Conditions Required for Formation Low pressure system Low pressure system Warm Water; 80 F Warm Water; 80 F Begin off the W. coast of Africa Begin off the W. coast of Africa The Stages of a Hurricane (based on changes in wind speed) 1. Tropical Depression (L pressure system) 2. Tropical Storm- gets a name (winds mph) 3. Hurricane (winds over 74 mph) Why do Hurricanes travel from east to west? None at the Equator! The Saffir-Simpson Scale: based on wind speed Other names: Typhoons in the western PacificTyphoons in the western Pacific Cyclones in Australia/Indian oceanCyclones in Australia/Indian ocean Hurricanes in the AtlanticHurricanes in the Atlantic 2015- year of the Pacific hurricane/typhoon Hurricane Patricia- strongest hurricane ever! Timeline of 2015 hurricanes When is Hurricane season? Fall ( peaks in Aug.- Sept.) Fall ( peaks in Aug.- Sept.) Why? Why? 2015 Atlantic hurricane season Joaquin; Bahamas Bahamas Sunk El Faro Sunk El Faro TS Erika Killed 36 people in DR Killed 36 people in DR flooding flooding Parts of a hurricane eye miles wide eye miles wide light winds Air sinking clear/broken clouds eye wall eye wall very strong winds ring of intense thunderstorms Parts of a hurricane (cont.) Spiral Rain bands- heavy rain; wind Spiral Rain bands- heavy rain; wind Cross section of a hurricane Cross section of a hurricane Eye Wall Do Hurricanes affect Detroit? Just rain Just rain Hurricane Damage! Hurricane Damage due to wind and water due to wind and water rains can cause flooding and mud slides rains can cause flooding and mud slides Most deaths are due to the storm surge Most deaths are due to the storm surge Gulf Shores, AL (after Hurricane Ivan 2004) Power of Wind Andrew 1992 Ivan 2004 Iris 1991 STORM SURGE OCEAN WATER SUCKED UPWARD Katrinas storm surge Factors Affecting Storm Surge shape of the coastline shape of the coastline the magnitude of the hurricane the magnitude of the hurricane What to do if a hurricane warning is issued? LEAVE THE AREA Hurricane forecasting 3 major hurricanes were predicted for 2014; 7 are predicted for 2015 Satellites are most useful in detecting where hurricanes are Satellites are most useful in detecting where hurricanes are To predict direction they will go To predict direction they will go Fronts Water temp. Wind directions Still fickle! Hurricane Dissolving storm passes over cooler waters OR storm passes over cooler waters OR storm makes landfall storm makes landfall Once the warm water is gone so is the hurricane! What Determines What is the Worst Hurricane? Winds ?? Deaths ?? Cost ?? Most Powerful Atlantic Hurricanes Deadliest Atlantic Hurricanes Galveston 1900-deadliest natural disaster in U.S. history Costliest Atlantic Hurricanes Katrina- $80 billion Sandy- $65 billion Andrew 1992 Cost of hurricane damage is increasing because. More people are moving to hurricane prone areas! More people are moving to hurricane prone areas! Hurricane Katrina 2005 Levees broke Added to flooding Added to flooding New O. below sea level! New O. below sea level! 1833 died 1833 died Gulfport, Mississippi Wind side of storm Wind side of storm Superstorm Sandy Sandy- 285 died Super storm sandy Unusual conditions Unusual conditions Bermuda H was absent Steered Sandy left Gulf stream 3 warmer than normal Combined with cold front from main land High spring tide Jet stream moved farther south- added power to storm