Recent Comments

Hurricane Categories

The Saffir-Simpson Hurricane Scale is a 1-5 rating based on the hurricane’s present intensity. This is used to give an estimate of the potential property damage and flooding expected along the coast from a hurricane landfall. Wind speed is the determining factor in the scale, as storm surge values are highly dependent on the slope of the continental shelf in the landfall region. Note that all winds are using the U.S. 1-minute average.

CATEGORY ONE HURRICANE: Winds 74-95 mph (64-82 kt or 119-153 kph). Storm surge generally 4-5 feet above normal. No real damage to building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Some damage to poorly constructed signs. Also, some coastal road flooding and minor pier damage. Hurricanes Allison of 1995 and Danny of 1997 were Category One hurricanes at peak intensity.

CATEGORY TWO HURRICANE: Winds 96-110 mph (83-95 kt or 154-177 kph). Storm surge generally 6-8 feet above normal. Some roofing material, door, and window damage of buildings. Considerable damage to shrubbery and trees with some trees blown down. Considerable damage to mobile homes, poorly constructed signs, and piers. Coastal and low-lying escape routes flood 2-4 hours before arrival of the hurricane center. Small craft in unprotected anchorages break moorings. Hurricane Bonnie of 1998 was a Category Two hurricane when it hit the North Carolina coast, while Hurricane Georges of 1998 was a Category Two Hurricane when it hit the Florida Keys and the Mississippi Gulf Coast.

CATEGORY THREE HURRICANE: Winds 111-130 mph (96-113 kt or 178-209 kph). Storm surge generally 9-12 feet above normal. Some structural damage to small residences and utility buildings with a minor amount of curtainwall failures. Damage to shrubbery and trees with foliage blown off trees and large tress blown down. Mobile homes and poorly constructed signs are destroyed. Low-lying escape routes are cut by rising water 3-5 hours before arrival of the hurricane center. Flooding near the coast destroys smaller structures with larger structures damaged by battering of floating debris. Terrain continuously lower than 5 feet above mean sea level may be flooded inland 8 miles (13 km) or more. Evacuation of low-lying residences with several blocks of the shoreline may be required. Hurricanes Roxanne of 1995 and Fran of 1996 were Category Three hurricanes at landfall on the Yucatan Peninsula of Mexico and in North Carolina, respectively.

CATEGORY FOUR HURRICANE: Winds 131-155 mph (114-135 kt or 210-249 kph). Storm surge generally 13-18 feet above normal. More extensive curtainwall failures with some complete roof structure failures on small residences. Shrubs, trees, and all signs are blown down. Complete destruction of mobile homes. Extensive damage to doors and windows. Low-lying escape routes may be cut by rising water 3-5 hours before arrival of the hurricane center. Major damage to lower floors of structures near the shore. Terrain lower than 10 ft above sea level may be flooded requiring massive evacuation of residential areas as far inland as 6 miles (10 km). Hurricane Luis of 1995 was a Category Four hurricane while moving over the Leeward Islands. Hurricanes Felix and Opal of 1995 also reached Category Four status at peak intensity.

CATEGORY FIVE HURRICANE: Winds greater than 155 mph (135 kt or 249 kph). Storm surge generally greater than 18 feet above normal. Complete roof failure on many residences and industrial buildings. Some complete building failures with small utility buildings blown over or away. All shrubs, trees, and signs blown down. Complete destruction of mobile homes. Severe and extensive window and door damage. Low-lying escape routes are cut by rising water 3-5 hours before arrival of the hurricane center. Major damage to lower floors of all structures located less than 15 feet above sea level and within 500 yards of the shoreline. Massive evacuation of residential areas on low ground within 5-10 miles (8-16 km) of the shoreline may be required. Hurricane Mitch of 1998 was a Category Five hurricane at peak intensity over the western Caribbean. Hurricane Gilbert of 1988 was a Category Five hurricane at peak intensity and is the strongest Atlantic tropical cyclone of record.

Quoted from the National Hurricane Center , Tropical Prediction Center. 

All hurricanes are dangerous, but some are more so than others. The way storm surge, wind, and other factors combine determines the hurricane’s destructive power. To make comparisons easier, and to make the predicted hazards of approaching hurricanes clearer, NOAA’s hurricane forecasters use a disaster-potential scale, which assigns storms to five categories. Category 1 is a minimum hurricane and category 5 is the worst case. The criteria for each category are shown below.

GORY   (milli-   (inches)       (mph)      (ft)   DAMAGE    STORM

1      980 or    less than      74-95      4-5    minimal   Agnes 1972, Ismael 1995, 
       greater   or = 28.94                                 Danny 1997, Gaston 2004, 
                                                            Stan 2005

2      965-979   28.50-28.91    96-110     6-8    moderate  Kate 1965, Fifi 1974, 
                                                            Diana 1990, Erin 1995,
                                                            Juan 2003, Wilma 2005

3      945-964   27.91-28.47    111-130    9-12   extensive Elena 1985, Alicia 1983
                                                            Roxanne 1995, Fran 1996,
                                                            Isidore 2002, Jeanne 2004

4      920-944   27.17-27.88    131-155    13-18  extreme   "Galveston" 1990, 
                                                            Hazel 1954, Iniki 1992, 
                                                            Hugo 1989, Iris 2001,
                                                            Charley 2004

5      less        less          more      more   cata-     "LABOR DAY
       than        than          than      than   strophic  STORM" 1935, Luis 1995,
       920         27.17         155       18               Gilbert 1988, Andrew 1992

Leave a Reply