Departments

Terms to Know

waterspoutWaterspout Tornadic waterspouts are tornadoes that form over water, or move from land to water. They have the same characteristics as a land tornado. They are associated with severe thunderstorms, and are often accompanied by high winds and seas, large hail, and frequent dangerous lightning.

Fair weather waterspouts usually form along the dark flat base of a line of developing cumulus clouds. This type of waterspout is generally not associated with thunderstorms. While tornadic waterspouts develop downward in a thunderstorm, a fair weather waterspout develops on the surface of the water and works its way upward. By the time the funnel is visible, a fair weather waterspout is near maturity. Fair weather waterspouts form in light wind conditions so they normally move very little.

If a waterspout moves onshore, the National Weather Service issues a tornado warning, as some of them can cause significant damage and injuries to people. Typically, fair weather waterspouts dissipate rapidly when they make landfall, and rarely penetrate far inland.



superstormTropical Wave A cluster of clouds and/or thunderstorms with little or no circulation or strong wind.

Tropical Depression An organized system of clouds and thunderstorms with a defined surface circulation and maximum sustained winds of 38 MPH (33 knots) or less. Sustained winds are defined as one-minute average wind measured at about 33 ft (ten meters) above the surface.

Tropical Storm  An organized system of strong thunderstorms with a defined surface circulation and maximum 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.

Storm Surge A dome of water pushed onshore by hurricane and tropical storm winds. Storm surges can reach 25 feet high and be 50–1000 miles wide.

Storm Tide A combination of storm surge and the normal tide (i.e., a 15-foot storm surge combined with a two foot normal high tide over the mean sea level created a 17-foot storm tide).

Hurricane season The part of the year having a relatively high incidence of hurricanes. The hurricane season in the Atlantic, Caribbean and Gulf of Mexico runs from June first to November 30. The season in the Eastern Pacific basin runs from May 15 to November 30. The season in the Central Pacific basin runs from June first to November 30.

Hurricane/Tropical Storm Watch Issued when hurricane/tropical storm conditions are possible in the specified area, usually within 36 hours. Tune in to NOAA Weather Radio, commercial radio, or television for information.

Hurricane/Tropical Storm Warning Issued when hurricane/tropical storm conditions are expected in the specified area, usually within 24 hours.

Short Term Watches and Warnings These warnings provide detailed information about specific hurricane threats, such as flash floods and tornadoes.

Eye The roughly circular area of comparatively light winds that encompasses the center of a severe tropical cyclone. The eye is either completely or partially (at least 50 percent) surrounded by the eye-wall cloud, an organized band or ring of cumulonimbus clouds.

Eye Wall A ring of cumulonimbus clouds that swirl around the eye where the heaviest precipitation and strongest winds are found.

Spiral Rainbands Bands of heavy convective showers that spiral inward toward the storm's center.