damage Wind 136 to 165 mph. Hardwood trees debarked EF-3. Severe damage Wind 136 to 165 mph. Hardwood trees debarked. All but small portions of houses destroyed.

EF-4. Devastating damage Wind 166 to 200 mph EF-4. Devastating damage Wind 166 to 200 mph. Complete destruction of well-built residences and large sections of school buildings

EF-5. Incredible damage. Wind +200 mph. Significant structural deformation of mid- and high rise buildings. Strong frame houses leveled off foundations and swept away; automobile-sized missiles fly through the air in excess of 100 yards

Location: El Reno, Oklahoma Deaths: 20, including 4 storm chasers Injuries: 115 Widest tornado ever observed or surveyed – 2.6 miles wide Intensity – EJ5 Wind Speeds – 296 mph https://youtu.be/mPYVzhSEgAI

HURRICANES Low pressure systems that form over warm, tropical waters near the equator Most form between 5 and 20 degrees north latitude — they almost never form in the South Atlantic

Different names are given to hurricanes depending on where they form Atlantic—we call them hurricanes Pacific—they are called typhoons 3. Indian Ocean—they are called cyclones

Mature hurricanes average about 350 miles across They have the lowest barometric pressures ever recorded with any storm (905 millibars is lowest recorded) These huge air pressure differences is what creates the rapid, inward spiraling of winds

HURRICANE DEVELOPMENT When winds have developed speeds from 39 to 73 miles per hour, it is called a tropical storm (storms are given names when they begin to have winds of this speed). 2005 Katrina Developing

The storm becomes a hurricane when it reaches a wind speed of over 74 mph Hurricane Formation

When a season is very active, Greek letters are used to name tropical storms after the letters of the alphabet had been used.

THE END OF A HURRICANE When a hurricane travels over land or cold water, its energy source (warm water) is gone and the storm weakens, quickly dying.

HURRICANE SEASON Occurs from June through November Most hurricanes form during the late summer months because the ocean is still retaining heat from the warmer earlier months

CATEGORY WIND SPEED STORM SURGE DAMAGE MEASURING DESTRUCTION We use the Saffir-Simpson scale to rank hurricane intensities Saffir-Simpson Scale CATEGORY WIND SPEED STORM SURGE DAMAGE 1 74-95 mph 4-5 feet Minimal 2 96-110 mph 6-8 feet Moderate 3 111-130 mph 9-12 feet Extensive 4 131-155 mph 13-18 Extreme 5 Greater than 155 Greater than 18 Catastrophic Video Clip on Wind Tunnel

STORM SURGE and FLOODING account for 88% of hurricane-related deaths https://weather.com/safety/hurricane/news/hurricanes-tropical-storms-us-deaths-surge-flooding

Category 5 Facts There have been 33 Category 5 hurricanes on record in the Atlantic since 1924. Most Category 5 Atlantic hurricanes have occurred in August and September. Three Atlantic hurricanes have made landfall in the continental U.S. as a Category 5 https://weather.com/storms/hurricane/news/atlantic-hurricane-category-five-history-0