Hurricanes are far deadlier than tornadoes, and their effects are far more lasting. A single storm is capable of killing tens of thousands of individuals, especially when they hit developing countries with less ability to evacuate and prepare citizens. Massive amounts of rain can cause mudslides, burying entire villages. Tidal surge has been known to wash towns into the sea. The wind alone can cause catastrophic damage.
A hurricane may move slowly - some move only 9 miles per hour. This can leave a storm 'sitting' over a single coastal area for 18 hours or more, relentlessly beating the shore with waves, wind and tide. One hurricane may hit several countries or states within a region. It may last more than a week as it travels across the sea, leaving a path of death and destruction in its wake.
A quick review of recent history adequately displays the ferocity of hurricanes. Even the most ardent skeptic can not deny the death toll of these storms can be staggering. Often, these are just numbers we hear on the CNN. How many of us remember the 11,000 dead, and 8,000 missing, in Honduras and Nicaragua after Hurricane Mitch in 1998? What tornado has ever taken such a toll?
Once the storm has passed, the hurricane's death toll continues to rise. People are left without food or potable water. They may be marooned on boats, stuck under walls of mud, or injured by flying debris. Levees and dams fail under the pressure of rain and flood water, creating virtual lakes out of low-lying land. The inhabitants are asea in flooded homes, seeking refuge on their rooftops. Think of all the images of Katrina victims, lifted from rooftops by helicopter days after the storm had moved inland.
Disease thrives in such a situation. Lack of power and road damage reduces access to medical care. Inadequate refrigeration destroys some life-saving medicines. Stagnant water is a breeding ground for bacteria and malaria-bearing mosquitoes. Dehydration and dysentery strike indiscriminately. Decaying bodies, undiscovered for days or weeks, add to the miasma of biological threats. Buildings left sitting in flood water disintegrate on their foundations, threatening to collapse on those seeking shelter. Molds grow on every available surface. The heat continues, without the benefit of air conditioning and fans, causing trouble even for rescue personnel. It may take months to return a community to a safe standard of living, and years to return it to full functionality. One only has to consider New Orleans; two years later, it is still a shadow of it's former self.
Some argue that the advanced warning a hurricane affords a community makes them less of a threat than a tornado. While the advance warning does, in fact, save lives, giving people more time to prepare and/or leave the area, it does not significantly reduce damage over a widespread area. Hurricane force winds, tidal surge and aggressive wave action can spread over hundreds or thousands, of miles, creating havoc for several states or neighboring countries. Evacuations are not fool-proof as these storms are so unpredictable - even government approved evacuation centers can become deathtraps when storms take an unexpected turn.
Many people don't realize that hurricanes often carry a flurry of tornadoes in their wakes, further adding to the misery of people trapped in homes, trailers, cars and evacuation centers. This weakens the debate somewhat as tornadoes can't be completely separated from hurricanes, but it does add to the over all lethal effect of these named tropical cyclones. Tornadoes are more abundant and less predictable, but hurricanes clearly claim more lives.