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HurricanesIn September 2003, Hurricane Isabel caused 32 deaths and approximately $1.9 billion in damages to homes, businesses and public facilities in Virginia, affecting 75 percent of the state. Yet, this deadly storm was only a Category 1 hurricane when it reached Virginia.
Hurricanes aren’t the only tropical systems that warrant caution. Tropical Depression Gaston (2004) and Tropical Storms Jeanne (2004) and Floyd (1999) all caused major damage and prompted federal disaster declarations.
Tropical depressions, tropical storms and hurricanes are low pressure areas that develop in the tropical regions of the ocean (between 20 degrees N latitude and the equator). These storms are masses of thunderstorms that organize and begin to rotate. These systems, in order of intensity, are called depressions (winds between 25 and 38 mph), tropical storms (winds between 39 and 73 mph) and hurricanes (winds of 74 mph or greater).
The National Weather Service tracks these storms on charts during hurricane season, June 1 through Nov. 30, using the following symbols.
A tropical depression, the lowest intensity, is given a number once it has a counterclockwise spin and winds of 38 mph or less.
When wind speeds reach 39 mph and the storm is given a name from a pre-determined list, a tropical storm is born. While a tropical storm does not produce a high storm surge, its thunderstorms can still pack a dangerous and deadly punch. In 1972, Agnes was only a tropical storm when it dropped torrential rains that led to devastating floods in Pennsylvania, Maryland and Virginia. Sixteen people died in Virginia and damage was estimated at $222 million.
A hurricane is the most intense tropical event, with five categories and winds ranging from 74 mph to 155 mph or greater. Storm surge is a major concern with hurricanes. The extremely high winds cause ocean water to pile up, creating higher than normal sea levels with waves up to 40 feet in open water. High sea levels and shallow waters can devastate a coastline and bring ocean water miles inland.
A hurricane's bands of thunderstorms produce torrential rains and sometimes tornadoes. A foot or more of rain could fall in less than a day, causing flash floods and mudslides. Large rivers in the hurricane's path might still be flooding for days after the storm has passed. The storm's driving winds can topple trees, utility poles and damage buildings. Communication and electricity might be lost for days and roads are often impassable due to fallen trees and debris.
Though it might seem that only the shoreline is vulnerable to the effects of hurricanes, all of Virginia can be affected by tropical systems. As we saw in 2004 with Tropical Depression Gaston and Tropical Storm Jeanne, even weakened storm systems can cause problems for inland areas. Both of these storms resulted in federal disaster declarations, loss of life and tremendous property damage.
Hurricanes are rated on the Saffir-Simpson Hurricane Scale based on the storm's intensity. This 1 to 5 rating scale estimates potential property damage. Hurricanes reaching Category 3 and higher are considered major hurricanes because of potential for loss of life and damage, though Category 1 and 2 storms are still very dangerous and should not be taken lightly.
The flooding and high winds associated with hurricanes may also disrupt the distribution of gasoline, kerosene, diesel fuel, fuel oils, propane and other petroleum products. This disruption could cause major problems for organizations and businesses that rely on such supplies. Additionally, such a disruption could affect backup power generation.
Know the difference between "watches" and "warnings."
Local and state officials, along with the National Weather Service, make the decision to issue an evacuation order. In making this decision, officials consider:
Read about responding to hurricanes.
