Hurricanes, Cyclones, and Typhoons

Description of event

Hurricanes, cyclones, and typhoons are all tropical weather systems formed by overly warm water in tropical oceans. Each, characteristically, exhibits rotary circulation and can be described as a low-pressure system. In the northern hemisphere, rotation is counterclockwise. Tropical weather systems can be immense in size, with the average storm reaching 600 km in diameter. These weather systems also exhibit characteristically high wind speeds, reaching a sustained velocity of up to 350 km/h. Research has also shown an average low pressure of 950 mb, with a range of 870 to 990 mb at the storm’s center. Hurricanes are classified by the strength of their sustained winds. The Saffir-Simpson scale rates hurricanes on a scale from 1 to 5 ( Table 94-1 ).

Table 94-1

Saffir-Simpson Hurricane Scale

Adapted from National Weather Service National Hurricane Center. The Saffir-Simpson Hurricane Scale Available at: .

Category Sustained Winds Damage Description Example
Tropical storm 39-73 miles/h
64-118 km/h
1 74-95 miles/h 119-153 km/h Minimal No real damage to buildings; damage to unanchored mobile homes Allison, 1995
2 96-110 miles/h
154-177 km/h
Moderate Damage to building roofs, doors, and windows; considerable damage to mobile homes; flooding damage; trees down Bonnie, 1998
3 111-130 miles/h
178-209 km/h
Extensive Some damage to small residences and buildings; mobile homes destroyed; coastal flooding causing destruction to smaller buildings; damage to larger buildings; flooding inland Opal, 1995
4 131-155 miles/h
210-249 km/h
Extreme Complete roof failure on small buildings; major erosion; flooding well inland Hugo, 1989
5 156 + miles/h 250 + km/h Catastrophic Roof failure on residences and industrial buildings; building failures possible; flooding on shoreline structures Andrew, 1992

The structure of a tropical weather system is primarily defined around the eye and the eye wall of the storm. The eye is the storm’s center, and it may be up to 30 km in diameter. It is characterized as the area of lowest pressure, as well as by warmth, lack of precipitation, and air compression. The eye wall is an area extending, on average, 10 to 20 km from the center of the eye; there are thick clouds and heavy rain in the eye wall, and wind speeds are the highest there.

Hurricanes can be described as originating from a large number of thunderstorms. These storms arrange in a pinwheel formation, leading to heavy convection and precipitation, separated by areas of weaker uplift and less precipitation. As a hurricane continues to strengthen, temperature increases toward the center of the storm. The center of the storm is kept warm by the release of latent heat. In the center, mostly clear skies predominate with divergence and sinking air. Near the eye wall, the air rises, cools, and releases latent heat. This latent heat is the primary source of energy for further development. Latent heat requires warm water oceans, generally > 27 °C.

Pre-Incident actions

Planning for a tropical storm involves preparations for all of the threats associated with the storm: high winds, flooding, landslides, thunderstorms, and storm surge.

Preparations for tropical weather should be an ongoing activity, occurring throughout the entire year. Specific preparations may be made at the start of the season, whereas others may be implemented when storm activity is anticipated. Typical hospital emergency management plans are organized based on a time line that starts at the beginning of the storm season and continues through the arrival of storm-force winds and to the poststorm recovery efforts.

Facility infrastructure considerations are essential during construction or remodeling efforts. Hospitals in areas where storms occur should be constructed to withstand high winds and flooding. Storm shutters should be used to protect all exterior openings. Alternate power sources should be an essential component of the facilities infrastructure. Redundant communications systems with civil defense and emergency medical services are essential because multiple system failures can occur.

Another consideration for medical facilities, regardless of size, is the evacuation of patients and staff further inland and away from the predicted storm track. Therefore the facility’s evacuation annex should include relocation of patients to a distant facility.

At the start of the storm season, sandbags should be available to barricade low-lying doors susceptible to flooding. Damage control equipment should be available. Plywood sheeting for blown-out windows, two-by-fours for reinforcing doors and other structures that may be stressed by prolonged winds, and vacuums that can handle water (wet/dry vacuum) are essential. Facility engineers and damage control parties must be designated as essential personnel, and they must receive training on mitigation of storm damage. Generators should be fully fueled and maintained.

Before a storm, employees should be alerted to bring in personal items that may be required for a prolonged stay in the medical treatment facility. This should include food, bedding, and medications. Employees who are in the facility during the storm should ensure that their families and residences are prepared before the storm.

Enough durable and expendable medical equipment and pharmaceuticals should be stocked to allow for unsupported operations for up to 72 hours. Disposable equipment (e.g., suture sets) should be considered if sterilization systems should fail. Alternative means of cleaning, such as alcohol-based hand sanitizers, should be obtained. Food and water must be stocked to feed and hydrate staff, patients, and family members of patients. The fuel tanks of vehicles, both personal and hospital-associated, should be filled. Waste systems may be damaged, so alternative means of disposing of liquid and solid waste, including biohazard material, must be considered.

Traditionally, pregnant women, who are either at least 36 weeks’ gestation or are in the third trimester and expecting complications with delivery, have been advised to report to the hospital before the storm’s arrival. Precipitous labor may occur due to decreased barometric pressure, although this has never been validated.

During the Storm

Generally, damage control predominates during the passage of a tropical cyclone over a medical facility. In an intense storm, there will be minimal movement outdoors, so new patients will not be arriving in large numbers.

Local officials will determine the most effective and safest response method during tropical weather events. Conditions may become so severe that rescue and emergency medical services operations may cease for a period of time. Communications will deteriorate during the storm. Cellular systems will go down as repeater cells are destroyed. The same is true for handheld radios beyond the line of sight as their repeaters are damaged. Amateur radio operators may serve as a valuable source of redundant communication.

Deaths during the storm will occur due to multiple causes. The largest cause of death in flat areas is flooding. Oftentimes, these deaths involve the drowning of persons trapped in vehicles. In areas with hills, landslides may be the most prominent cause of death. Drownings from swimming, boating, or surfing in storm waters do occur, despite warnings to the contrary. Deaths that can occur poststorm may be indirectly due to power outages because people are electrocuted when power lines are reenergized, and, from the use of candles, which can lead to house fires. Equally frustrating are deaths related to carbon monoxide, resulting from the use of generators or charcoal stoves/grills without proper ventilation. ,

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Aug 25, 2019 | Posted by in EMERGENCY MEDICINE | Comments Off on Hurricanes, Cyclones, and Typhoons

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