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