Wind-Related Storms (Tropical Storms, Hurricanes, Tornadoes, Severe Winter Storms, etc.)
These storms create varying degrees of wind and wind damage and varying degrees of rain and flooding. The problems of flooding and Best Practices have already been discussed in the “Floods” section. This discussion will be about wind, wind damage, and means of mitigation.
Severe winds may cause high levels of water to accumulate and inundate areas. Wind depending on the speed, type, direction, and length of time of the event, may cause serious injuries and deaths as well as devastating destruction to communities, road systems, utilities, schools, and other public buildings, homes, and businesses.
There are various types of meteorological events which produce high and sustained winds including:
- 1. Mid-Latitude Cyclones—These are extremely large weather systems with low-pressure areas, most frequently occurring during the winter, around which the winds flow counterclockwise in the northern hemisphere and clockwise in the southern hemisphere. North Easters and blizzards may be caused by these weather systems and may create extremely hazardous conditions for extended periods of time. (See endnote 21.)
- 2. Tropical Cyclones—These are various low-pressure systems with maximum winds of
- 73 mph.
- 3. Tropical Depression—This is a low-pressure tropical system that forms over warm water with maximum winds of 38 mph and may produce extremely large amounts of rain leading to severe flooding.
- 4. Tropical Storm—This is a tropical system with sustained winds of 39-73 mph that may produce extremely large amounts of rain leading to severe flooding while causing some beach erosion and damage. (See endnote 20.)
- 5. Hurricane—This is a tropical cyclone or system which has defined wind circulation that develops over the tropics drawing its energy from the warm water, producing winds of
- 74 mph or greater and causing heavy sustained rain, destructive winds depending on the speed, and storm surges which may inundate and destroy property. Differential pressures from the storm may destroy windows and doors especially garage doors, roofs, and walls. Severe injury and death may be the result of the force of the winds, the debris found in the winds, falling trees, downed electrical wires, drowning from the flooding, etc. The gale force winds can extend hundreds of miles from the center which is called the circular eye. There are five categories of hurricanes listed on the Saffir-Simpson hurricane wind scale as follows:
a. Category 1—These are dangerous sustained winds of 74-95 mph which may produce some damage to roofs, siding, trees, and power lines.
b. Category 2—These are extremely dangerous winds of 96-110 mph which may cause serious damage to roofs, siding, and trees, and near total power loss.
c. Category 3—These are extremely dangerous winds of 111-129 mph which may cause devastating damage to roof decking and gabled ends of housing, trees, electricity, and water.
d. Category 4—These are extremely dangerous winds of 130-156 mph which cause catastrophic damage to houses, trees, and power poles, and create power outages that could last for weeks.
e. Category 5—These are extremely dangerous winds of 157 mph or higher causing catastrophic damage including destroying homes, trees, and power poles with resultant power outages lasting weeks to months. The affected area they become uninhabitable for long periods of time. (See endnote 22.)
- 6. Thunderstorms—These may be extremely dangerous weather systems that affect small areas, usually 15 miles in diameter, lasting about 30 minutes, and composed of moisture and unstable air that is lifted skyward by cold or warm fronts, sea breezes, air warmed by the sun’s heat, or mountains. Although there are about 100,000 thunderstorms each year in the United States, all of which are considered to be dangerous, about 10,000 are classified as severe and are very dangerous. Along with the wind and rain, thunderstorms create lightning which is extremely hazardous because it causes human fatalities and injuries, wildfires, and destruction of property at a cost greater than $1 billion in insured losses each year. Straight-line winds, which are not associated with the rotation of a tornado but associated with the thunderstorm, can exceed 125 mph and cause massive damage.
- 7. Tornados—These are violently rotating columns of air which extend from a cumuliform cloud, such as a thunderstorm, to the ground. The funnel becomes visible when dust and/ or debris are picked up by the storm. The amount of destruction of the tornado is based on numerous factors of time on the ground, size of the tornado, condition of properties, etc. and the 3-second wind gust as measured by the Enhanced Fujita Scale (EF-Scale) used by the National Weather Service as follows:
a. EF-Scale Rating 0: 65-85 mph
b. EF-Scale Rating 1: 86-110 mph
c. EF-Scale Rating 2: 111-135 mph
d. EF-Scale Rating 3: 136-165 mph
e. EF-Scale Rating 4: 166-200 mph
f. EF-Scale Rating 5: over 200 mph (See endnote 23)
A waterspout is a weak tornado that forms over water usually over the Gulf Coast. Usually it dissipates over land but may cause damage and injuries.
Best Practices for Wind-Related Storms (See “Floods” section above)
- • Develop a comprehensive plan for removal of people and pets to appropriate secure and safe areas in occupational settings, school settings, and home settings, and use practice drills to determine the efficacy of what is being done. Each setting should have emergency phone numbers, cell phones, smoke alarms, carbon monoxide alarms, fire extinguishers, water, emergency first aid kits, food, flashlights, and cleaning supplies for people and facilities.
- • Develop and frequently test a disaster plan for external community disasters where people have to go to hospitals and other healthcare settings and a disaster plan for serious damage to the hospital and other healthcare settings where people have to be moved to other facilities.
- • Develop a plan for each school which ensures that everyone takes cover in a safe area as determined by registered engineers or safety specialists within 60 seconds in the event of a tornado or other severe weather system. Delay lunches or assemblies in large rooms because the roofs are very vulnerable. Keep children at the school even beyond normal school hours until the emergency has passed.
- • Communities should develop a comprehensive search, rescue, cleanup, and people assistance plan with alternative approaches in the event that parts of the plan are inoperable.
- • Develop an up-to-date list of individuals who are very young, disabled, or elderly and need assistance in the event of an emergency and have close-by friends, neighbors, or family prepared to help the needy individual.
- • Communities should test and utilize a severe weather notification system by means of all types of communication systems including sirens, special weather radios, announcements from the National Weather Service, the internet, and police and firemen going door-to-door depending on the type of weather emergency, etc.
- • Where feasible in areas where there are regular periodic severe weather systems, utilize if possible an underground shelter, safe room or area of the house where there are no windows and the structure is built in a substantial manner.
- • Immediately leave mobile homes when instructed to in the event of a tornado, hurricane, or flood warning and go to the nearest substantial shelter.
- • If caught outside during severe weather, make sure that your seatbelt is buckled and pullover into a safe area until the storm passes.
- • Evacuate all areas when ordered to do so by the appropriate authorities prior to the onset of a hurricane.
- • Do not go outside unless it is a life-and-death situation prior to, during, and in the immediate aftermath of a hurricane.
- • Provide food, medicine, etc. for all pets and secure them.
- • Evaluate before storms the potential for windstorm damage to the home including windows, doors, garage doors, roofs, etc., utilizing the Homeowner Windstorm Damage Mitigation Checklist. (See endnote 24.)
- • In severe winter weather, dress appropriately with layered clothing and protection for the head and extremities and remain in the low temperatures for very short periods of time.