Active Hurricane Season Expected for 2002

What is a Hurricane?
A hurricane is a type of tropical cyclone—a generic term for a low pressure system that generally forms in the tropics. The cyclone is accompanied by thunderstorms and, in the Northern Hemisphere, a counterclockwise circulation of winds near the earth’s surface. Tropical cyclones are classified as follows:
Tropical Depression: An organized system of clouds and thunderstorms with a defined surface circulation and maximum sustained winds of 38 mph or less.
Tropical Storm: An organized system of strong thunderstorms with a defined surface circulation and sustained winds of 39-73 mph.
Hurricane: An intense tropical weather system of strong thunderstorms with a well-defined surface circulation and maximum sustained winds of 74 mph or higher.

Hurricanes are categorized according to the strength of their winds. A Category 1 storm has the lowest wind speeds, while a Category 5 hurricane has the strongest.

Lower category storms can sometimes inflict greater damage than higher category storms, depending on where they strike and the particular hazards they bring.

In addition, tropical storms can produce significant damage and loss of life, mainly due to flooding.

Source: NOAA National Hurricane Center

Professor William Gray, and his team of hurricane forecasters at Colorado State University, think 2002 is shaping up to be an active year in the tropics, with at least four major storms expected to develop during the season.

According to Colorado State University, Gray and his team issue early extended-range tropical storm forecasts every December for the following year’s hurricane season. For the 2002 forecast, the research team employed a new forecast scheme, one that places more emphasis on circulation features of the middle latitudes and discontinues the use of African rainfall information, which has not been a reliable forecast tool in recent years. Among the factors used in the new forecast scheme are the Quasi-bienniel Oscillation (QBO)—equatorial east-west stratospheric winds that vary with a period of 26-30 months; a measure of Atlantic Sea surface temperature; and a prediction of El Nino conditions for 2002.

Thirteen named tropical storms are expected to form in the Atlantic Basin between June 1 and Nov. 30, according to Gray and his team. The group anticipates that of the 13, eight will become hurricanes and four will grow into intense major hurricanes with sustained winds of 111 mph or greater. On average, major hurricanes account for about a quarter of all named storms, but when normalized for population, inflation, and wealth per capita, they account for about 85 percent of the destruction generated by tropical storm activity.

The term hurricane is derived from the name for the Caribbean god of evil, Hurican. According to the National Oceanic and Atmospheric Administration (NOAA), during an average 3-year period, roughly five hurricanes make landfall on the U.S. coastline, killing approximately 50 to 100 people anywhere from Texas to Maine. Two of the five are typically “major” or “intense” hurricanes, those with winds greater than 110 mph. Between 1900 and 1999, 23 hurricanes each caused damage in excess of $1 billion (adjusted for inflation). Damage from Hurricane Andrew (1992) alone was estimated at more than $25 billion in South Florida and Louisiana, a number that would likely have been higher had the storm hit Miami directly.

In a statement, Gray said the “upcoming hurricane season appears to us to have the potential for continued above-average hurricane activity.” He added that “an increased level of hurricanes” is expected to form in the deep tropics and hurricane activity will begin earlier in 2002 than it did in 2001.

During the last century the average probability of a major hurricane hitting somewhere along the U.S. coastline was 52 percent for any given year. For 2002, the probability jumps to 86 percent. The researchers estimated that U.S. Gulf of Mexico coast has a 43 percent chance of major hurricane making landfall. The last century annual probability for the Gulf Coast was 31 percent. For the Florida Peninsula and the East Coast, these numbers are 58 and 31 percent respectively.

“A great upturn in Atlantic basin hurricane activity has occurred the last seven years. It has been remarkable,” said Gray. The period of 1995-2001 was the most active seven consecutive Atlantic basin hurricane years on record, with 94 named storms, 58 hurricanes and 27 major hurricanes. Gray pointed out, however, that of the 27 Atlantic basin major hurricanes (Saffir/Simpson category 3-4-5 hurricanes) of the last seven years, only three (Opal, Bret and Fran) have crossed the U.S. coastline.

Gray said that over the last few years the U.S. has been lucky, noting that the country “should have experienced about nine major hurricane landfall events in the past seven years. We have also had 19 consecutive Atlantic basin hurricanes (since Irene of 1999) without landfall. The probability of this happening is less than one in a thousand.”

He predicted that the expected increase in hurricanes reaching U.S. soil would eventually come to pass. The rapid growth of U.S. coastal population recent decades makes it likely hurricane-spawned destruction in coming years will occur on a scale many times greater than what has been seen in the past.

The team does not attribute recent and projected Atlantic hurricane increases to human-induced global warming.

Gray has been forecasting Atlantic basin storms for more than 18 years. His current research colleagues include Chris Landsea, John Sheaffer, Eric Blake and Philip Klotzbach.

“We have always believed that the atmosphere will act in the future as it has in the past,” Gray said. “This assumption can fail in some years but when applied over a period of several years we find that the atmosphere and ocean does indeed have a long period memory in most years.”

Gray and his team will issue 2002 season updated forecasts in early April and on May 31, to coincide with the official start of the hurricane season on June 1, and August 7. These later, updated forecasts are expected to be more reliable.

Topics Catastrophe USA Natural Disasters Hurricane