Severe Weather Terms

Confused by tropical terms? Here is a brief glossary containing terms you will hear during weather broadcasts on KALB/NALB and on other media sources.

Cyclone: Refers to a center of low pressure in the atmosphere. The wind swirls into the cyclone from all directions.

Disturbance: An abnormality in the flow of the atmosphere.

Eye: The pressure center of a hurricane.

Eyewall: The organized ring of deep convection surrounding the eye of the hurricane.

Hurricane: A non-frontal tropical cyclone with sustained (1-2 minute average) wind speeds of 74 mph or higher.

Hurricane Warning: An announcement advising the public that hurricane conditions are likely within 36 hours.

Hurricane Watch: An announcement advising the public that hurricane conditions are possible within 48 hours.

Intertropical Convergence Zone (ITCZ): A zone of low pressure near the equator where the trade winds from each hemisphere converge. This pattern creates clouds and precipitation and frequently produces tropical weather systems.

Invest: A weather system in which there is interest in collecting data or running a suite of computer models.

Major Hurricane: Refers to a hurricane that has achieved a rating of 3 or higher on the Saffir-Simpson scale.

Post-Tropical Cyclone: Refers to a former tropical cyclone.

Potential Tropical Cyclone: A new term introduced in 2017 to include disturbances that threaten to become tropical cyclones and affect land within 48 hours.

Saffir-Simpson Scale: A categorization of the potential impact a hurricane may have upon landfall. Rating range from 1 to 5.

Storm Surge: An abnormal rise in sea level that commonly accompanies tropical and extratropical weather systems. The storm surge is estimated by subtracting the astronomic high tide from the observed storm tide.

Storm Tide: The actual water level resulting from the astronomic high tide combined with the storm surge.

Subtropical Cyclone: A non-frontal low pressure system that has characteristics of both a tropical and a non-tropical cyclone.

Tropical Cyclone: A warm-core, non-frontal, large-scale center of low pressure with organized deep convection and a definite, closed circulation.

Tropical Depression: A tropical cyclone in which the maximum sustained surface wind speed is 38 mph or less.

Tropical Storm: A tropical cyclone in which the maximum sustained surface wind speed is between 39 and 73 mph.

Tropical Storm Warning: Announces the likelihood of tropical storm conditions within 48 hours.

Now you've passed Tropical Terms 101! Keep these tropical tidbits handy during hurricane season.