U.S. Tropical Cyclone Landfall Variability:

Transcription

1 APRIL NOTES AND CORRESPONDENCE U.S. Tropical Cyclone Landfall Variability: STEVEN W. LYONS The Weather Channel, Atlanta, Georgia April and July ABSTRACT Interannual variations in U.S. tropical storm and hurricane landfalls are examined over the interval. The highest and lowest U.S. storm and hurricane landfall years are highlighted. U.S. landfalls are times more frequent during the highest than during the lowest years. Nine major hurricanes struck the United States during the highest U.S. landfall years, one struck during the lowest U.S. landfall years. There is a positive correlation between Atlantic basin storm and hurricane frequency and U.S. storm and hurricane landfall frequency, but U.S. landfall variability explained by that relationship is small. Years with high (low) U.S. landfalls have a high (low) frequency of storm and hurricane formation in the Gulf of Mexico and the western Caribbean Sea and a high (low) percentage of them landfall along the U.S. Gulf coast. U.S. landfall frequency of Atlantic storms and hurricanes is much higher (lower) during high (low) U.S. landfall years, implying that Atlantic steering currents are more (less) favorable for U.S. landfall. La Niña conditions occurred % more often during high U.S. landfall years than during remaining years. El Niño conditions occurred % more often during low U.S. landfall years than during remaining years. Skill of inferring how many storms and hurricanes will landfall in the United States from a forecast of the number of Atlantic basin storms and hurricanes explains an average of % or less of U.S. storm and hurricane variability in a hindcast setting. Results indicate that a large portion of U.S. storm and hurricane landfall variability is related to where the storms form and whether steering currents are favorable or unfavorable for bringing them to the United States.. Introduction Tropical cyclones affect U.S. tourism, transportation, life, property, military operations, the oil industry, and the coastal ecosystem. They can devastate the coast and bring massive flooding inland. The Federal Emergency Management Agency, civil defense personnel, as well as state and local emergency managers are challenged annually with evacuation decisions when tropical cyclones threaten. The U.S. coastline has never been more vulnerable to tropical cyclones, due to increasing coastal populations, widespread building in the coastal zone, persistent beach erosion, sea level rise, and coastal subsidence (Pielke and Pielke ; Douglas et al. ). Much focus has been on U.S. major hurricane landfalls, because major hurricanes have been shown to cause a disproportionately large fraction of damage relative to their rarity (Pielke and Pielke ). This is due in part to the accumulation of wind damage with increasing wind speed, and the fact that structures have thresholds where wind damage begins. Since about % of U.S. tropical cyclone deaths have been caused by freshwater rainfall/flooding [see Rappaport () Corresponding author address: Dr. Steven W. Lyons, The Weather Channel, Interstate North Pkwy., Atlanta, GA. SLyons@weather.com and the National Hurricane Center Web site: flood.shtml]. Historically, tropical cyclone flooding has proven to be, in general, relatively independent of intensity. Weak, slow-moving storms can produce huge flood damage and numerous deaths. For example, in weakening remnants of Tropical Storm Allison caused U.S. flood damage that exceeded $ billion along with deaths (see Beven et al. ). Because of ocean wave growth behavior, coastal beach flooding and erosion from ocean waves can be more extensive for large tropical storms than for small hurricanes. Storms and hurricanes of all intensities can be costly and disruptive to the United States. For these reasons examination of both storm and hurricane landfalls is undertaken.. Background There are large interannual variations in the number of U.S. storm and hurricane landfalls. Over the past yr, an average of three storms and hurricanes have made landfall in the United States annually, about half of which have been hurricanes. Year-to-year variations in U.S. landfall frequency have been high, ranging from zero landfalls in to seven landfalls in,, and. Storm and hurricane frequency across the American Meteorological Society

