Thunderstorms, Hurricanes and Tornadoes. Thunderstorm Facts. Right now there are about 2,000 thunderstorms occurring worldwide There are about 45,000 thunderstorms per day!! U.S. gets 100,000 per year!. Severe Thunderstorms. Torrential Downpours Strong winds at greater than 58 mph
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Thunderstorm Facts • Right now there are about 2,000 thunderstorms occurring worldwide • There are about 45,000 thunderstorms per day!! • U.S. gets 100,000 per year!
Severe Thunderstorms • Torrential Downpours • Strong winds at greater than 58 mph • Hail ¾ inch diameter (or larger) • Frequent lightning
Severe Thunderstorm Watch • Issued by National Weather Service • This means that conditions are favorable for a thunderstorm • Length is multiple hours.
Severe Thunderstorm Warning • Issued By Local Weather Service • Means a severe storm has been spotted by doppler radar • Usually only an hour
Types of Lightning • Cloud-to-ground (CG) • Intra-cloud (IC) • Ribbon lightning • Sheet lightning • Heat lightning • Ball lightning
Lightning Safety • Stay indoors, away from doors and windows. • Do not take baths or showers. • Do not use phones with cords.
How Far Away Was That Lightning? • When you see the flash, start counting seconds. • When you hear the thunder, stop counting. • Every 5 seconds is equal to 1 mile.
F-Scale • F0 – Light damage • F1 – Moderate damage • F2 – Considerable damage • F3 – Severe damage • F4 – Devastating damage • F5 – Incredible damage (Auntie Em!)
Tornado Watch • Conditions are favorable for a tornado to form
Tornado Warning • A tornado has formed.
Tornado Safety • Get indoors and stay there • Stay away from doors and windows • Get to lowest level possible • Don’t get near things that can fall on you
When to expect • Hurricane season is June through November • Peak is in September
Formation of Hurricanes • Tropical Depression • Tropical Storm • Hurricane
Tropical Depression • Cluster of organized thunderstorms • Not very compact • Sustained winds of at least 30 mph • Given a number
Tropical Storm • Winds above 39 mph • Given a name • More organized • If hits land, most damage caused is by rainfall.
Hurricane • Winds over 74 mph • Well defined center of circulation • Eye Wall • Damage from includes: • Wind • Storm surge • Rain
Pressure in hurricane • A way to tell strength of hurricane is by its pressure • Measured in millibars (mb) • Higher pressures are weak, lower are stronger
Naming System • A list of names from A-W (excluding Q) • Alternate from male to female • 6 lists, repeated in cycle • Big name storms replaced
Saffir-Simpson Scale • Designed by Herbert Saffir and Bob Simpson • Divides hurricanes into categories based on maximum sustained winds.
Category 1 • Winds- 74-95 mph • Storm Surge- 4-5 ft. • Pressure- 986mb • Damage- mobile homes, trees, minor costal flooding
Category 2 • Winds- 96-110 mph • Storm surge- 6-8 ft. • Pressure- 965- 979 mb • Damage- Some roof and window. Damage to piers on coast. Small crafts. vegetation
Category 3 • Winds- 111-130 mph • Storm surge- 9-12 ft. • Pressure- 945-964 mb • Damage- structure damage to homes and buildings. Mobile homes destroying. Major coastal flooding with a potential for inland flooding.