The terms "hurricane" and "typhoon" are regionally specific names for a strong "tropical cyclone". A tropical cyclone is the generic term a low-pressure system over tropical or sub-tropical waters with organized convection (i.e., thunderstorm activity) and definite cyclonic surface wind circulation¹.

Tropical depressions are tropical cyclones with maximum sustained surface winds (10 min. average) of less than 17 m/s (34 kt, 39 mph). (This is not to be confused with the condition mid-latitude people get during a long, cold and gray winter wishing they could be closer to the equator ;-))      -- not my joke!¹

Tropical storms are tropical cyclone with winds of at least 17 m/s (34 kt, 39 mph), and out of respect for their potential they are assigned a name.

Hurricanes (that is what the storms are called if they are in the North Atlantic Ocean, the Northeast Pacific Ocean east of the international dateline, or the South Pacific Ocean east of the 160th meridian) and Typhoons (if in the Northwest Pacific Ocean west of the dateline), and "Severe Tropical Cyclones (in the Southwest Pacific or Indian Ocean) are the same. They are cyclonic storms which sustain winds of 33 m/s (64 kt, 74 mph) or more.

These storms derive their energy in part from the evaporation of warm sea water in the presence of high winds. Combining lowered surface pressure, the associated condensation, energy and clouds concentrate near the storm's center. Structurally, tropical cyclones have their strongest winds near the earth's (or ocean's) surface as a consequence of rising air in their "warm-core". "Warm-core" just means that the center of the storm is relatively warmer than the air farther away.

What all this boils down to is a group of storms, ranging from relatively small (100 miles across), to giants (more than 1500 miles across), bringing strong winds and rain from the sea to the shores. Fully developed hurricanes have a well-defined eye surrounded by a circle of the highest speed surface winds. The eye may be 30 miles across, and is calm, warm air rising through the center or the storm.

The range of effects of a hurricane and related storm may be from almost none -- to catastrophic -- depending on the storm's speed of movement. A fast moving strong compact storm can go through an area with little damage. The slow moving tropical storm with weak wind may dump lots of flooding rain. North of the equator most of a storm's damaging wind and rain is in its "right-front" quadrant. To better understand what this says, draw a line showing the direction a storm has moved and extending this as its projected path. Now draw a crossing line where the storm is, in effect dividing the storm's position into 4 equal parts. The quarter in front of the storm, to its right hand side as the storm moves forward, is where most of the damage potential is (excepting the actual eye of the storm) can be found. It is in this portion of the hurricane where tornadoes are most likely to be spawn.

Hurricanes bring a "Storm Surge", a large dome of water often 50 to 100 miles wide to coastline near where a hurricane makes landfall. The surge of high water topped by waves can be devastating. The stronger the hurricane and the shallower the offshore water, the higher the surge will be. Timing is important: if the surge arrives at high tide, the water height will be even greater. The storm tide is the combination of the storm surge and the normal astronomical tide. Along the immediate coast, storm surge is the greatest threat to life and property.

Widespread flooding is caused by heavy torrential rains. This often exceeds 6 inches of rain in a 4 hour period. Sometimes more than 30 inches of rain fall during a storm's passing. This is the major threat to areas well inland. This rain can produce deadly and destructive floods. Normally small streams and rivers will run backward, pushed back by the flooding of lower ground. Even though hurricanes weaken rapidly as they move inland, they may cause rain to fall for days. The resulting floods have caused great damage and loss of life.

Hurricane-force winds destroy buildings and mobile homes. Debris, such as signs, roofing material, siding, and small items left outside, become flying missiles in hurricanes. Winds often stay above hurricane strength well inland. In 1989 Hurricane Hugo blasted Charlotte, North Carolina (which is about 175 miles inland), with gusts to near 100 mph, downing trees and power lines and causing massive disruption.

Tornadoes produced by hurricanes add to the destructive power. These often occur in thunderstorms embedded in rain bands well away from the center of the hurricane.

All of the Americas' Atlantic and Gulf coastal areas are subject to hurricanes or tropical storms. Parts of the Southwest United States and Pacific Coast suffer heavy rains and floods each year from the remnants of hurricanes spawned off Mexico.

Consider this before, during and after a hurricane. Safety rules and planning will make things easier for you during a hurricane. Forethought could help save your life and the lives of others.

Experts agree that many homes can survive a hurricane's fury if a few relatively minor improvements, such as bracing the gable ends of roofs, are made. Contact your builder, a professional engineer, licensed contractor, an architect, or city officials to inspect your home for structural integrity.

Stay or Leave?

You have to make the decision whether you should evacuate or whether you can ride out the storm in safety at home.

If local authorities recommend evacuation, you should leave! Their advice is based on past experiences and their knowledge of the strength of the coming storm, its potential for death and destruction in your area.