CASE STUDY HURRICANES AND TORNADOES

when did Hurricane Harvey occur?

August 2017

describe the development of Hurricane Harvey

• It started off as a tropical wave in the Caribbean then reached tropical storm status at it moved towards the Texas coast reaching Category 4- It intensified on August 24th over the Texas and Louisianan coastline, making landfall five times in four days, delivering record levels of rainfall

how many inches of rain fell in four days in Houston?

50 inches

what were primary impacts of Hurricane Harvey?

• at least 68 direct deaths due to freshwater flooding- flooding forced 39,000 people out of their homes and into shelters- More than 48,700 homes were affected by Harvey throughout the state, including over 1,000 that were completely destroyed and more than 17,000 that sustained major damage; approximately 32,000 sustained minor damage- Nearly three weeks after the storm, at least 3,900 homes were still without power

what were the secondary impacts of Hurricane Harvey?

• Causing about $125 billion in damage, Harvey ranks as the second-most costly hurricane to hit the U.S. mainland since 1900• During the storm, more than 800 Houston area flights were canceled• Hurricane Harvey damaged or disrupted operations at 40 wastewater treatment plants that serve nearly 169,000 people, which caused at least 25,000 gallons of sewage-tainted water to flood streets and waterways• Harvey's impact spread across the country as gas prices rose. Harvey forced 25 percent of oil and gas production to shut down in the region, affecting 5 percent of nationwide output

why was preparation for Hurricane Harvey considered a failure?• No evacuation order was issued• Flooding experts say the biggest government failure likely came in the years that preceded the storm as the city allowed developers to build new communities with little regard for flooding projections • In Houston, flooding experts attribute the flooding in large part to a lack of zoning laws that have encouraged explosive property development with little regard to the environmental impact developers paved over empty land that would have otherwise absorbed rainwater

what was the perception of risk before Hurricane Harvey?

Meteorologists were skeptical about the unheard of amounts of rainfall anticipated. One described the precipitation models as "off the charts outrageous". The estimations of over forty inches of rain were sure to devastate Houston and many cities across Texas. As Harvey approached the lower Texas coast, many unsubstantiated reports surfaced from random sources on social media predicting that thousands of Houston homes would be under water from torrential rainfall. Mayor Turner also released a statement begging Houstonians not to rely on unofficial weather reports and debunking the rumor that the city had called for an evacuation, which it had not. Although the unsubstan- tiated reports seemed outrageous, just like the predictions, many of the warnings heeded true — not only about Hurricane Harvey's intensity but also about the city's lack of preparedness.

describe the storm surge from Hurricane Katrina?

• 2005- 8.5m storm surge along the Mississippi Gulf Coast even though it was a category 3 hurricane when it made landfall- the high storm surge was due to the fact that only 24 hours before landfall it had been a category 5 hurricanes and the water pushed in front of it was trapped along the Louisiana coast where it could not escape

what were the hard engineering strategies that mitigated the impacts of Hurricane Katrina?

• The levee system in New Orleans, which was designed to protect the city from flooding, helped to mitigate the impact of the storm surge. Although some of the levees failed, the majority of the system held up and prevented even more extensive flooding. -Building codes in some areas required homes to be built to withstand hurricane-force winds, which helped to reduce wind damage.

describe the process of monitoring Hurricane Harvey

• more than 72 gourd before Harvey's landfall, warning signs started to become apparent - computer models correctly predicted that a strong tropical storm or hurricane would make landfall of Friday- the National Hurricane Centre accurately started to warn off the prospect of flooding form both rain and storm surge- at least one model was showing the potential of up to 50 inches of rainfall- the prediction changes dramatically on August 24th when the NHC called the new forecast concerning

what were the limitations to the predictions for Hurricane Harvey-

The wind-intensity forecast: On Tuesday and Wednesday meteorologists predicted that Harvey would make landfall as a strong tropical storm or low-end hurricane. Of course, Harvey came ashore as a Category 4 hurricane. It wasn't until Thursday that forecasters began to communicate the possibility that Harvey could be a major hurricane (Category 3 or higher) at landfall. This underscores the well-understood need to improve hurricane-Intensitv torecasts- The placement of the heaviest rainfall: Models arent yet good enough to know where the heaviest rain is going to focus - which makes it challenging for emergency responders to pre-position and prepare.- Trusting the model forecasts: On Thursday and Fridav, computer models were simulating so much rain. with peak totals of 40 to 60 inches. Meteorologists were sceptical about the unheard-of amounts of rainfall anticipated. It was described as off the charts outrageous

when and where did Hurricane Sandy take place?

