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Just-in-Time Lecture Hurricane

This JIT lecture provides the best information about the science behind hurricanes and how it helps prepare for primary and secondary prevention. Learn about hurricane formation, anatomy, and the potential impacts.

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Just-in-Time Lecture Hurricane

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  1. www.pitt.edu/~super/ Just-in-Time Lecture Hurricane Ali Ardalan, Ronald E. LaPorte, Eugene Shubnikov, Faina Linkov, Mehdi Russel & Eric K. Noji

  2. What is the Disaster Supercourse? http://www.pitt.edu/~super1

  3. Mission Statement: The Global Health Network Disaster, Network for Hurricane is designed to translate the best possible scholarly information from leading researchers to educators worldwide.

  4. What is a JIT lecture? http://www.pitt.edu/~super1

  5. Lecture objectives: • To provide the best possible information about the science of Hurricane • To learn how the science can help prepare us for primary & secondary prevention consequences of Hurricane

  6. Origin of the word “Hurricane” Carib god ‘’Hurican’’ was derived from Mayan god 'Hurakan', one of their creator gods, who blew his breath across Chaotic water & brought forth dry land & later destroyed men of wood with a great storm and flood . HURRICANE derived from ‘’Hurican’’, the Carib god of evil !! Glossary of Meteorology

  7. Hurricane at a glance! • A tropical storm with 74 mph speed winds Hurricane winds blow in a large spiral around a relative calm center known as the “Eye." • The “Eye" is generally 20 to 30 miles wide & the storm may extend outward 400 miles.

  8. Hurricane at a glance! • A single hurricane can last for > 2 weeks over open waters • Peak months: August & September • Hurricane season: 1st June-30th November

  9. Basic terminology in hurricanes: • Sustained wind: • Long lasting wind, reporting based on: • 1 min average time in Atlantic & NE Pacific • 10 min average time in rest of the world • Maximum sustained wind: • The highest 1 min “Surface winds” within system circulation

  10. Basic terminology in hurricanes: • Gusts • 3-5 seconds wind peak • 20-25% > 1 min sustained wind

  11. Basic terminology in hurricanes: • Storm surge: • Onshore rush of sea or lake water caused by the high winds associated with a land falling cyclone and secondarily by low pressure of the storm Be careful: Storm surge & Storm tide are different !

  12. Hurricane Anatomy • EYE: • Centre of a hurricane characterized by a roughly circular area of light winds & rain-free skies & lowest pressure • Developed when the maximum sustained wind speeds exceed 78 mph • Ranged size: 5-60 miles (20 miles in average) • Shrinking the eye, intensifying the storm

  13. Hurricane Anatomy • EYE WALL: • Organized band of convection surrounding eye or the centre • Contains cumulonimbus clouds, severest thunderstorms, heaviest precipitation and strongest winds

  14. Hurricane Anatomy • Spiral rain bands: • Large bands of clouds & precipitation spiral from the eye wall

  15. Hurricane Anatomy Moat: • Region between the eyewall & an outer rainband, such as a secondary eyewall & rainband • Relatively light rain region between rainband & eyewall

  16. Environmental Condition for tropical cyclone formation • Warm ocean waters of at least 26.5 C (80 F) • Warm, humid air • Relatively moist layers near mid-troposphere (5 km) • Minimum distance of at least 500 km from equator

  17. Environmental Condition for tropical cyclone formation • Pre-existing near-surface disturbance with sufficient vorticity & convergence • Low values (less than 23 mph) of vertical wind shear between the surface & the upper troposphere

  18. Sequence of Hurricane formation: Tropical Disturbance 1 Tropical Depression 2 Tropical Storm 3 Hurricane 4 4 3 2 1

  19. Hurricane term: • REGIONALLY specific names for a strong • “Tropical cyclone" Tropical cyclones with max. sustained winds of less than 39 mph with close circulation • Tropical Depression • Tropical Storm Tropical cyclones with max. sustained winds of 39-73 mph • Hurricane • Typhoon • Severe tropical • cyclone • Tropical cyclone Tropical cyclones with sustained winds of 74 mph

  20. REGIONALLY names of “Tropical cyclones” with winds of 74 mph • Hurricane • N Atlantic Ocean, NE Pacific Ocean E of dateline, or S Pacific Ocean E of 160E • Typhoon • NW Pacific Ocean W of dateline

  21. REGIONALLY names of “Tropical cyclones” with winds of 74 mph • Severe tropical cyclone • SW Pacific Ocean W of 160E or SE Indian Ocean E of 90E • Severe cyclonic storm • The North Indian Ocean • Tropical cyclone • The Southwest

  22. More details about Hurricane formation (1) Wind blows the clouds clockwise & start pulling up ocean water. Then the bottom water moves counterclockwise. Air sinks into the centre (the eye).

  23. More details about Hurricane formation (2) Wind spins around the eye, where hurricane is the strongest. As the wind flows higher it becomes weaker and flows clockwise.

