Terminology Used During the Hurricane Season (ContributorNetwork)

As the hurricane season makes its grand opening in June, all eyes turn to the Gulf of Mexico and Atlantic Ocean to see just what the is in store for coastal residents this year. The National Hurricane Center released its annual outlook for the Atlantic hurricane season, and information is the most important tool anyone can use to survive through a disaster. This terminology guide for the Hurricane Season can help make sense of the watches, warnings and advisories. The full National Hurricane Center glossary can be found here.

Advisories

The National Hurricane Center (NHC) issues advisories that include all information pertaining to tropical cyclone watches and warnings, as well as the storm's location, intensity and other pertinent information. This is different than other storm advisories which, according to NOAA's glossary, usually identify weather phenomenon that are less severe forms of weather, like flood advisories, but can still cause damage or loss of life if not treated with caution.

Tropical Storm Watch

This is a weather notice that identifies that tropical storm force winds (sustained winds 39 to 73 mph) are possible in a given area within the next 48 hours.

Tropical Storm Warning

This is a weather notice that identifies that tropical storm force winds are expected in a given area over the next 36 hours. It is important to note that the likelihood of the storm occurring in an area with a tropical storm warning is significantly higher than an area with just a tropical storm watch.

Hurricane Watch

This is a weather announcement that identifies that hurricane conditions (sustained winds above 74 mph) are possible at a given location. This notice is issued when it is expected that the tropical storm force winds will reach an area within 48 hours. In theory, a hurricane watch could be issued for an area before a hurricane has officially developed. This would happen if a storm was a tropical storm force, but conditions are right for it to gain strength and make landfall at an area within the 48 hour window.

Hurricane Warning

This is a weather announcement that hurricane conditions are expected in a given area. Again, these notices are going to be issued in advance of the tropical storm force winds reaching the area, usually when those winds are expected within the next 36 hours.

Knots

This is a speed representation of nautical miles per hour. One nautical mile, according to an international agreement detailed by the agency formerly known as the National Bureau of Standards, is equal to approximately 6,076 feet, as opposed to a statute mile which is 5,280 feet. Wind speeds in hurricanes and speed of storm movement are typically reported in knots (kt) and also converted to statute miles per hour (mph).

Tropical Disturbance

This is the beginning of a hurricane. These storms begin showing development and may, or may not, have sustained winds. Their size is usually 100 to 300 nautical miles wide, but are not organized enough to be classed as a tropical depression.

Tropical Depression

A tropical cyclone that has sustained winds of 33kt or less (38 mph or less). Depressions normally represent the first phase of a storm that shows strong development, including a central core that the storm rotates around.

Tropical Storm

A tropical cyclone that has sustained winds between 34kt and 63kt (39 mph and 73 mph). Tropical storms normally are given a name, which stays with the storm until it loses enough energy to return to tropical depression status.

Hurricane

A tropical cyclone that has sustained winds greater than 64kts (74 mph). The term hurricane is used for storms north of the equator and east of the International Date Line and west the Prime Meridian. Pacific tropical cyclones west of the International Date Line are known as typhoons.

Donald is an instructor in military command and control as well as emergency management. He has supported disaster response in a wide range of situations, including hurricanes, forest fires, volcano eruptions and aircraft accidents.

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Understanding Tornado Terminology: What is an EF-5 Tornado? (ContributorNetwork)

With killer tornadoes in half a dozen states in the last month, information about the effective force of each tornado has been thrown around, but few people use the terms properly and fewer still know what they mean.

The Fujita scale was first proposed in 1971 and suggested a rating system for tornadoes and hurricanes based on the wind strength and damage done by the tornado. Since the evaluation of damage cannot begin while the tornado is on the ground, it is improper to discuss a tornado as an F-anything in the midst of the storm.

After a super outbreak of tornadoes around Oklahoma City in 1997, the National Weather Service argued that the wind strength estimates for Fujita scale needed to be revised, resulting in the adoption of the Enhance Fujita Scale, or EF rating of storms.

For clarity, both the largest of the tornadoes to hit Alabama on April 27 and the May 22 tornado in Joplin, Mo., were believed to be EF-4 tornadoes. However, the Severe Storms Center reviews data from the events long after they happen and may change a storms classification based on debris patterns and other information collected over months.

For example, on Nov. 19, 1991, a storm hit Marion, Ill., that was initially classified as a microburst, a sudden downburst of straight-line winds. Six months later, the Storm Prediction Center had reclassified it to an EF-3 tornado.

According to the NWS, the EF scale functions from 0 to 5 and while in theory an F-6 tornado could have been possible under the original Fujita scale, the enhanced scale considers an EF-5 representative of total destruction. Since nothing goes beyond total destruction, a tornado greater than an EF-5 cannot exist.

Based on the EF scale, an EF-0 event represents winds of less than about 75 mph and would damage roofs and tree limbs. An EF-5 tornado would have winds in excess of 261 mph and include total or near total destruction of all types of construction.

Tornado terminology is often used incorrectly, but the most important thing to understand is that the classification will always come after the fact. Until the storm is over, the tornado has no EF rating at all.

Lucinda Gunnin cut her teeth as a reporter covering Illinois government as an intern in the statehouse pressroom. She now brings 20 years experience and insight to covering news.

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