2 WEATHER AND FORECASTING VOLUME TABLE. Atlantic basin and U.S. tropical storm (TS) and hurricane averages, standard deviations, and their ratio for the period. TS and hurricanes Hurricanes U.S. TS and hurricane landfalls Avg Std dev... Ratio (Avg/sigma).. Atlantic basin for the past yr has been well above the long-term average, but the percent of storms (especially major hurricanes) that have struck the United States has been below average. For example, only of the most recent Atlantic basin hurricanes has struck the United States. Three of the last major hurricanes in the Atlantic basin have struck the United States (the long-term average is one in three). This suggests that (at least episodically) the number of Atlantic basin hurricanes is not well related to the number that landfall in the United States. Bove et al. (b) focused on U.S. hurricane landfall trends through time. Their results indicate that over the past yr there has been no sign of an increase in hurricane frequency or intensity in the Gulf of Mexico. Smith () indicates that trends in hurricane landfall frequency along the U.S. east coast are slightly positive, but no intensity trends were found. Landsea et al. () expanded on this work by examining tropical cyclone development indices and their change through time. Gray et al. (, ) has led research on tropical cyclone seasonal forecasts and their causes (information online at They have shown statistical relationships among weather parameter predictors and the frequency of intense U.S. hurricane landfalls and seasonal occurrence of storms and hurricanes across the Atlantic. From through their Atlantic basin storm and hurricane forecasts have shown skill (correlation of. for June forecasts) above a forecast of average when attempting to predict damage potential to land across the Atlantic basin [see e.g., the Web site cl proj.html and Owen and Landsea ()]. They have shown that tropical Atlantic hurricanes are related to U.S. east coast landfalls, but have a poorer relationship to hurricanes that make landfall in the Gulf of Mexico. Pielke and Landsea (, ) have shown a relationship between U.S. hurricane damage and El Niño and La Niña. When averaged through time, La Niña years were associated with higher U.S. hurricane damage than were El Niño years. Bove et al. (a) confirmed the findings of Pielke and Landsea. Namely, that there is a lower probability for a hurricane or a major hurricane landfall in the United States during an El Niño (especially a strong El Niño). They calculated the probability of two or more U.S. hurricane landfalls to be about % during an El Niño, about % during neutral conditions, and about % during a La Niña over the past yr. Interestingly, yr had just one U.S. named storm landfall, but the impact was huge. In (an El Niño year and quiet hurricane season) Andrew, the costliest hurricane in U.S. history, struck Florida. Seasonal predictions of storms and hurricanes in the Atlantic basin (and other basins worldwide) reach the forefront of news at the beginning and at the peak of each hurricane season. The media and the public routinely infer the likelihood of U.S. landfalls from basinwide seasonal forecasts (despite cautions not to). The most recent example of the failure of such an inference was (an El Niño year). Despite a seasonal forecast for a below average season, seven named tropical cyclones struck the United States and an eighth impacted the United States, making it one of the highest U.S. tropical cyclone landfall years on record.. Identification of interannual variability Interannual variations in U.S. storm and hurricane landfalls are identified using the most recent portion of tropical cyclone records ( ). This recent halfcentury is the most accurate of the records. Military aircraft have flown into tropical cyclones over this entire period, although not far out at sea. Satellites have monitored tropical cyclones over about % of this period. Once satellite information became routinely available (s) there was little doubt about the number of Atlantic basin tropical cyclones in any year, where they formed, or where they moved. Questions about tropical cyclone intensity and/or whether it is warm core, cold core, or a hybrid (subtropical), along with its size, are some of the remaining ambiguities. Recently, scatterometer wind measurements from polar-orbiting satellites have improved estimates of tropical cyclone size, at least around their rain-free peripheries. Prior to the satellite era records of where in the ocean tropical cyclones formed and where they moved were not as accurate. National Hurricane Center best tracks (see Neumann et al. ; Jarvinen et al. ) are used to separate U.S. storm and hurricane landfall years into three groups: higher than average, lower than average, and the remainder. Groups are compared and contrasted.. Methodology Atlantic basin and U.S. landfalling storm and hurricane averages, standard deviations, and ratios are shown in Table. Only storms and hurricanes whose circulation center crossed the U.S. coastline are considered landfalls. Close calls and tropical depressions are excluded. Landfall frequency is grouped as average (within one standard deviation of the mean), below average (one standard deviation or more below the mean), and above average (one standard deviation or more above the mean). Distributions are not exactly normal, but.

3 APRIL NOTES AND CORRESPONDENCE TABLE. Numbers of Atlantic basin storms and hurricanes (TT), and hurricanes (H). Numbers of storms and hurricanes that struck the United States (TT*), hurricanes that struck the United States (H*), tropical storms that struck the United States (TS*), and major hurricanes that struck the United States (Hm*) for H and L years. Major hurricanes are a subset of hurricanes. Averages are shown at the bottom. Numbers of storm and hurricane U.S. coastal crossings are in parentheses. Year TT H TT* H* TS* Hm* Year TT H TT* H* TS* Hm* Avg.. () () () () () () () () () ().()... Avg... () () () () () () () (). ()... close. The average of three U.S. storm and hurricane landfalls with a standard deviation of. provides an estimate of. or more landfalls and. or less landfalls as exceeding plus and minus one standard deviation, respectively. The highest yr (five or more U.S. landfalls) and lowest yr (one or less U.S. landfalls) of this -yr study period come close to meeting these criteria.. High and low U.S. landfall years Table lists the highest and lowest U.S. storm and hurricane landfall years from to (hereafter referred to as H and L, respectively). Examination of Fig. illustrates that the outlier in the highest yr is with named cyclones and five U.S. landfalls. The year meets the criteria of five or more landfalls, but its ratio of total storms to U.S. landfalls is unlike the other nine high years. For example nine of the high years display a landfall ratio of % or higher, is down near %, which is close to the -yr mean. Conversely, all low landfall years have a FIG.. Numbers of Atlantic basin storms and hurricanes (x axis) and U.S. storm and hurricane landfalls (y axis),. An H indicates one of the highest years; an L indicates one of the nine lowest years. Dots indicate the remaining years. A dot may indicate more than one year. Slopes of.,., and. are shown. basin to landfall ratio that is less than.. It would have been possible to define high and low years based on the percent that made landfall. Primarily high years would have been defined slightly differently from the definition adopted here. However, percent of tropical storms and hurricanes that make landfall does not directly reflect U.S. landfall impacts and hence was not adopted. Removal of from the high-year group (to make like -yr samples of high and low landfalls) does little to affect the outcome of the statistics and results found in this paper, although it does increase the average number of storms and hurricanes within the -highyear sample by about one storm and hurricane per year. Some storms and hurricanes made landfall more than once. Numbers in parentheses in Table represent the total number of U.S. coastal crossings by landfalling storms and hurricanes each year. The average number of U.S. landfalls is about times higher during H than during L [e.g., an average of. (.) landfalls occurred during H (L)]. Major hurricanes (a subset of hurricanes) are also shown. Nine major hurricane landfalls occurred during H (five in the Gulf of Mexico and four along the East Coast). One major hurricane struck the U.S. Gulf coast during L. There were () U.S. landfalls during H (L), an average of. (.) landfalls per year. A total of () storms and hurricanes, a frequency of. (.) per year, formed across the Atlantic basin during H (L). This % difference in Atlantic basin storm and hurricane activity between H and L is mostly due to storm and hurricane formation differences in the Gulf of Mexico and the western Caribbean Sea. Linear scaling of U.S. landfall differences by this % difference in Atlantic basin storm and hurricane occurrences would suggest that H years might have an average of. more landfalls per year than L years, but not. more per year as was observed. By comparing the percent of Atlantic basin storms and hurricanes that made landfall in the United States during H and during L, normalized landfall differences (removal of differences of storm and hurricane

