01 December 1999

1999 Tropical Atlantic Activity Report

The hurricane season is officially over, so it's time for the annual Hurricane Season Summary. I sent out about 80 updates to my 27-member mailing list over the past 6 months (wow, that's a lot!); now it's time for the final one. I'm going to format the summary in the same fashion as I did last year, so it might even look a bit familiar if you were a subscriber last year. I will keep the same basic outline: the Saffir-Simpson Scale, Lifetimes and Intensities, Climatology, and Landfall. As usual, my data and typing could contain errors, so if you see a mistake, please point it out to me.

Saffir-Simpson Scale of Tropical Cyclone Intensity

CATEGORY            WINDS (mph)   PRESSURE (millibars)
------------------- ----------    ------------------
depression          23- 39       N/A
tropical storm      40- 73       N/A
1                   74- 95       > 980
2                   96-110       965-979
3                  111-130       945-964
4                  131-155       920-944
5                     >156       < 919

1. Lifetimes and Intensities
       ACTIVITY        (mph)        (mb)
-------- --------------- ------------ -------------
ARLENE   11 JUN - 18 JUN     60          1000
TD2      03 JUL - 03 JUL     35          1004
BRET     18 AUG - 23 AUG    140           945
CINDY    19 AUG - 31 AUG    140           944
DENNIS   24 AUG - 05 SEP    105           962
EMILY    24 AUG - 28 AUG     65          1004
TD7      05 SEP - 07 SEP     35          1005
FLOYD    07 SEP - 17 SEP    155           921
GERT     11 SEP - 23 SEP    150           930
HARVEY   19 SEP - 22 SEP     60           995
TD11     04 OCT - 06 OCT     35          1002
TD12     06 OCT - 08 OCT     35          1007
IRENE    13 OCT - 19 OCT    105           958
JOSE     17 OCT - 25 OCT    100           977
KATRINA  28 OCT - 01 NOV     40           999
LENNY    13 NOV - 21 NOV    155           929

2. Climatology and Statistics
The average annual number of tropical disturbances (over the past 53 years) is:
9.9 named storms
5.9 hurricanes
2.5 major hurricanes

This year, the numbers were well above that average (which has recently been the trend, except 1997)
12 named storms (14 in 1998)
8 hurricanes (10 in 1998)
5 major hurricanes (3 in 1998)

Interestingly, all 5 major hurricanes were CAT4's. There were no storms that peaked at CAT3, and none reached CAT5. It is quite rare to have 4 CAT4's in one season... the most recent year I could find that came close was 1995 with 3 of them: Felix, Luis, and Opal. You have to go back a long way before 1995 to find another comparable year (1961 had 2 CAT4's and 2 CAT5's).

There were a total of 77 named storm days (days during which a named storm was present). 43 of those days were "hurricane days", and 15 of those days were "intense hurricane days". This is 193% of the climatological mean, i.e., this season was about twice as active as the "normal" season. The average numbers are 46.9 named storm days, 23.7 hurricane days, and 4.7 intense hurricane days.

Here is a summary of highlights (VERY brief):

Arlene never made it to hurricane status, but started the season off very early, the afternoon of June 11.

Bret formed in the southern Bay of Campeche and eventually reached CAT4 before making landfall on an unpopulated region of Texas' south coast. His persistent northward motion was missed by the models that all took him westward into Mexico near Tampico.

Cindy never got close to land, but is worth mentioning because she formed so far east (19.4W). Only a handfull of storms have ever formed east of 20W.

Dennis formed just east of the Bahamas, approached the US, then headed out to sea... but not too far. He lingered off the coast of Cape Hatteras, NC for almost a week before moving westward again and making landfall just north of Cape Lookout, NC.

Floyd was tied for the most powerful storm of the year. He formed in the central Atlantic in the first week of September. Winds reached 155mph as he passed over the Bahamas, then continued his journey making US landfall as a CAT2 on Cape Fear, NC. Floyd caused incredible flooding in many of the eastern states, especially NC.

Harvey and Irene were both fairly weak storms (Harvey never even reached hurricane status), and both made landfall on the western side of the southern Florida peninsula, in the Everglades. Both storms were also forecast by models to hit the Tampa region... both stayed further south.

Jose formed very far south (10N) in the third week of October. He peaked at CAT2 intensity just as he passed over the northern Leeward Islands.

Lenny was tied with Floyd for the most powerful hurricane of the year. He formed in the western Caribbean Sea, then moved EASTWARD across the Caribbean, strengthening to a CAT4 storm with 155mph winds. He stalled over the northern Leeward Islands for 2 days, causing immense destruction. Models were initially reluctant to even make him a hurricane. That changed quickly. Lenny was the first storm of such intensity to move eastward across the Caribbean. Also, he was only the 5th major November hurricane since records began in 1886.

From Aug24 to Aug28, there were three named storms in the Atlantic, Cindy, Emily, and Dennis. Not too outstanding, but it was the most active time frame of the season (last year, there were 4 active hurricanes at the same time). Other multi-storm periods this year were: 1) Floyd and Gert were both active between 11Sep and 17Sep; 2) Gert and Harvey were both active between 19Sep and 22Sep; 3) Jose and Irene were both active between 17Oct and 19Oct. Basically, the point is that the season came in bursts of activity.

3. Landfall
There were 10 landfalling storms this year... only 5 of which made landfall on the US. Compare this to last year, when 7 of 14 named storms made landfall, and all 7 landfalls were on the US (at some point).
The first column is the storm name, second column is the date of landfall, third column is the approximate local time of landfall, fourth column is max winds (mph) at landfall, and the fifth column is the nearest location to landfall.

TD2       7/3  0000    35   Nautla, Mexico
BRET     8/22  1800   125   Padre Island, TX
DENNIS    9/4  1700    70   Cedar Island, NC
TD7       9/6  1000    35   just N of Cuidad Madero, Mexico
FLOYD    9/14  1700   140   Great Abaco Island, Bahamas
         9/16  0300   110   Cape Fear, NC
HARVEY   9/21  1700    50   Chokoloskee, FL (Everglades)
IRENE   10/14  0900    75   Cape Sable, FL (Everglades)
JOSE    10/20  1200   100   Antigua
        10/21  0800    75   US Virgin Islands
KATRINA 10/29  0800    40   Puerto Cabezas, Nicaragua
        10/31  0100    30   Xkalak, Mexico
LENNY   11/18  1300   135   Anguilla, St.Maarten, St.Bartelemy
        11/19  2300    70   Antigua

Thanks to everyone who read the updates, to those who provided the list with weather conditions/updates when the storms hit land, and to those who provided me with feedback about the updates. I also want to thank fellow CSU-ite Eric Blake for proofreading this message and supplying me with the climatological "storm days" data used in Section 2.
One more hurricane season left in the millenium. Until then, stay safe and have a great winter and spring. Hurricane Season 2000 begins June 1, the first name in the lineup is Alberto. 

Please visit my tropical Atlantic headquarters.