October, Not All Over!

by Don Street

There is an old Caribbean rhyme regarding hurricanes:

June, too soon
July, stand by
September, remember
October, all over

But the last line is no longer true.
Sailors in the Caribbean complained bitterly in the late 1990s when insurance companies changed their closing date of hurricane season from October 30th to November 30th. The figures that follow show that the change is completely justifiable. There were more November and December hurricanes in the last ten years than there had been in the previous 50.

In 1980 I obtained a book from the US National Oceanographic and Atmospheric Administration (NOAA) that showed the track charts of every hurricane from 1879 to around the mid-1970s. I then regularly obtained loose-page updates until 1988 when a new book came out that tracked all hurricanes from 1851 until then. I have since updated with loose pages right up through 2020.
I have just done another review, as mentioned in last month’s Readers’ Forum, and have come up come up with some interesting figures on November and December hurricanes from 1950 to 2020.
In the months of November from 1950 to 1980 there were eight hurricanes and four tropical storms, and the period from 1980 to 1989 saw four November hurricanes in nine years. Ten November hurricanes and nine tropical storms occurred in the 30 years from 1990 to 2020.
However, with few exceptions, these November hurricanes had little or no effect on the islands of the Eastern Caribbean. The November hurricanes were either in the Western Caribbean or Gulf of Mexico, or out in the Atlantic.

One notable exception was Hurricane Klaus. In early November 1984 Klaus formed south of Puerto Rico, headed northeast hitting the US and British Virgin Islands, and continued eastward passing north of St. Martin.
Another remarkable exception was 1999’s famous “Wrong Way Lenny.” Hurricane Lenny was the fourth strongest November hurricane on record, behind the 1932 Cuba hurricane and 2020’s Hurricanes Iota and Eta. Lenny formed on November 13th in the western Caribbean and maintained a west-to-east track for its entire duration. It attained hurricane status south of Jamaica on November 15th and passed south of Hispaniola and Puerto Rico over the next few days. Lenny rapidly intensified over the northeastern Caribbean on November 17th, attaining peak winds of 134 knots about 21 miles south of St. Croix. It gradually weakened while moving through the Leeward Islands, eventually dissipating on November 23rd over the open Atlantic. Lenny’s storm surges affected the entire Eastern Caribbean chain.

December storms can be even more surprising.
Hurricane Alice formed on December 30th 1954 west of Grenada, headed northwest, took a right-angle turn passing over St. Kitts & Nevis, and then carried on out to sea. There was a December tropical storm in 1953, giving one December hurricane and one December tropical storm between 1950 and 2000. Then there were two December tropical storms in 2003, two in 2005, one in 2007 and one in 2013 — six in ten years.

Going through the yearly track charts it is obvious that in the months of September and October, the northern Lesser Antilles are hit by hurricanes to the point that area from Anguilla to Puerto Rico is referred to as “Hurricane Alley.” But it’s also apparent that the next couple of months aren’t risk free.
The US National Hurricane Center (NHC) has stated that 2021 will be an active hurricane season, so stay alert. Regularly check www.nhc.noaa/gov for information on systems that may form tropical storms or hurricanes, and note their positions, course and speed of advance.

The vast majority of hurricanes that affect the islands of Eastern Caribbean start as low-pressure areas of rain southeast of the Cape Verde Islands. These move westwards into the Atlantic and sometimes pick up a circular motion. If and when one does, the NHC notes it as a tropical depression and gives its position, speed of advance, and direction. The depression sometimes forms into a tropical storm and then sometimes into a hurricane. These systems, as long as they are below 19°N, progress westwards, rarely changing course more than five degrees in 24 hours. With very few exceptions the alteration of course is to the north. Very seldom has a course alteration lasted more than 48 hours before the system again turns west. Only twice since 1851 has a jog to the south lasted more than 48 hours, and those two cases lasted 72 hours then turned west again.

Most tropical storms or hurricanes when they arrive at the island chain are relatively small in diameter although they may be very intense. Once a hurricane passes through the islands it can do anything, even make a right angle turn to the north, which has happened twice since 1851. Once in the Caribbean, alterations of course are to the north, never to the south. And after a hurricane passes north of 19°N it can go anywhere. If it continues on to the warm water of the Bahamas it usually builds up a big head of steam and becomes a major hurricane, causing havoc in the Bahamas and in the States.
It may be October, but it’s not time to let your guard down yet.

For more information on hurricanes visit Don’s website at www.street-iolare.com

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