A policy statement of the American Meteorological Society as adopted by the Council on 13 January 1991
Mobil-home living is a way of life for a significant portion of the population of the United States. As estimated 13 to 15 million people permanently reside in an estimated 6 to 8 million mobile homes throughout the country. Additionally, another 1.7 million are occupied on a part-time basis.
It is of grave concern that the American Meteorological Society observes that tens of thousands mobile homes (also known as manufactured homes) are damaged each year by windstorms to the extent that insurance claims are filed. Further, the flying debris produced by mobile homes during windstorms often inflicts damage to surrounding property, thus compounding the problem. Injuries and fatalities from high wind events also occur in a disproportionately high number to individuals occupying mobile homes. For example, statistics kept by the National Severe Storms Forecast Center for the 5-year period from 1985-89, show 37% of the tornado fatalities are persons who are either in or fleeing from a mobile home residence.
Hurricane and tornadoes are sometimes perceived by the general public as the only weather events that cause major destruction to mobile homes. However, this perception is clearly false since many weather events are capable of producing surface winds that exceed the 31 m s -1 (70 mph) damage threshold for mobile homes. In particular, straight-line winds from thunderstorm outflows often produce areas of (tornado-like) damage to mobile homes. The spatial and temporal scales of these damaging outflow events are quite variable, ranging from "mesoscale convective systems" that may produce continuous or intermittent swathes of wind damage over several states, to short-lived convective outflows called "microbursts" that may only last 2-5 minutes and affect a path length less than 4 km (2.5 miles). Current research suggests that microbursts can occur throughout the country and are sometimes found in association with innocuous appearing cumulus clouds without heavy rainfall reaching the ground the ground or the thunder, lightning, and hail often associated with high wind events.
Wintertime frontal and cyclone systems, particularly near coastal regions, can also have wind speeds that exceed the wind damage threshold. These frontal and cyclone events can affect large portions of a state or many states for time periods of several hours or greater. In addition, near foothills and mountain areas, severe downslope winds lasting 6 hours or more can batter structures with wind gusts up to 55 m s -1 (120 mph). These windstorms often affect areas as large as a 25-30–km (15-20–mile) wide band for 160 480 km (several hundred miles) along a mountain range.
Death, injury, and property damage in the wake of severe windstorms have prompted efforts to encourage owners of large mobile home parks to construct storm shelters. Such activity is considered essential for individual safety. Also, efforts at the local level to develop regulations governing tie-downs have proven effective as a property-protection measure in wind prone areas.
Recommendations: As a property-protection measure, the American Meteorological Society urges that mobile homes be anchored properly to the ground. The Society also urges mobile home residents to become familiar with procedures to follow in the event of severe weather, since injuries can occur in severe wind events even when proper tie-down procedures are used.
Residents must be prepared to evacuate their dwelling and seek a safer location in the event of a tornado or high wind warning. The Society suggests that adequate shelters be constructed at mobile home parks as a precaution against injury and death. Information on proper tie-downs and shelters may be obtained from governmental sources through the nearest office of the State Division of Emergency Services (Civil Defense), or from corporations specializing in mobile home tie-down equipment and installation. Appropriate government agencies are urged to distribute relevant information periodically, such as procedures to follow in the event of severe weather and information on the construction of tie-downs and shelters, to residents of mobile homes. Since mobile home residents face a unique threat during high wind events, warning sirens or some other local notification system would prove useful to alert residents of impending wind danger. Residents in wind prone areas may also wish to purchase a National Oceanic and Atmospheric Administration (NOAA) weather radio.
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