Hurricane Sandy formed in October 2012, in the Caribbean Sea. Over the next few days it moved northward passing over Jamaica, Cuba and the Bahamas before turning towards the US East Coat.

how did preparation mitigate the impacts of Hurricane Sandy?

Evacuations along the East Coast took place particularly in New York, New Jersey and Connecticut. People stocked up on emergency supplies. Federal Emergency Management Agency coordinated emergy response efforts and prepared to provide aid and assistance

why was it impossible to prepare for Hurricanes Ivan?

It started in Grenada, an LIC with a GDP per capita of around $9000. The preparation for the hurricane was very poor due to lack of government funds and efforts and the hurricane caused 34 deaths and a lot of damage to buildings, electricity and communications

what was the failure of the evacuation for Hurricane Rita?

In 2005 hurricane Rita hit Texas as a Category 5 storm and its intensification caused a wave of panic. Local officials encouraged over two million people in Texas and Louisiana to evacuate leaving traffic at a standstill. Hurricane Rita changed course, landing in the Beaumont area, and 107 people died in the evacuation, most from heat-related problems. This disastrous evacuation order was one of the reasons the City of Houston did not issue an evacuation order for Harvey

when did the Moore tornado occur?

May 20th 2013

how long was the Moore tornado on the ground for?

39 mins

what was the EF classification of the Moore tornado?

EF5 200+mph

what were the primary impacts of the Moore tornado?

-$2 billion worth of damage- the tornado flattened on elementary school, but no fatalities occurred- hit another school where a wall collapsed and killed seven children- 24 killed- destroyed 300 homes- damaged over 1150 homes

how prepared was Moore for the tornado?

• Moore is an NWS certified 'Storm Ready City,' which means the city (1) has a 24-hour warning and emergency operation centre with multiple methods for receiving severe weather warnings and forecasts and for alerting the public, (2) has its own local weather monitoring system, (3) promises public readiness through community seminars and (4) has developed a formal hazardous weather plan which includes trained weather spotters and regular emergency exercises• As soon as the tornadoes warning was issued, Moore's system of 36 sirens went off, automated mass calls to phone numbers, text messages, emails and tweets went out, in addition to radio and Tv announcements • The tornado touched down 12 minutes after the warning went out• Many Moore residents had more than 30 minutes of lead time before the tornado struck densely populated regions of the city

what were the limitations to Moore's preparedness?

• Less than one-tenth of Moore's homes have basements or below-ground shelters. This is largely the result of the underlying geology of the region as the clay rich soil means building correctly engineered underground shelters could cost $15-20,000• There are no community shelters in Moore, and most large buildings are not equipped with shelters but enough to hold occupants

how effective as Moore's preparation?

• Below ground shelters are the less expensive route, and all 16 above-ground shelters in the tornado's path survived• But these structures are small, usually holding less than six people and are not appropriate for large groups of people gathered at a school or office building• People at the elementary schools and the medical centre which laid along the oath of the tornado, had no safe place to go other than into the interior of the buildings, as far away from the outside walls and windows as possible • An elementary school and a few homes nearby took a direct hit from EF5 winds and were completely obliterated but fortunately the school and most of the homes had been evacuated• Unfortunately, another elementary school hit just a few minutes later had not been completely evacuation and seven children were killed

what was the prediction for the Moore tornado?

For several days the National Weather Service had been forecasting a moderate risk of severe thunderstorms capable of producing baseball sized hail with damaging winds and the potential for a few tornadoes. On May 20th, a tornado warning was issued for Moore and Newcastle at 2:40pm and by 2:52pm doppler radar had detected signs of vertical axis rotation of a supercell

what is an example of protection against high winds in tornado alley?

• buildings in states such as Oklahoma, Texas and Kansas are often constructed with reinforced concrete or masonry walls, metal roofs and steel frames

how high can pressure gradients in tornadoes reach?

an estimated 25 millibars per 100 metres

what is an example of a tornado that caused explosive decompression?

• Joplin, Missouri tornado in 2011- one of the deadliest tornadoes in US history- 200 mph

what is an example of a tornado with devastating impacts from hailstones?

• 2017, Elk City, Oklahoma- hailstones as large as 10.8 cm in diameter, significant damage to homes, vehicles and other structures