Inside WRAL

Nate's fascinating hurricane facts

Posted June 1, 2012
Updated June 3, 2012

Did you know that hurricanes should always be referred to as "it" and never "he" or "she," even if it has a masculine or feminine name?

That's just one of the fascinating facts WRAL meteorologist Nate Johnson shared with our newsroom today to mark the official start of the Atlantic hurricane season. Here are some more interesting facts from Nate:

Hurricane Season

Hurricane season in the Atlantic basin runs from June 1 through Nov. 30; however, as Alberto and Beryl reminded us this year, tropical storms and hurricanes can and do, from time to time, form outside of this time period. The Atlantic hurricane season usually peaks in late August through September. There are different hurricane seasons for the Pacific and other oceans/basins. (In other words, the June 1 - Nov. 30 dates only apply to Atlantic storms, nowhere else.)

Names (and pronunciations)

The names are from lists that get recycled every six years, unless a storm is particularly deadly or damaging, in which case the name is retired and replaced (e.g. Irene from last year has been retired going forward). The actual names are a blend of names from English, French and Spanish – languages from the cultures represented by the areas affected by Atlantic storms – and often have pronunciations that differ significantly from what their English spelling would suggest.

2012 names

Alberto – al-BAIR-toe
Beryl – BER-ril
Chris – kris
Debby – DEH-bee
Ernesto – er-NES-toh
Florence – FLOOR-ence
Gordon – GOR-duhn
Helene – heh-LEEN
Isaac – EYE-zik
Joyce – joyss
Kirk – kurk
Leslie – LEHZ-lee
Michael – MY-kuhl
Nadine – nay-DEEN
Oscar – AHS-kur
Patty – PAT-ee
Rafael – rah-fah-ELL
Sandy – SAN-dee
Tony – TOH-nee
Valerie – VAH-lur-ee
William – WILL-yum

If more names are needed, storms will be named using letters from the Greek alphabet. After William, the next storm would be named "Alpha," then "Beta," and so on. Let's hope we don't run out of those!

Historic NC Hurricanes

Irene - 2011
Isabel - 2003
Floyd - 1999
Fran - 1996
Hugo - 1989
Gloria - 1985
Diana - 1984
Donna - 1960
Ione - 1955
Hazel - 1954

Hurricane Intensity Scale

Hurricanes are categorized by their wind speeds on the Saffir-Simpson Hurricane Wind Scale:

Category One: 74 – 95 mph
Category Two: 96 – 110 mph
Category Three: 111 – 129 mph
Category Four: 130 – 156 mph
Category Five: 157+ mph

Storms that reach Category Three status (that is, winds of at least 111 mph), are considered "major" hurricanes. Winds are only part of the story, and usually not the most important part, either: Landfalling hurricanes also bring with them a storm surge of high water, as well as torrentially heavy, flooding rainfall and the threat for tornadoes. Flooding is what kills most people in tropical systems, not wind.

Watches, Warnings, Advisories, etc.

As a tropical system approaches land — or is forecast to develop near land — any number of advisories may be issued. Where they are posted is a function of both the forecast track, size, and intensity of the storm as well as the uncertainty involved with that forecast.

  • Tropical Storm Watch — An announcement that tropical storm conditions (sustained winds of 39 to 73 mph) are possible within the specified coastal area within 48 hours.
  • Tropical Storm Warning — An announcement that tropical storm conditions (sustained winds of 39 to 73 mph) are expected within the specified coastal area within 36 hours.
  • Hurricane Watch — An announcement that hurricane conditions (sustained winds of 74 mph or higher) are possible somewhere within the specified coastal area. Because hurricane preparedness activities become difficult once winds reach tropical storm force, the hurricane watch is issued 48 hours in advance of the anticipated onset of tropical-storm-force winds.
  • Hurricane Warning — An announcement that hurricane conditions (sustained winds of 74 mph or higher) are expected somewhere within the specified coastal area. Because hurricane preparedness activities become difficult once winds reach tropical storm force, the hurricane warning is issued 36 hours in advance of the anticipated onset of tropical-storm-force winds.

Hurricane Life Cycle

Most hurricanes will begin as a tropical disturbance, which is usually nothing more than a cluster of thunderstorms out in the tropics. Once this storm cluster begins to show signs of organization (i.e. a closed counter-clockwise circulation at the surface), it will be classified as a tropical depression and given a number in sequence. The numbers do not repeat in a given year.

As the storm continues to strengthen, this circulation will strengthen, increasing the wind speeds. Once the system has a closed circulation and winds of at least 39 mph, it will be promoted to tropical storm and given a name. A strengthening tropical storm will graduate to hurricane status once it has winds of at least 74 mph.

At some point, the storm may make landfall (where the eye comes ashore) or brush the coast (where the coast is affected but the center of the storm doesn't come on shore). After the storm moves on shore or over colder waters, it usually weakens rapidly, and at some point, may "transition" to become an extratropical cyclone (also called a post-tropical cyclone, which is a fancy name for a more "traditional" low pressure with a cold front and warm front) or a remnant low, which can often be extremely prolific rain producers even days or weeks after the storm makes landfall.

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