Marine Glossary

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storm

1. Wind of force 10 (48 to 55 knots) on the Beaufort scale. See also violent storm.

Storm warnings are issued for present or expected sustained winds greater than 48 knots. See G314. Such a warning system was initiated by Robert FitzRoy in England in the mid 1800s. See related warnings under small craft advisory.

2. Any disturbed state of the atmosphere, especially as affecting the earth's surface, and strongly implying destructive or otherwise unpleasant weather. In synoptic meteorology, a storm is a complete individual disturbance identified on synoptic charts as a complex of pressure, wind, clouds, precipitation, etc., or identified by such means as radar.

Thus, storms range in scale from tornadoes and thunderstorms, through tropical cyclones, to widespread extra-tropical cyclones. From a local and special interest viewpoint, a storm is a transient occurrence identified by its most destructive or spectacular aspect. Examples are rain storms, wind storms, hail storms, snow storms, etc., Notable special cases are blizzards, ice storms, sandstorms, and dust storms.

3. A term once used by seamen for what is now called violent storm on the Beaufort wind scale.

Note that outside of the tropics we use storm force winds of 48 to 63 kts, but in the tropics they use tropical storm force winds that are 34 to 63 kts.