Severe Thunderstorm Watch – Thunderstorms are expected in the area.
Severe Thunderstorm Warning – A thunderstorm is in the area which may produce high winds, hail, dangerous lightning, and/or tornadoes. Take cover immediately.
Tornado Watch – Weather conditions exist in which tornadoes may develop.
Tornado Warning – A tornado has been detected; take shelter immediately.
The Enhanced Fujita Scale uses three-second wind gust estimates for classifying tornados:
EF0 – 65-85 mph wind gust
EF1 – 86-110 mph wind gust
EF2 – 111-135 mph wind gust
EF3 – 136-165 mph wind gust
EF4 – 166-200 mph wind gust
EF5 – over 200 mph
Flash Flood Watch – Flash floods are possible due to high rainfall amounts.
Flash Flood Warning – Flash flooding is occurring. Do not cross flooded areas.
Hurricane Season – The period of June 1 through November 30, during which hurricanes are most likely to develop.
Potential Tropical Cyclone – An undeveloped weather system that can bring tropical storm-force or hurricane-force winds to land areas within 48 hours.
Tropical Depression – Conditions similar to tropical storms but with sustained winds less than 39 mph.
Tropical Storm – Similar to a hurricane but with sustained winds ranging from 39 to 73 mph.
Tropical Storm Watch – Tropical storm conditions are possible within 48 hours.
Tropical Storm Warning – Tropical storm conditions are expected within 36 hours.
Hurricane – A severe cyclonic storm, sometimes 500 miles across, with sustained winds exceeding 73 mph.
Hurricane Watch – A hurricane is advancing, and conditions are favorable for a hurricane to strike within 48 hours.
Hurricane Warning – A hurricane is expected to reach a specified area. It is issued 36 hours before tropical storm force winds are expected to arrive.
Saffir-Simpson Hurricane Wind Scale based on sustained wind speed
Category 1 – 74-95 mph winds; very dangerous winds will produce some damage.
Category 2 – 96-110 mph winds; extremely dangerous winds will cause extensive damage.
Category 3 – 111-129 mph winds; devastating damage will occur.
Category 4 – 130-156 mph winds; catastrophic damage will occur.
Category 5 – 157 mph winds; catastrophic damage will occur making most of the area uninhabitable for weeks or months.
Storm Surge – The abnormal rise of coastal water caused by a hurricane. The cause of most deaths during a hurricane. A watch is issued up to 48 hours before; a warning 36 hours before.
Storm Tide – The coastal water level rise during a storm. It is the combination of storm surge and the normal astronomical tide.
Storm Surge Watch – Life-threatening rising coastal water is possible within 48 hours.
Storm Surge Warning – Inundation from life-threatening rising coastal water will occur within 36 hours.
High Wind Warning – Sustained winds of at least 40 mph lasting at least one hour are imminent.
Gale Warning – Wind speeds of 39-54 mph expected.
Extreme Wind Warning – Extreme sustained winds of 115 mph or greater are expected within the hour. This is usually associated with the eyewall of a hurricane. Take shelter in the interior of a sturdy structure.
Freezing Rain or Drizzle – Expected rain is likely to freeze as soon as it strikes the ground putting a coating of ice, or glaze, on roads and all exposed surfaces.
Ice Storm – A substantial layer of ice is expected to accumulate from freezing rain.
Blizzard – Winds of 35 mph or higher with snow and blowing snow which reduce visibility to less than 1/4 mile for 3 hours or more.
Snow Squalls – Brief, intense snow fall accompanied by strong, gusty winds.
Heavy Snow Warning – A snowfall of four inches or more is expected in a 12-hour period, or a fall of six inches or more is expected in a 24-hour period. Variations of these rules may be used in different parts of the country depending on what the normal snowfall is.
Winter Weather Alerts – Issued by the local National Weather Service office based on local criteria. These are issued for winter weather, freezing rain, blizzards, winter storms, wind chill, lake-effect snow, and snow squalls. Advisories mean Be Aware. Watches mean Be Prepared. Warnings mean Take Action!
Heat Advisory – Dangerously high temperatures are expected in 1 to 3 days.
Excessive Heat Watch – Unusually hot temperatures, possibly combined with high humidity, are expected in 2 to 5 days, and will last at least 2 days.
Excessive Heat Warning – Extremely dangerous heat conditions will occur in 1 to 3 days.
Tsunami Watch – A distant earthquake has occurred, and a tsunami is possible.
Tsunami Advisory – A tsunami with potentially strong currents or dangerous waves is expected or occurring. Stay out of the water and away from the beach.
Tsunami Warning – A tsunami may cause widespread, dangerous, coastal flooding and may continue for an extended period. Evacuation is recommended.
Fire Weather Watch – Critical fire weather conditions are possible in the next 18 to 96 hours. It may also be issued for the next 12 hours in cases of dry lightning.
Red Flag Warning – Critical fire weather conditions are ongoing or expected within the next 12 to 48 hours.