The Deadliest Atlantic Tropical Cyclones, 1492-1996
Contents
- Introduction
- Tropical Cyclone Terminology
- Casualty Information
- Storm Lists and Statistics
- Conclusions
- Acknowledgements and References
- Appendix 1: Cyclones with 25+ deaths
- Appendix 2: Cyclones that may have 25+ deaths
- Notes to the Appendices
- References to the Appendices
2. Tropical Cyclone Terminology
The United States National Weather
Service technical definition of a
tropical cyclone (National Weather
Service Operations Manual C-41 1993) is: "A nonfrontal, warm-core, low
pressure system of synoptic scale, developing over tropical or subtropical
waters and having a definite organized circulation." In practice, that
circulation refers to a closed, counterclockwise (in the northern
hemisphere) airflow at the earth's surface.
Meteorologists generally recognize three classes of tropical cyclones
stratified by their highest one-minute average surface wind speed.
Tropical Depressions have maximum wind speed less than 39 mph (and,
in practice, generally greater than 20-25 mph). Maximum wind speed from 39
to 73 mph characterizes
Tropical Storms.
Hurricanes have wind
speeds of at least 74 mph. Of the defining criteria, the closed nature of
the circulation in weak systems, the thermodynamic structure, and the
precise intensity cannot always be determined objectively. For this
compilation, the publication Tropical Cyclones of the North Atlantic
Ocean (Neumann et al. 1993) and the associated
NHC Best Track data set
served as the final authorities for Atlantic
tropical cyclone histories back to 1871.
These definitions are more quantitative than the terminologies of the past.
Many early reports, especially from non-meteorological sources, referred to
"hurricanes" without providing elaboration. Sometimes, hurricane meant any
storm of apparently exceptional ferocity (such as a powerful high-latitude
storm of non-tropical origin or a "severe" thunderstorm) that, perhaps,
produced what we now consider hurricane force winds. Others used
subjective terms like "a terrific gale"
or winds "blowing a perfect hurricane" (e.g., Milner and Sowerby 1863). It
is unclear in these instances whether the current requirements for a
tropical cyclone were satisfied. Occasionally, however, an especially
descriptive account added confidence to the interpretation, as in a summary
printed in the 6 November 1761 issue of Lloyd's List
3
(note: in keeping with the style of the original text, "§" is used to
approximate the archiac form of the letter "s"):
Capt. Young, arriv'd at Bri§tol from Guadalupe, came out the 17th
of Sept. in Company with a Fleet of 26 Sail, mo§t of them for
England, under Convoy of the Griffin Man of War, who was to §ee
them as far as Lat. 28; but on the 27th ditto, in Lat. 22, they met
with a heavy Gale of Wind, which began at the N. W. and veered all
round the Compa§s to the S. E. in which the Fleet were §cattered,
and §everal lo§t their Topma§ts.
The next Morning he §aw only nine
Ve§§els with the Man of War; and the Captain adds, That by the
Smartne§s of the Gale, and the Wind's flying about round the
Compa§s, he apprehends it was the Tail of an Hurricane.
Information about storm duration was helpful, too. The very
long duration of the inclement weather described in the following
passage is more consistent with a "cut-off" low than with a
tropical cyclone:
Falmouth, 6th January. Arrived the Hyena, Captain Thompfon. Left
St. Kitts on the 30th November, with about thirty fail of Veffels
under her Convoy; but a Tempeft of Wind, on the 17th of December,
in Lat. 32 feparated them; a Storm of an uncommon Sort, that lafted
from that Period to this Day; the Damages of the Hyena are fo
great, it was with difficulty fhe was brought into Port, and much
is to be apprehended for the Fleet.
(Lloyd's List, 11 January 1782)
Accounts that included weather observations, such as ship
reports based on the Beaufort scale (introduced in 1805) or
barometric pressure measurements, helped to clarify the nature of
some rough weather events. These data were most often found in
meteorological studies, like Ludlum (1963) and Millas (1968), which
provided many well-documented and corroborating descriptions.
