Reality Check: Hurricane Irma Is NOT the Most Powerful Atlantic Hurricane Ever Recorded


By: - Climate DepotSeptember 7, 2017 2:24 PM

Guest post by David Middleton

Hurricane Irma is really bad.  It may be the worst storm to hit the U.S. since 1935… But it is NOT the most powerful Atlantic hurricane ever recorded.  So… Why do they have to lie about this?

Hurricane Irma Is Now The Most Powerful Atlantic Ocean Storm In Recorded History

Fresh off the back of the devastating Hurricane Harvey, the US is preparing for an even more dangerous storm – Hurricane Irma.

With wind speeds of 300 kilometers per hour (185 miles per hour), Irma now ranks as the most powerful hurricane in the Atlantic Ocean. It is the second most powerful in the Atlantic basin, which includes the Atlantic Ocean, Caribbean Sea, and the Gulf of Mexico, behind Hurricane Allen in 1980 that hit the latter two with winds of 305 km/h (190 mph).

[…]

IFL Science!

Does IFL stand for “I FLunked” Science?

Geography 101

The Caribbean Sea and Gulf of Mexico are in the Atlantic Ocean, just as much as the Sargasso Sea is in the Atlantic Ocean.

 

Caribbean Seasuboceanic basin of the western Atlantic Ocean, lying between latitudes 9° and 22° N and longitudes 89° and 60° W. It is approximately 1,063,000 square miles (2,753,000 square km) in extent. To the south it is bounded by the coasts of VenezuelaColombia, and Panama; to the west by Costa RicaNicaraguaHondurasGuatemalaBelize, and the Yucatán Peninsula of Mexico; to the north by the Greater Antilles islands of CubaHispaniolaJamaica, and Puerto Rico; and to the east by the north-south chain of the Lesser Antilles, consisting of the island arc that extends from the Virgin Islands in the northeast to Trinidad, off the Venezuelan coast, in the southeast. Within the boundaries of the Caribbean itself, Jamaica, to the south of Cuba, is the largest of a number of islands.

Britannica

 

Gulf of Mexico

The Gulf of Mexico is a smaller part of the Atlantic Ocean, but it is the ninth largest body of water in the world.

[…]

Deepsea Waters

Describing Irma as the most powerful Atlantic hurricane ever recorded is like calling Ted Williams the all-time American league home run leader because he hit the most home runs at Fenway Park.

Among the 24 most intense Atlantic hurricanes since 1924, Irma is currently tied for second in wind speed.

Maximum Sustained
Storm Year Winds (mph)
Allen 1980 190
“Labor Day” 1935 185
Gilbert 1988 185
Wilma 2005 185
Irma 2017 185
Mitch 1998 180
Rita 2005 180
“Cuba” 1932 175
Janet 1955 175
Camille 1969 175
David 1979 175
Andrew 1992 175
Katrina 2005 175
Dean 2007 175
“Cuba” 1924 165
Isabel 2003 165
Ivan 2004 165
Hattie 1961 160
Hugo 1989 160
“Bahamas” 1929 155
Floyd 1999 155
Igor 2010 155
Opal 1995 150
Gloria 1985 145

Wilma_01

And tied for 12th place according to atmospheric pressure:

Storm Year Minimum Atmospheric 
    Pressure (hPa)
Wilma 2005 882
Gilbert 1988 888
“Labor Day” 1935 892
Rita 2005 895
Allen 1980 899
Camille 1969 900
Katrina 2005 902
Mitch 1998 905
Dean 2007 905
“Cuba” 1924 910
Ivan 2004 910
Irma 2017 913
Janet 1955 914
“Cuba” 1932 915
Isabel 2003 915
Opal 1995 916
Hugo 1989 918
Gloria 1985 919
Hattie 1961 920
Floyd 1999 921
Andrew 1992 922
“Bahamas” 1929 924
David 1979 924
Igor 2010 924

Irma_02

“The Most Powerful Atlantic Ocean Storm In Recorded History” meme fits the narrative: Global warming is causing hurricanes to become more severe… Another lie.

Hurricanes are not increasing in severity

The National Hurricane Center’s hurricane climatology page has a handy list of Atlantic Basin tropical storms, hurricanes and major hurricanes from 1851-2014.  There is no statistically meaningful trend in hurricane frequency or severity.

Irma_05

While there might be a somewhat statistically significant increase in the number of tropical storms (R² = 0.2274), this could simply be due improvements in the detection and identification of storms at sea… There is no statistically meaningful trend in the numbers of hurricanes or major hurricanes.

There are also no statistically meaningful trends in the rates at which tropical storms are “blossoming” into hurricanes or major hurricanes:

Irma_04Irma_03

Records are made to be broken

Irma came very close to breaking a wind speed record.  So what?

The probability, pn(1), that the nth observation of a series xm= x1, x2, … xn has a higher value than the previous observations [pn(1) = Pr(xn > xi |i < n)] can be expressed as:

pn(1)= 1/n

provided the values in series are iid random variables.

(Benestad, 2003)

In 1941, Ted Williams had a .406 batting average.  He was the last major league baseball player to hit over .400.  While each at bat had its own independent probability, if Ted Williams had 5 at bats in a game, he probably had 2 base hits.  While Irma has less than a 1% chance of breaking Allen’s wind speed record, the sum of individual probabilities since 1924 indicate that it’s about time for that record to fall.

Irma_06

Y-axis is the sequential number of new records.

See sheet 1 of the following spreadsheet for expected record calculations:

AtlanticStormTotalsTable (1) 

How did we ever survive the Medieval Warm Period?

If warmer waters inevitably lead to more severe hurricanes… How did humanity survive the Medieval Warm Period?  Or the Minoan Warm Period?  There must have been Category 9 hurricanes every year in 1000 BC!!! (/SARC)

hadsst_s7

Sargasso Sea SST reconstruction  (Keigwin, 1996) and Major New England Hurricanes (Donnelly, 2001).   https://wattsupwiththat.com/2012/11/03/frankenstorm-itis-five-degrees-of-separation-from-reality-and-eleventy-gazillion-joules-under-the-sea/

,