Tropical System Classification

Tropical Depression

Tropical Storm

Hurricane

Beaufort Scale for Hurricanes

Category One Hurricane

Central Pressure

Wind Speeds

Possible Storm Surge

Damage Possible

Category Two Hurricane

Central Pressure

Wind Speeds

Possible Storm Surge

Damage Possible

MODERATE:

Considerable damage is done to shrubbery and tree foliage, some trees are blown down.

Major structural damage occurs to exposed mobile homes. Extensive damage occurs to poorly constructed signs.

Some damage is done to roofing materials, windows, and doors; no major damage occurs to the building integrity of structures.

Coastal roads and low-lying escape routes inland may be cut by rising water 2-4 hours before the hurricane center arrives.

Considerable pier damage occurs, marinas are flooded.

Small craft in unprotected anchorages torn from moorings.

Evacuation of some shoreline residences and low-lying island areas is required.

Category Three Hurricane

Central Pressure

Wind Speeds

Possible Storm Surge

945 - 964 mb
27.91 - 28.47 in

111 - 130 MPH
96 - 113 KTS

9 - 12 ft
2.7 - 3.7 m

Damage Possible

EXTENSIVE:

Foliage torn from trees and shrubbery; large trees blown down.

Practically all poorly constructed signs are blown down.

Some damage to roofing materials of buildings occurs, with some window and door damage.

Some structural damage occurs to small buildings, residences and utility buildings.

Mobile homes are destroyed. There is a minor amount of failure of curtain walls (in framed buildings).

Serious flooding occurs at the coast with many smaller structures near the coast destroyed.

Larger structures near the coast are damaged by battering waves and floating debris.

Low-lying escape routes inland may be cut by rising water 3-5 hours before the hurricane center arrives.

Flat terrain 5 feet (1.5 m) or less above sea level flooded inland 8 miles (13 km) or more.

Evacuation of low-lying residences within several blocks of shoreline may be required.

Category Four Hurricane

Central Pressure

Wind Speeds

Possible Storm Surge

920-944 mb
27.17-27.88 in

131 - 155 MPH
114 - 135 KTS

13 - 18 ft
3.9 - 5.5 m

Damage Possible

EXTREME:

Shrubs and trees are blown down; all signs are down.

Extensive roofing material and window and door damage occurs.

Complete failure of roofs on many small residences occurs.

There is complete destruction of mobile homes.

Some curtain walls experience failure.

Flat terrain 10 feet (3 m) or less above sea level flooded inland as far as 6 miles (9.7 km).

Major damage to lower floors of structures near the shore due to flooding and battering by waves and floating debris.

Low-lying escape routes inland may be cut by rising water 3-5 hours before the hurricane center arrives.

Major erosion of beaches occurs.

Massive evacuation of all residences within 500 yards (457 m) of the shoreline may be required, and of single-story residences on low ground within 2 miles (3.2 km) of the shoreline.

Category Five Hurricane

Central Pressure

Wind Speeds

Possible Storm Surge

< 920 mb
< 27.17 in

> 155 MPH
> 135 KTS

> 18 ft
> 5.5 m

Damage Possible

CATASTROPHIC:

Shrubs and trees are blown down; all signs are down.

Considerable damage to roofs of buildings.

Very severe and extensive window and door damage occurs.

Complete failure of roof structures occurs on many residences and industrial buildings, and extensive shattering of glass in windows and doors occurs.

Some complete buildings fail.

Small buildings are overturned or blown away.

Complete destruction of mobile homes occurs.

Major damage occurs to lower floors of all structures located less than 15 ft (4.6 m) above sea level and within 500 yards (457 m) of the shoreline.

Low-lying escape routes inland are cut by rising water 3-5 hours before the hurricane center arrives.

Major erosion of beaches occurs.

Massive evacuation of residential areas on low ground within 5 to 10 miles (8-16 km) of the shoreline may be required.

Damage Possible

Automobile sized missiles fly through the air in excess of 100 meters

Trees debarked

Steel re-enforced concrete structures badly damaged