StormGlobe — glossary
Plain-language definitions of the terms used across StormGlobe (NOAA NHC).
Storm types & strength
- Tropical depression
- An organized tropical system with maximum sustained winds up to 38 mph (62 km/h). Not yet named.
- Tropical storm
- A tropical cyclone with sustained winds of 39–73 mph (63–118 km/h); strong enough to be given a name.
- Hurricane / typhoon / cyclone
- A tropical cyclone with sustained winds of at least 74 mph (119 km/h). Called a hurricane in the Atlantic and NE Pacific, typhoon in the NW Pacific, cyclone in the Indian Ocean and South Pacific.
- Major hurricane
- A hurricane of Category 3 or higher (winds ≥111 mph / 178 km/h) on the Saffir–Simpson scale.
- Rapid intensification
- An increase in sustained winds of at least 35 mph (30 kt) within 24 hours — dangerous and hard to forecast.
Forecast products
- Saffir–Simpson scale
- A 1–5 rating of a hurricane by maximum sustained wind. It rates wind damage only — not storm surge or rainfall.
- Forecast track
- The predicted path of the storm’s center over the coming days.
- Cone of uncertainty
- The area the storm center is likely to stay within (about 2/3 of the time). It shows the center’s probable path, not the storm’s size or its hazards.
- Watch vs. warning
- A watch means tropical-storm/hurricane conditions are possible (typically within 48 h); a warning means they are expected (within 36 h) — act now.
Hazards
- Storm surge
- Seawater pushed ashore by a storm’s winds, raising water levels far above normal tide. Historically the deadliest hurricane hazard.
- Eye / eyewall
- The calm center (eye) ringed by the eyewall, the band of strongest winds and heaviest rain. Calm in the eye is temporary — the eyewall returns.
- Rainbands
- Spiral bands of showers and thunderstorms around the center that bring heavy rain and can spawn tornadoes far from the eye.
Intensity scale (kt)
- Tropical Depression
- 0 kt
- Tropical Storm
- 34 kt
- Category 1
- 64 kt
- Category 2
- 83 kt
- Category 3
- 96 kt
- Category 4
- 113 kt
- Category 5
- 137 kt