The NWS divides severe weather alerts into several types of hazardous/hydrologic events:

Alert Type

Description
Aviation Aviation hazards
Coastal/lakeshore hazards Hydrological hazards that may affect property, marine or leisure activities in areas near ocean and lake waters including high surf and coastal or lakeshore flooding, as well as rip currents.
Fire weather Weather conditions that contribute to an increased risk and help cause the spread of wildfires.
Flooding Hazardous hydrological events resulting in temporary inundation of land areas not normally covered by water, often caused by excessive rainfall.
Marine hazards Hazardous events that may affect marine travel, fishing and shipping interests along large bodies of water, including hazardous seas and freezing spray.
Non-precipitation hazards Weather hazards not directly associated with any of the above including extreme heat or cold, dense fog, high winds, and river or lakeshore flooding.
Other Hazards Other Hazards
Severe local storms Short-fused, small-scale hazardous weather or hydrologic events produced by thunderstorms (including large hail, damaging winds, tornadoes, and flash floods).
Temperature Temperature
Tropical cyclone hazards Hazardous tropical cyclone events that may affect property in inland areas or marine activities in coastal waters, resulting in wind damage, storm surge, tornadoes and flooding rain.
Windchill Windchill
Winter storms Weather hazards associated with freezing or frozen precipitation (freezing rain, sleet, and/or snow), or combined effects of winter precipitation and strong winds.