Monday 3/2/2015 Agenda: Severe Weather Tornadoes, Hurricanes and Flash Floods  Notes: Tornadoes, Hurricanes and Flash Floods  Activity: Graphic Organizer  WEATHER AND CLIMATE QUEST WEDNESDAY/THURSDAY! Homework/Classwork Severe Weather Graphic Organizer due Tuesday 3/3/2015 for 25 Points

How Does Severe Weather Happen? Tornadoes – –Definition: A violently rotating column of air, usually forming from a cumulonimbus cloud, with circulation reaching the ground. It nearly always starts as a funnel cloud and may be accompanied by a loud roaring noise. How do TORNADOES happen? –Form from thunderstorms. –Caused by convection of warm and cold air –These updrafts alter the air's rotation from horizontal to vertical, creating conditions in which a funnel can develop. –If conditions are right and the funnel forms, it can extend to the ground, forming a tornado.

AZ Tornado – 8/2006 (by CO River north of Yuma)

There have been 211 TORNADOS reported in AZ between 01/01/1950 and 12/31/2006. The latest one occurred on October 14, 2006, 11 miles south of Bellemont (near Flagstaff) A severe thunderstorm produced a tornado that tracked about 9 miles along the Western Mogollon Rim. A storm survey revealed extensive tree damage along the 9 mile path. Very large trees were snapped off at ground level and deposited some distance with no drag marks. This tornado was generally F0. A small section of the damage path exhibited upper-end F1 to lower-end F2 damage. TORNADOS in Arizona!!!

How Does Severe Weather Happen? Flash Flood – –Definition: A rapid and extreme flow of high water into a normally dry area or above a predetermined flood level after intense rainfall, dam failure, ice jam. How do FLASH FLOODS happen? –The result of too much rain falling in too small an area, in too short a time. –Occur in seconds and minutes. –Usually occur at night and when there is an abundance of atmospheric moisture. –Flash-flood waves can roll boulders, tear out trees, destroy buildings and bridges, and scour out new channels. –Walls of water can reach 10–20 ft.

AZ Flash Flood – 9/2006 (between Fountain Hills & Rio Verde)

January 8-19, 1993 The framing for the new Mill Avenue Bridge was washed away by the raging Salt River (Tempe Town Lake area). A large landfill in Mesa was washed away. Phoenix alone sustained at least $4.2 million in damages from this prolonged period of heavy rains. Early estimates of damage were at least $56 million statewide. AZ experienced its worst flooding in 10 years as record rainfall and associated flooding forced many from homes and disrupted business. The Red Cross reported 678 dwellings destroyed or damaged. A Presidential Federal Disaster Declaration was signed by the President on January 19th. Flash Flood

How Does Severe Weather Happen? Hurricanes – –Definition: A tropical cyclone in the Atlantic, Caribbean Sea, Gulf of Mexico, or eastern Pacific, wind speeds of 74 mph or greater. How do HURRICANES form? –Occur due to convection of warm and cold air, and convection of warm and cold water –These conditions may lead to thunderstorms. –If winds pick up to 40 miles per hour, the tropical disturbance officially becomes a tropical storm.

Well…almost….it was a Tropical Storm (not yet a hurricane, Category 1) that hit Yuma County (Lower Colorado River Valley) on September 25, An estimated $ million in damage was sustained by crops throughout Yuma County due mainly to flooded crops. About $30-40 million was to lemon trees. The heavy rain was attributed to Tropical Storm Nora, that formed off the Pacific coast of Mexico, and aided by waters warmed by El Niño, eventually peaked at Category 4 intensity. There were no reported fatalities or injuries in AZ. What?! A Hurricane in AZ?!

(north of Puerto Rico) This infrared image detects varying levels of moisture in the upper tropospher e. GRAY – DEEP BLUE = more moisture BLACK – DEEP RED = drying. With this image of Bertha, tremendous amounts of moisture are being pumped high into the atmosphere near the center of the hurricane. The BRIGHT BLUE DOT is the eye, which contains much less moisture than the surrounding CDO (Central Dense Overcast).