This study adhered to several guidelines that minimized
subjectivity and simplified the analysis. Every entry in the
Appendices had a documented association with bad weather that was,
or could reasonably be, related to a tropical cyclone. This
requirement eliminated many cases from further consideration, even
those where the remaining evidence (in the example below, the date
and location of a loss of multiple ships) tempted us to attribute
the disaster to a tropical cyclone:
The Duke of Cumberland, (Captain) Ball, a Letter of Marque of
Briftol, laft from the Canaries for Virginia, was loft in September
laft nine Leagues to the Southward of Cape Henry; the Captain,
Surgeon and twenty three Men were drowned, and 21 faved. about
the fame time were alfo loft a Snow and a Brig, Names unknown, and
all the Crew of the former perifh'd.
(Lloyd's List, 11 November 1757)
Wherever helpful, the data and descriptions provided by the sources are
reprinted verbatim. (Unfortunately, by doing so, we also pass along some
information that either originally [or over the years] was [re]recorded
incorrectly. Conflicting accounts were noted in, and by, several sources
and the associated uncertainties are reflected in
Appendix 1. We hope, however, that by
providing all relevant reference information, the reader will gain as
thorough a documentation of the event as possible.)
Footnotes
are included to point out special conditions. For
example, the footnote "c" indicates that the tropical nature of a
storm was in doubt for at least part of the event. Often, it
applies to storms moving poleward from about 40-45N, where weather
systems generally encounter relatively cold ocean waters (°C)
and tropical cyclones transform to
extratropical
cyclone status.
The track data of Neumann et al. (1993) show that Atlantic
tropical cyclones are almost exclusively a warm-season event, as
implied by the mariner's poem (Inwards 1898):
June too soon.
July stand by.
August look out you must.
September remember.
October all over.
The last line may be more ambiguous than helpful. In some Octobers, "all
over" seems to describe the spatial distribution rather than a certain
cessation of activity. The NHC officially defines the hurricane season to
run from June through November. Tropical cyclones outside that period are
relatively rare and mostly limited to low latitudes. In this study, when
lacking evidence to the contrary, storms between December and May were
eliminated from further consideration.
Only in obvious circumstances was a report purportedly about a tropical
cyclone rejected outright. The following account refers to a "Hurricane",
but the storm's date and location are inconsistent with our expectation of a
tropical cyclone:
Plymouth (England), Jan. 5. Laft Night it blew a Hurricane; almost
every Ship in the Harbour drove.
(Lloyd's List, 7 January 1791)
The concept of storm track and the difference between storm motion and
circulation remained obscure until Benjamin Franklin's conclusions of the
mid-18th century (see, Ludlum 1963, p. 22) were extended and formalized by
Redfield (e.g., 1836), Reid (1841) and others. In addition, with
communications generally limited for centuries to the line of sight, storms
almost always moved faster than did the information about them. The first
words about "The Great Hurricane" of 10-16 October 1780 did not appear in
Lloyd's List (published twice a week at that time) until the 19
December issue, and new reports appeared through 13 April 1781.
These limitations certainly contributed to the peril of people in the path
of an oncoming storm. One impact on this study was to introduce uncertainty
in some instances about whether contemporary storm accounts from a region
referred to a single tropical cyclone or possibly to multiple systems. (The
Lloyd's List issues from December 1780 through April 1781 describe
losses in the Caribbean Sea and adjacent islands. We now know that in
addition to the Great Hurricane, two more of this hemisphere's most
notorious storms occurred in that region during October 1780; see, Millas
1968). Another example occurred in 1785 when a storm devastated the area
from St. Croix to Cuba during the last week of August (The Daily
Universal Register). On the 2nd of September, a "savage" storm struck
the Delaware coast (Seibold and Adams 1989). Two disturbances could be
responsible for these events. Alternately, the tracks of more recent storms
suggest that a single tropical cyclone could have been the culprit. Cases
where uncertainties persist about the number of storms involved were entered
into the catalog and assigned the
footnote "z".
(Please see the NHC Glossary page for other
terminology in this report.)
3 This account, like several that follow in the text and in
Appendix 2, is shown in an older style of English, presented by the
source, where "f" sometimes represents "s".
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