Hurricanes Flashcards
Preconditions needed for Hurricane formation
-Sea temperatures at least 26.5 degrees Celsius to a depth of 45m
-Low vertical wind sheer
-Strong Coriolis effect
-Latitude between 5-20 degrees N/S of the equator.
Typhoon Haiyan stats
-Philippines has a population density of 380 people/Km^2
-On 8/11/2013, typhoon Haiyan made landfall in Tacloban
-It was a cat5 on the Saffir-Simpson scale, with wind speeds up to 195mph.
-6,352 killed
-28,781 injured.
-6million displaced
-$3 Billion in damages
-1 million homes destroyed.
-90% of Tacloban destroyed by a 5m storm surge
Typhoon Haiyan Prediction
-PAGASA (The Philippines meteorological agency0 had correctly predicted the storm surge.
-But, this information was disseminated in one line at the end of a routine weather report.
-The Japanese meteorological Authority had issued notices to the Philippines that a major storm was approaching the country, using their Himawari 6 satellite.
Typhon Haiyan Prediction changes and evaluation
-After haiyan PAGASA improved its weather severity models by increasing radar range.
-Project NOAH was expanded to enhance mapping and risk-analysis of disaster-prone areas.
-Weather report structure updated to make sure risk was properly conveyed.
-Storm surge warning developed.
-Improved forecasting accuarcy is helpful, but was not main issue for Haiyan
-Rural areas often neglected in emergency prediction measures, warnings may not reach these areas.
Typhoon Haiyan Preparation
-Many towns such as Tacloban completely neglected all warnings, and didn’t act on them.
-PAGASA’s field office in Tacloban didn’t evacuate, leading to one death.
-In 2017, just 23% of people indicated they had the necessary training to respond to a disaster in the country.
-Even when warnings were issued, there was insufficient evacuation shelters available.
-Leyte was the worst affected island but many chose to remain at home despite warnings.
-415 evacuation centres damaged.
-Only 8% of evacuation centres were suitable for use in another storm, many were inadequate single-storey buildings like schools.
Typhoon Haiyan Preparation changes and evaluation
-Stronger evacuation plans with statutory requirements in some areas.
-land-use zoning and building regulations brought in to reduce risk.
-Minimum stockpile of emergency goods for future disasters
-Many of the ‘Build Back Better’ schemes have been delayed or failed.
-Building regulations are good but often poorly enforced.
-Evacuation centres continue to be poorly located. In Marikina (N.Philippines) 80% of centres are still in high-risk zones.
Typhoon Haiyan monitoring
-The monitoring was a world-class demonstration of international collaboration, even if it didn’t convey the importance of the information in time.
-The Met Office provided emergency meteorological information to PAGASA, though the lack of prior agreements (preparation) made this difficult.
-Volunteers for OpenStreetMap quickly mapped many of the worst affected areas.
Typhoon Haiyan monitoring changes and evaluation
-proposed creation of a Department of Disaster Resilience to strengthen monitoring and responses.
-NDRRMC promotes improved cooperation between agencies.
-International satellite data-sharing network (Involving MET-Office).
-Investment in local Government offices to decentralise response/decisions.
-Proposed DDR is still yet to be established 12 years on.
-Local corruptions means that communication and relief dissemination is problematic.
-Some local governments continue to lack disaster capacity-even in Manilla, the capital.
Hurricane Harvey Stats
-Made landfall on the 25/8/2017 in Texas as a cat3 before being upgraded to a cat4.
-Wind speeds recorded up to 130 mph, but monitoring equipment was disabled so true speeds are likely higher.
-Due to an unusual pressure system, the hurricane stalled over Texas for 4 days. Some areas received over 40 inches of rainfall in 48 hours.
-Harvey leaves Texas on the 29/8/2017 before carrying on to Louisiana and dissipating on the 2/9/2017.
-Up to 12ft storm surge seen in port Aransas.
-107 deaths, with 103 in Texas.
-194,000 homes damaged or destroyed
-$125 Billion in damages.
Hurricane Harvey Prediction
-The national Hurricane Centre (NHC) is a Division of NOAA and is in charge of forecasting and issuing warnings of tropical cyclones that may impact the US.
-GOES West monitors the Atlantic ocean and was used in predicting Harvey.
-The NHC issues public forecasts every 6 hours.
-The NHC also gives live interviews to news outlets and TV stations in areas that were at risk. Briefings were done in Spanish and English.
-Warnings from the NHC were continuously issued before and during the disaster, including rainfall predictions, wind speeds and reminders of catastrophic flooding.
-23/8, the NHC predicts rainfall between 10-15 inches and warns that ‘Rainfall from Harvey could produce life-threatening flooding’
-24/8, the prediction was upgraded to 12-20 inches and an extreme wind warning of 115-145 mph winds.
-Warnings stated ‘Life-threatening storm surge and freshwater flooding expected’
Hurricane Harvey prediction changes and evaluation
-The NHC accurately predicted Harvey’s rapid intensification, landfall location, and extreme rainfall.
-Advanced Satellite imagery, weather models and radar data helped track the storm’s path and intensity.
-The storms extreme rainfall (50+ inches in some areas) exceeded most predictions, which highlighted the need for better forecasting of slow-moving storms.
-The NHC has since enhanced the rainfall prediction models and improved public communication about flood risks.
Hurricane Harvey preparation
-The Governor of Texas declared a state of emergency for 30 of the counties in Texas 2 days before Harvey made landfall.
-Mandatory evacuations issued for 12 counties, others given voluntary evacuations.
-Houston fire station rescue resources in areas that were prone to flooding.
-A state of emergency was declared for the whole of Louisiana
-500,000 sandbags were prepared by the national guard.
Hurricane Harvey Preparation changes and evaluation
-Texas followed the state of Texas emergency management plan, and had designated evacuation zones for hurricane-prone areas.
-Evacuations were issued in some areas and shelters were set up quickly.
-Houston’s mayor didn’t order a full evacuation due to the large population (2 million people) making a short notice evacuation impractical.
-Many homes were built in flood-prone areas without adequate flood defences. In response, there are now stricter building codes and flood mitigation projects in Houston.
Hurricane Harvey monitoring
-The NHC oversees monitoring hurricanes in the US.
-The GOES-13 satellite provided visible and infra-red images to track the development and intensity of the hurricane as it developed.
-The Suomi NPP satellite measured the state of the atmosphere using sea surface temperatures, atmospheric temperatures and moisture.
-Data from the ABI and Suomi NPP satellite was used to create flood maps which were used to guide response.
-The Air force reserve hurricane hunters flew into the eye of the hurricane 10 times, collecting data such as wind speed and direction, dew point, pressure and temperatures. This data was passed to the NHC every 10 minutes.
