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Tropical Cyclones of the North Atlantic Ocean

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U.S. DEPARTMENT OF COMMERCE JOHN T. CoNNOR, Secretary WEATHER ·BUREAU RoBERT M. W BITE, Chief TECHNICAL PAPER NO. 55 Tropical Cyclones of the North Atlantic Ocean Tracks and Frequencies of Hurricanes and Tropical Storms, 1871-1963 GEORGE W. CRY Laboratory of Climatology, U.S. Weather Bureau WASHINGTON, D.C. 1965 For sale by the Superintendent of Documents, U,S. Government Printing Office, Washington, D.C., 20402 - Price 70 cents PREFACE Scope.-This paper seeks to consolidate records of the occur­ purpose of this paper is to provide this information in a convenient rences and paths of tropical cyclones of storm and hurricane force form. in the North Atlantic region, and to provide information on the U.S. Weather Bureau Technical Paper No. 36 [9] provided the frequencies and seasonal distributions of these relatively rare, but starting point for the present study. The general outline of that important, disturbances. work has been maintained, but additional material has been utilized Tropical cyclones are significant features of the climate of much of to extend information on tropical cyclones backward to include the the eastern and southern United States as well as of most other years 1871 through 1885 and forward to include the years 1959 areas bordering the western edge of the Atlantic, the Caribbean, and through 1963. New material also provided the basis for slight Gulf of Mexico. The destructive features of a single fully-developed modifications of a number of the tropical cyclone paths shown in hurricane-extremely strong winds, torrential rainfall, and high [9]. New text, tables, figures, and charts have been prepared, and tides and waves-may pose a threat to life and property over an a short discussion of possible trends in tropical cyclone frequencies area of more than 30,000 square miles, and to more than 30 million has been included. The decadal (10-day, 10-yr.) maps of Technical people. Tremendous amounts of property damage have resulted Paper No. 36 have not been included in this paper. Consequently, from tropical cyclone activity-ranging upward to near $1 billion during the passage of a single hurricane. More than 12,000 persons Technical Paper No. 36 remains the only source of this type of data. have lost their lives in hurricanes in the United States since 1900, Acknowledgments.-The interest, encouragement, and advice of and almost 6,900 deaths were attributed to a hurricane in the Dr. H. E. Landsberg, Director of Climatology, H. C. S. Thorn, Caribbean as recently as 1963. W. H. Haggard, A. I. Cooperman, and W. C. Palmer are appreciated. All activities in the regions subject to periodic tropical cyclones­ Thanks are due C. F. Kambic for his assistance in the collection and business, commerce, industry, agriculture-can benefit from more assembly of data. The support of theNational Hurricane Research complete information concerning their occurrence. The primary Laboratory, Dr. R. C. Gentry, Director, is gratefully acknowledged. ii CONTENTS Page PREFACE_____________________________________________________ ii 1. TROPICAL CYCLONES_____________________________________ 1 2. CLASSIFICATION OF TROPICAL CYCLONES______________ 2 3. SOURCES AND QUALITY OF DATA_______________________ 3 4. NORTH ATLANTIC TROPICAL CYCLONE TRACKS_______ 5 5. NORTH ATLANTIC TROPICAL CYCLONE FEATURES____ 6 Formation ____ ~--------------------------------------------- 6 Hurricane intensity__ __ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ __ _ _ _ __ _ _ _ __ __ _ _ _ __ _ _ 12 Recurvatures and erratic movements______________ __ _ _ _ _ _ _ _ __ 18 6. FREQUENCIES OF NORTH ATLANTIC TROPICAL CY- CLONES__________________________________________________ 25 Monthly and annual frequencies______________________________ 25 Dailyfrequency_____________________________________________ 28 Tropical cyclones affecting the United States___________________ 29 Trends in North Atlantic tropical cyclone frequency_____________ 31 REFEREN0ES_ _ __ _ _ _ __ _ _ _ _ __ _ ___ __ _ _ _ _ __ ____ __ _ ___ __ _ _ __ __ _ _ _ 33 CHART SERIES A-Tracks of North Atlantic Tropical Cyclones, By Years, 1871-1963 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 36 CHART SERIES B-Tracks of North Atlantic Tropical Cyclones, By Months and Other Calendar Periods__________________________ 129 iii TROPICAL CYCLONES OF THE NORTH ATLANTIC OCEAN GEORGE W. CRY Laboratory of Climatology, U.S. Weather Bureau, Washington, D.C. I. TROPICAL CYCLONES Any closed atmospheric circulation in the Northern Hemisphere mon feature of tropical cyclones of all intensities. Tides produced in which the winds move counterclockwise around a center of pres­ by an intense hurricane in coastal areas may reach levels of 10 to sure lower than the surrounding area is called a cyclone. A tropical 25 feet above normal. cyclone is a circulation developing over tropical oceanic regions The distributions of