HURRICANE
CLASSIFICATIONS

These are some of the terms most commonly used by the National Weather Service when referring to hurricanes.

Tropical Disturbance - A moving area of thunderstorms in the tropics with a poorly organized rotary circulation.

Tropical Depression - An area of low pressure, organized rotary circulation of clouds and winds to 38 mph.

Tropical Storm - Well organized counter-clockwise circulation of clouds and winds 39-73 mph. The storm is assigned a name.

Tropical Storm Watch - The possibility of winds between 39-73 mph effecting the area within 24 hours.

Tropical Storm Warning - The likeliness of winds between 39-73 mph effecting the area within 24 hours.

Hurricane - When a tropical Storm reaches winds of 74 mph or more, it is classified a hurricane.

Hurricane Watch - A hurricane may threaten your area within 48 hours.

Hurricane Warning - A hurricane is expected to strike your area within 24 hours or less.

Tornado Watch - Tornadoes and severe thunderstorms are expected in your area.

Tornado Warning - Tornado sighted in your area, take shelter.

Storm Surge - The strong winds associated with hurricanes and tropical storms cause the sea level to rise above normal tidal heights, with giant wind-driven waves and strong unpredictable currents, sometimes covering 50 miles.

Advisory - A method for disseminating hurricane and storm data to the public every 6 hours. Small craft warnings are released as necessary.

Special Advisory - Warning given anytime there is a significant change in weather conditions or change in warnings.

Intermediate Advisory - A method for updating regular advisory information every 2 or 3 hours as necessary.

Tropical Cyclone Classification

Tropical Depression 20-34kts Tropical Storm 35-64kts Hurricane 65+kts or 74+mph

Saffir-Simpson Scale for Hurricane Classification
StrengthWind Speed (Kts)Wind Speed (MPH)Pressure (Millibars)Pressure
Category 1>65- 82 kts74- 95 mph>980 mb28.94 "Hg
Category 2>83- 95 kts96-110 mph965-979 mb28.50-28.91 "Hg
Category 3>96-113 kts111-130 mph945-964 mb27.91-28.47 "Hg
Category 4>114-135 kts131-155 mph920-944 mb27.17-27.88 "Hg
Category 5>135 kts>155 mph919 mb27.16 "Hg

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HURRICANE
TRACKING
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