Ed Dunham
Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017)
Reged: Sun
Posts: 2565
Loc: Melbourne, FL
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The Trouble With May
Sat May 26 2007 12:20 PM
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Recently a post made reference to a statement from another site that "No tropical cyclone landfalls are expected along the United States mainland." In my opinion, that statement falls into the categories of irresponsible and/or foolish (and probably others as well). For some of you, this blog will fall into the category of 'things that you really didn't want to know', but at least its based on climatology rather than conjecture.
With the development of Subtropical Storm Andrea earlier this month, I decided to take a look at past seasons that also had a tropical or subtropical storm in May. Since May storms are uncommon events, would it be reasonable to expect that similar oceanic and atmospheric conditions might have existed for seasons with a May storm event? Could anything of interest be extracted from the storm database for those seasons that would hint at likelyhoods for this season? Maybe - you decide.
With only 14 prior events, the database is quite limited - note that the storm of 1861 appears to be a database error and it was not included.
..........NEXT......LAST.......TOTAL..........LANDFALLS
YEAR...STORM...STORM.....STORMS...........US.........FLORIDA
1887.....May........Dec.......19/11/2........5/3/0........2/1/0
1889.....Jun.........Oct..........9/6/0.........3/1/0........3/0/0*
1932.....Aug.........Nov........11/6/4........5/2/1........1/0/0
1933.....Jun.........Nov........21/10/5.......6/5/1........3/2/1
1934.....Jun.........Nov........11/6/0.........6/4/0........2/0/0
1940.....Aug.........Oct..........8/4/0.........3/2/0........1/0/0
1948.....Jul..........Nov..........9/6/4.........4/3/2........3/2/2
1951.....Aug.........Oct.........10/8/5........1/0/0........1/0/0
1953.....Aug.........Dec........14/6/4........6/2/0.........5/1/0
1959.....Jun.........Oct..........11/7/2.......6/3/1........2/0/0
1970.....Jul..........Oct..........10/5/2.......3/1/0........1/0/0
1972.....Jun.........Nov..........7/3/0.........2/1/0........1/1/0
1976.....Aug........Oct..........10/6/2.......4/1/0........2/0/0
1981.....Jul..........Nov.........12/7/3........2/0/0........1/0/0
Avg.......Jul.........Nov.........12/7/2........4/2/0........2/1/0
*In 1889, one storm made landfall as a hurricane in Louisiana and as a tropical storm in Florida.
Does a tropical storm in May hint at how busy the season will be? The answer is 'no'. Two of the busiest seasons on record (1887 & 1933) had a tropical storm in May - and two relatively quiet seasons (1940 & 1972) also had a storm in May. HOWEVER, based on the limited database:
Probability of a U.S. Tropical Storm landfall: 100%
Probability of a U.S. Hurricane landfall: 86%
Probability of both a TS and a Hurricane landfall: 86%
Probability of at least 3 U.S. landfall events: 71%
For Florida:
Probability of a TS landfall: 93%*
Probability of a Hurricane landfall: 36%
Probability of both a TS and a Hurricane landfall: 29%
Probability of at least 3 landfall events: 29%
* In 1972 there was not a TS landfall in Florida - but there was a Hurricane landfall, i.e., the probability of one or the other in Florida is 100%.
Exclusive of Florida there is a probability of 64% for a U.S. Tropical Storm landfall and a 71% probability for a U.S. Hurricane landfall (and a 57% probability for both).
Does all this mean that a U.S. landfall will occur this year? Again, the answer is 'no'. Does it imply that one is quite likely? Until a season breaks the trend, I believe that the answer is 'yes'.
Place your bets, but lean toward the side of caution and stay prepared.
ED
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