hurricanes and the coastline severe weather hazards
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Severe Weather Hazards & Hurricanes and the Coastline
Min Gu Kim and Vicky Yeung, EE60N November 6, 2018
Severe Weather Hazards
Severe Weather Hazards
Tornadoes
Northeasters
Hurricanes
Severe Weather Hazards
Tornadoes
Tornadoes | Basics
- Bodies of air with a funnel shape rotating counterclockwise- Low interior pressure and high velocities in walls - Damage the smallest area through mobilizing debris
- Tornado swarm: tornado breakout - Occur March to July, mainly in Tornado Alley
Tornadoes | Formation
http://web.gccaz.edu/~lnewman/gph111/topic_units/thunder_hurr/thunder_hurr2.html
Tornadoes | Tornado Alley
https://en.wikipedia.org/wiki/Tornado_Alley#/media/File:Tornado_Alley_Diagram.svg
Tornadoes | Monitoring
Tornado Watch: tornado-breeding thunderstorms
Tornado Warning: tornadoes spotted or Doppler radar identifies hook-shaped areas
Severe Weather Hazards
Tornadoes
Northeasters
Northeasters | Basics
- Refers to direction from which their winds come - Massive extratropical storms originating in mid-latitude, move
eastward and track up the Atlantic coast - Low-pressure systems with counterclockwise winds - Occur October - April
Northeasters | Formation
https://www.boatus.com/magazine/2016/december/anatomy-of-a-noreaster.asp
Northeasters | Formation
Northeasters | Dolan and Davis Scale
Severe Weather Hazards
Tornadoes
Northeasters
Hurricanes
Hurricanes | Basics
- Massive tropical storm system with rotary winds >119 km/hr- Storms in the NW Pacific are called typhoons or cyclones in the
Indian Ocean - Cape Verde storms: form in E. Atlantic off the coast of Africa - “Hurricane season”: June to November
Hurricanes | Formation
https://www.vox.com/science-and-health/2016/10/6/13191010/how-hurricanes-form-tropical-storms-guide
Releases enough energy to supply US energy demands for 6 months!
Hurricanes | Structure
https://en.wikipedia.org/wiki/Tropical_cyclone
- Two velocities:- Storm center velocity:
Forward speed of the storm
- Hurricane wind velocity: rotational speed of the winds circling the eye
- Right side: velocity = hurricane wind velocity + storm center velocity
- Left side: hurricane wind velocity - storm center velocity
Area of low pressure
Strongest winds
Bands of torrential rain and high winds
Hurricanes | Monitoring
- Ships at sea transmit weather reports - Scientists at National Hurricane Center scan satellite images of
Earth every 30 mins to watch for disturbance- For matured storms: observation planes examine close up and
land-based radars examine structure of storm - Hurricane hunters fly into the storm and drop dropsondes which
transmit meteorological data
Hurricanes | Monitoring
Coast-parallel hurricane track: weaker left side moves over land
Coast-normal hurricane track: moves onto coast at right angle. Severe damage on right side, less severe on left side
https://www.wunderground.com/hurricane/atlantic/1960/Major-Hurricane-Donna
Hurricanes and the Coastline
Hurricanes | Damage Potential Scale
https://www.entergynewsroom.com/media-kit/hurricane-wind-scale/
Looking closely to Category 5
Hurricane captured from the spaceThis is what happened after Hurricane Andrew passed by
Coast l Hurricane and Effect on CoastlinesHurricanes and the Gulf of Mexico Coastline
- Galveston, Texas is a coastal resort city (island)- Galveston is built on a low-lying island, a sandy barrier beach- Texas has an immense area of low-elevation coastal land. These lands lie less than
20ft above seal level. The surges and high waves accompanying hurricanes wreak havoc on low-lying areas.
- Category 4 hurricane struck the bay (thousands were killed)- Due to decaying human bodies the spread of disease was a problem- Afterwards, the city constructed a 5km long seawall, 17 ft high and 16ft wide and sand
was brought in to elevate the island
Paths of 10 hurricanes that hit the Texas coast between 1960 and 1979
Hurricanes and the Atlantic Coastline
- Category 4 hurricane (Hugo) struck Charleston, South California- Although Hugo was a powerful hurricane, it caused only 11 death. Property damages
exceeded $7 billion. Here is the trend - decreasing deaths, increasing damages. - An ongoing trend is for Americans to move to the coastline and to build larger and more
expensive homes filled with more expensive possessions.
- Death by hurricanes in the United States have dropped dramatically due to the advance warnings that are now broadcast widely before a hurricane make landfall.
Hurricanes and the Pacific Coastline
- The Hawaiian Islands lie on the northern edge of the warm, hurricane generating waters of the Pacific Ocean
- Usually cold water drains the energy out of any hurricanes that dare to move across it
- Fast-moving category 4 Hurricane Iniki hit Kauai- No building escaped damage, over 6,000 utility poles snapped like
matchsticks, and even bark was stripped from many trees- Although only two people were killed, the island economy suffered over $2
billion in damages
Evacuation Dilemma
- Since population growth is far faster than the building of new roads and bridges, it’s hard for people to evacuate
- It is estimated that evacuating some cities could take 72 hours - We do not get notices three days in advance where a hurricane will strike- The detailed path of a hurricane is still unpredictable
How can we reduce Hurricane damages?
- When hurricane winds destroy a building, a common first step is lifting off the roof so better designing the buildings with connecting roofs to the wall is essential.
- Winds that come inside the building intensifies destruction so shatter-proof glass and door is crucial
- Using low-lying coastal land as farm fields, parks, golf course, and etc. And the higher and more protected land could be zoned for house and building construction
- Adding sand to beaches, adding riprap, or building hard walls
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