Wednesday, June 05, 2013

Hurricanes: Frequently Asked Questions

Hurricane season officially started last Saturday. The National Hurricane Center updated their hurricane season forecast. It continues to highlight above average activity. One lone storm could develop further this weekend.

This usually brings up many of the same questions about hurricanes and hurricane season. Rather than answer each question as they are received, here is a substantial list of questions that I've received over the years WITH answers with some help from NOAA's hurricane FAQ page.

If you have a question that's not listed here, feel free to send me an EMAIL, TWEET OR FACEBOOK MESSAGE

QUESTION #1: When it rains inside a hurricane, is it salt water?

No. When the water evaporates from the ocean, it leaves behind the salt.

QUESTION #2: Who names tropical storms? When did they start naming them?

In 1945, the military started naming Pacific storms with women's names. From 1950 to 1952, tropical cyclones of the North Atlantic Ocean were identified by the phonetic alphabet (Able-Baker-Charlie...). But in 1953 the US Weather Bureau switched to women's names solely. In 1979, the World Meteorological Organization began naming storms using a list that alternates between men's and women's names.

QUESTION #3: What happens when they run out of names in a specific year?

The Greek alphabet will be used (alpha, beta, gamma, delta...etc)  This happened in 2005 when we went 7 names deep into the Greek alphabet. That storm was named 'Zeta".

QUESTION #4: What names have been retired?

Here is the list: Audrey 1957, Agnes 1972, Anita 1977, Allen 1980, Alicia 1983, Andrew 1992, Allison 2001, Betsy 1965, Beulah 1967, Bob 1991, Connie 1955 ,Carla 1961, Cleo 1964, Carol 1965, Camille 1969, Celia 1970, Carmen 1974, Cesar 1996, Charley 2004, Diane 1955, Donna 1960, Dora 1964, David 1979, Diana 1990, Dennis 2005, Dean 2007, Edna 1968, Eloise 1975, Elena 1985, Flora 1963, Fifi 1974, Frederic 1979, Fran 1996, Floyd 1999, Fabian 2003, Frances 2004, Felix 2007, Gracie 1959, Gloria 1985, Gilbert 1988, Georges 1998, Gustav 2008
Hazel 1954, Hattie 1961, Hilda 1964, Hugo 1989,Hortense 1996, Ione 1955, Inez 1966, Iris 2001, Isidore 2002, Isabel 2003, Ivan 2004, Ike 2008,Igor 2010, Irene 2011, Janet 1955, Joan 1988, Juan 2003, Jeanne 2004, Klaus 1990, Keith 2000, Katrina 2005, Luis 1995, Lenny 1999, Lili 2002, Marilyn 1995, Mitch 1998, Michelle 2001, Noel 2007, Opal 1995, Paloma 2008, Roxanne 1995, Rita 2005, Stan 2005, Tomas 2010, Wilma 2005

QUESTION #5:  What happens if a storm cross from the Atlantic to Pacific or Pacific to it renamed?

If the storm remains a tropical cyclone as it moves across Central America (Atlantic to Pacific or vise versa) then it will keep the original name. Only if the tropical cyclone dissipates with just a tropical disturbance remaining, will the NHC give the system a new name assuming it becomes a tropical cyclone once again.
QUESTION #6: Why can't we use a nuclear bomb to dissipate the hurricane?

NOAA has a detailed explanation: "A fully developed hurricane can release heat energy at a rate of 5 to 20x10^13 watts". This is equivalent to 200 times the world-wide electrical generating capacity!..."

That is the energy created from the condensation of water vapor molecules into water droplets. When you consider that 1/2" of rainfall per day over a 360 mile radius from the center, you can understand the power generation of a hurricane. NOAA continues...

"...This is equivalent to the heat release is equivalent to a 10-megaton nuclear bomb exploding every 20 minutes! In addition, an explosive, even a nuclear explosive, produces a shock wave, or pulse of high pressure, that propagates away from the site of the explosion somewhat faster than the speed of sound. Such an event doesn't raise the barometric pressure after the shock has passed because barometric pressure in the atmosphere reflects the weight of the air above the ground. For normal atmospheric pressure, there are about ten metric tons (1000 kilograms per ton) of air bearing down on each square meter of surface. In the strongest hurricanes there are nine. To change a Category 5 hurricane into a Category 2 hurricane you would have to add about a half ton of air for each square meter inside the eye, or a total of a bit more than half a billion (500,000,000) tons for a 20 km radius eye. It's difficult to envision a practical way of moving that much air around."  

Basically, it can't be done!


What is the fastest a storm intensified?

Hurricane Wilma in 2005 went from 954 mb to 901 mb in a 5 hour 23 minute period for a 9.8 mb/hr pressure drop. The winds went from 150 mph to 184 mph in 5 in that period.
What was the lowest hurricane pressure ever recorded?

Typhoon Tip in the Northwest Pacific Ocean on 12 October 1979 was measured to have a central pressure of 870 mb.
Hurricane Wilma's 882 mb lowest pressure (estimated from a dropsonde) in 2005 is the most intense for the Atlantic basin.

What was the strongest wind ever recorded in a tropical cyclone?

Tropical Cyclone Olivia off the coast of Australia on April 10, 1996 sets the new world record for the Highest surface wind speed with a gust at 253.5 mph
Typhoon Nancy on 12 September, 1961 located in the Northwest Pacific region has estimated maximum sustained winds of 213 mph.
Hurricane Camille (1969) and Hurricane Allen (1980) have had winds that are estimated to be 190 mph.

What was the largest hurricane?

Typhoon Tip had gale force winds (39 mph) which extended out for 675 miles from the radius in the Northwest Pacific on 12 October, 1979,  It was half the size of the continental United States!

What tropical storm lasted the longest?

What has been the deadliest hurricanes for the US?

A great list created by Chris Landsea at NOAA

What is the total number of storms through 2012?

Why doesn't the South Atlantic Ocean experience tropical cyclones?

It has happened. Once in 2004 off of the coast of Brazil. The other was a disturbance off the coast of Africa in April of 1991. The region south of the equator has no convergence zone that promotes "spin" for thunderstorm development necessary for large scale tropical systems. The wind sheer is much too great.

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