  24. Hurricane death • A mature hurricane is a well-oiled meteorological machine, but disruption of the processes that drive storm (interaction with land or colder air feeding in) will begin to destroy storm, & the disintegration of a hurricane is quick & dramatic. • Important death factors: • Westerly winds • Going over land as there is warm water

  25. Cape Verde-type hurricanes • Atlantic basin tropical cyclones fairly close (<1000 km) of Cape Verde Islands & then become hurricanes before reaching Caribbean • Typical months: August &September • Frequency: Ranged 0-5, with an average of 2

  26. Hurricane/Tropical Cyclone • Intensity Scales: • Atlantic hurricanes ranking (Saffir-Simpson hurricane intensity scale) • Australian tropical cyclones ranking

  27. Saffir-Simpson hurricane intensity scale

  28. Australian tropical cyclones ranking

  29. Factors contributing in hurricane damages: • Distance from zone of maximum winds • How exposed the location is • Building standards • Vegetation type • Resultant flooding

  30. Major hurricane = Intense hurricane • Max. sustained surface winds: At least 111 mph • Category 3,4 and 5 on Saffir-Simpson scale • Cause > 83% of damages in the USA even though account for only 21% of tropical cyclone landfalls

  31. HURRICANE WARNING: • Added to a hurricane advisory that sustained winds of ≥74 mph associated with a hurricane are expected in a specified coastal area within ≤24 h. • Can remain in effect when dangerously high water or a combination of dangerously high water & exceptionally high waves continue, even though winds may be less than hurricane force. • Is used to inform the public and marine interests of the storm's location, intensity, and movement.

  32. HURRICANE WATCH • An announcement added to a hurricane advisory that hurricane conditions pose a possible threat to a specified coastal area within 36 hours. • Is used to inform the public and marine interests of the storm's location, intensity, & movement.

  33. Subtropical cyclone: • Low-pressure system in tropical or subtropical latitudes cyclones • Radius of max. winds farther out (on order of 60-125 miles from the centre) than what is observed for purely tropical systems • Max. sustained winds no stronger than 74 mph • Classified by max. sustained surface winds: • < 37 mph : Subtropical depression • ≥ 38 mph : Subtropical storm Transform to tropical cyclones in many times & then Hurricane,like Hurricane Florence, Nov 1994 !

  34. USGS Slide: Dr. Tom Songer

  35. Hurricane direct related health hazard High winds Storm surge Flooding Tornados

  36. Hurricane direct related health hazard: High Winds Energy of winds = wind velocity squared (E = V2) 2 times wind speed = 4 times destructive energy

  37. Hurricane direct related health hazard: High Winds • Intensity of a landfalling hurricane is expressed in terms of categories that relate wind speeds & potential damage (Saffir-Simpson Scale) • Category 4 hurricane (131-155 mph winds) causes 100 times damage of Category 1 storm!

  38. Hurricane direct related health hazard: Rainfall & Flooding • Responsible for 59% of the deaths associated with tropical cyclones in the US • Intense rainfall is not directly related to wind speed. Some of the greatest rainfall amounts occur from weaker storms that drift slowly or stall over an area.

  39. Hurricane direct related health hazard: Rainfall & Flooding: NHC Preventive recommendations • When you hear hurricane, think inland flooding • Determine whether you live in a potential flood zone • If advised to evacuate, do so immediately • Keep abreast of road conditions through the news media • Move to a safe area before access is cut off by flood water • Do not attempt to cross flowing water. As little as 6 inches of water may cause you to lose control of your vehicle • Develop a flood emergency action plan • Have flood insurance

  40. Hurricane direct related health hazard: Storm Surge • 50 - 100 miles wide • 4 - 6 feet for a minimal hurricane to > 20 feet for the stronger ones

  41. Hurricane direct related health hazard: Tornado • More intense hurricane, greater tornado threat • 10% of hurricane related death in the US • Mostly within 24 hours after hurricane landfall • Mostly within 150 miles of the coastline

  42. Hurricane direct related health hazard: Tornado • Occurrence during morning & afternoon rather than evening or night due to need for heat source • The Gulf of Mexico hurricanes produce more tornadoes than Atlantic storms • Mostly occur within 30 miles of center of cyclone • Can reach up to 300 mph at a forward speed of 60 mph and are usually 100-300 yards wide

  43. Hurricane: History of death & economical damages 1990-2003

  44. Hurricane Preparedness, Before Hurricane Season Stars (8 points): • 1) Plan an evacuation route • Contact the local emergency management office or Red Cross chapter, & ask for the community hurricane preparedness plan, including information on the safest evacuation routes & nearby shelters. 2) Learn safe routes inland • Be ready to drive 20 to 50 miles inland to locate a safe place. • Have disaster supplies on hand: Flashlight & extra batteries, Portable, battery-operated radio & extra batteries, First aid kit & manual, Emergency food & water, Non-electric can opener, Essential medicines, Cash & credit cards, Sturdy shoes.

  45. Hurricane Preparedness, Before Hurricane Season Stars (8 points): • 3) Make arrangements for pets • Pets may not be allowed into emergency shelters for health & space reasons, so contact your local humane society for information on local animal shelters • 4) Make sure that all family members know how to respond after a hurricane • Teach family members how & when to turn off gas, electricity, & water • Teach children how & when to call police, or fire department & which radio station to tune to for emergency information

  46. Hurricane Preparedness, Before Hurricane Season Stars (8 points): • 5) Protect your windows • Permanent shutters are the best protection. A lower-cost approach is to put up plywood panels. Use 1/2 inch plywood - marine plywood is best - cut to fit each window. Remember to mark which board fits which window. • Pre-drill holes every 18 inches for screws. Do this long before the storm 6) Trim back dead or weak branches from trees.7) Check into insurance

  47. Hurricane Preparedness, Before Hurricane Season Stars (8 points): • 8) Develop an emergency communication plan. • In case family members are separated from one another during a disaster (a real possibility during the day when adults are at work & children are at school), have a plan for getting back together. • Ask an out-of-state relative or friend to serve as the "family contact." After a disaster, it's often easier to call long distance. Make sure everyone in the family knows the name, address, and phone number of the contact person.

  48. Make sure you are prepared! http://www.fema.gov/hazards/hurricanes/whatshouldido.shtm#before

  49. References:

  50. We wish to express our warm thanks to GDHNet faculties and all groups that contributed their valuable materials.

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