winds, pressure, and temperature tend to be where temperature and moisture conditions are almost uniform over circularly symmetric in tropical cyclones because of the development large areas. of these storms in regions of nearly constant air mass properties. The terms "cyclone" or "tropical cyclone" signify nothing as to the Another unique feature is the central "eye." The pattern of winds intensity of associated winds or weather. Cyclones of the middle does not converge to a single point, but becomes tangent to the eye latitudes, deriving energy primarily from the contrasts of tem­ boundary at a radius of some 5 to 10 miles or more from the exact perature and moisture in the air masses present within the circula­ st9rm center. In the eye there is little wind or rain; the sky may tion, may range from weak, barely discernible whirls to massive, intense vortices of immense power often covering an area well over become clear in some cases; temperatures at the surface are usually 1,000 miles in diameter. Tropical cyclones, with energy derived a few degrees higher, and the moisture content of the air lower, than primarily from the latent heat of condensation of water vapor, in the encircling region of strong winds. are generally smaller in areal extent, ranging from 60 to 600 miles in The exact processes and mechanisms for tropical cyclone formation diameter at maturity, and only rarely exceed 1,000 miles in diameter. are not yet completely known. Detailed physical and dynamical The speed of the maximmn winds near the center of the storm has been descriptions of the formation, structure, and movement are beyond estimated at more than 200 m.p.h. (175 kt.) in well-developed the scope of this work. Recent discussions of present hypotheses hurricanes. Torrential rainfall over a considerable area is a com- are given by Riehl [34] and Yanai [59]. 1 2. CLASSIFICATIONS OF TROPICAL CYCLONES Various methods for identification of the different stages of geographical locations of the various stages of the life cycle-where tropical cyclones have evolved over the years in the several regions the cyclone was weak, well-developed, decaying, or being modified of the world subject to these storms. All atmospheric circulations by the intrusion of air from source regions outside the Tropics­ have a "life cycle" of development, intensification, maturity, and were given. decay or modification. Technical criteria have been formulated to Such a summary of tracks without some estimation of intensity identify these various stages. along each path, when any data are available from which inferences The strength of the maximum winds is also used extensively to of intensity can be drawn, is lacking in an important aspect of the classify tropical cyclones. Although universal agreement in terms overall description of the storms, because a hurricane normally has not been attained, most classifications are similar, with only does not retain winds of hurricane force throughout its existence. moderate differences in threshold values for various intensities. Intensity estimates have been made in this paper. The criteria for The strongest stage, with sustained surface wind speeds of 74 m.p.h. the different stages and the periods used are given in table 1. A (64 kt.) or more, is called hurricane in the North Atlantic region, combination of life cycle and intensity criteria, these stages conform including the Caribbean Sea and the Gulf of Mexico, in the eastern to the thresholds and terminology in current use in the North Atlantic North Pacific, and in the western South Pacific. Cyclones of com­ region. parable intensity are called typhoons in the western North Pacific, The development and dissipation of tropical cyclones are dependent and simply cyclones in the Bay of Bengal, the Arabian Sea, and the on location and the interaction of the storms with the surrounding southern Indian Ocean. Local names for tropical cyclones of hurri­ environment. For example, tropical cyclones remaining at low cane force include baguio in the Philippine Islands. latitudes may progress in intensity from tropical depression to Tropical cyclones with sustained winds in the range 39 to 73 tropical storm, to hurricane, then back to tropical storm as they begin m.p.h. (34 to 63 kt.) are called tropical storms in the North Atlantic to lose intensity, and then to tropical depression (dissipation). Those region; circulations with maximum sustained winds up to 38 m.p.h. cyclones moving northward out of the Tropics may follow these same (33 kt.) are tropical depressions. These categories are also used in the North Pacific tropical cyclone regions. TABLE 1.-Terms used to describe intensity stages of tropical cyclones Riehl [33], Dunn [11], Dunn and Miller [13], and U.S. Weather Criteria and period used Bureau [52] discuss the life cycle and classifications of tropical Stage of development cyclones. Tropical depression (develop- The weak stage of a tropical cyclone with a definite closed surface circu­ ment).
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