tornadoes. tornado formation severe “super cell” thunderstorm (1% spawn tornadoes) often occur...
TRANSCRIPT
Tornadoes
Tornado Formation• Severe “Super Cell” Thunderstorm (1% spawn
tornadoes)• Often occur along cold fronts and move to NE• Strong updrafts• Wind shear (change in direction or strength of
winds from top to bottom of storm)
Funnel Cloud v. Tornado
Tornado Funnel Cloud
Waterspout- over water - less power- smaller tempgradient
World Tornado Geography
• USA: 90%+ of all tornadoes
USA Tornado Geography
• Every state!• Tornado Alley (TX, OK, KS, NE)
USA Tornado Season
Most common when temperature gradient in central U.S. is greatest.
USA Tornado Occurrence
• About 800-1000 tornadoes spotted each year.
Tornado Classification• Fujita F-scale
– F0 (winds < 120 mph) to F5 (winds 200-300+ mph)– based on rotational wind speed and damage done
• Size: Tornadoes generally < 1/4 mile wide (damage path only 150 ft.)
Deadliest Tornado• Tri-state tornado outbreak of March 18, 1925
• Kills 689 people in Missouri, Illinois & Indiana
Largest Tornado Outbreak
• April 3-4, 1974 Super-Outbreak
• 148 tornadoes overnight across 11 states
Tornado Forecasting• NEXRAD doppler radar (WSR-88D)
– 138 stations across the USA• Intensity of storm noted by amount of reflection off rain,
hail, and ice crystals.• Hook cloud is an indicator.
Orlando, Florida
Tornado Indicators• What to look for….