4 WEATHER AND FORECASTING VOLUME TABLE. Numbers of storms and hurricanes (T), and hurricanes (H). Percent of basinwide tropical storms and hurricanes (%T*), hurricanes (%H*), and tropical storms (%S*) that made landfall in the United States for H and L years. Averages are shown at the bottom. Year T H %T* %H* %S* Year T H %T* %H* %S* Avg. (%) Avg. (%) occurrence and the number of years included within each group) are isolated (Table ). For example % (%) of Atlantic basin storms and hurricanes and % (%) of Atlantic basin hurricanes hit the United States during H (L). The percent of storms and hurricanes that made landfall during H is. times higher than the percent that made landfall during L. The largest percent difference is evident in storm landfalls,. times higher during H years (% of storms made landfall during H in contrast to % during L). Figure plots numbers of Atlantic basin storms and hurricanes versus numbers that made landfall in the United States. Consistent with our definition L years, H years, and remaining years are clearly delineated. Interestingly, all of the remaining years (those excluding H and L years) had,, or U.S. landfalls while Atlantic basin storm and hurricane occurrences varied from to. One or zero U.S. (five, six, or seven) storm and hurricane landfalls was observed when Atlantic basin occurrences ranged from to ( to ). Separately, H, L, and the remaining years display no trend in the number of U.S. landfalls relative to the number of Atlantic basin storms and hurricanes. Separation of each of these groups based solely upon Atlantic basin storm and hurricane totals is difficult to impossible. Even if we were to define L years as those years with the highest Atlantic storm and hurricane occurrences (excluding H years), the number of U.S. landfalls would still fall well below the number of U.S. landfalls observed during H years. However, there is a small, statistically significant, positive correlation between Atlantic basin numbers and U.S. landfall numbers. The linear best-fit slope for Fig. is.. Thus for all groups combined, on average, named storms per year would indicate. landfalls, named storms per year would indicate. landfalls, and named storms per year would indicate. landfalls per year. Unfortunately scatter is large. Table shows explained variances for combinations of Atlantic basin storms and hurricanes versus numbers that made U.S. landfall. Correlations are positive for all combinations listed and most are significant at the % level, but explained variances are small. Over the - yr period, % (%) of U.S. landfalling storm and hurricane variability is (is not) explained by knowing how many storms and hurricanes occurred in the Atlantic basin. Explained variances are lowest for major hurricanes (% or less). Variances shown are diagnostic, not prognostic. They were calculated already knowing the exact number of Atlantic basin storms and hurricanes that occurred each year since. Uncertainty in predicting basin-wide storm and hurricane numbers as the season begins ( June) typically results in forecast explained variances near % (based on a forecast correlation skill of. for June). Hence, we might expect % (%) of U.S. storm and hurricane landfall variability to be explained (unexplained) by a typical June forecast of Atlantic basin tropical storms and hurricanes.. Variations in tropical cyclone origins Formation locations (proximity to the U.S. coastline), steering currents (which favor tracks to the U.S. coastline), or both must explain much of the difference in U.S. landfalls between H and L. Comparisons of U.S. storm and hurricane landfall locations during H, L, the remaining yr (R), and all years are shown TABLE. Variances explained by combinations of U.S. landfalls and Atlantic basin storms and hurricanes,. Combination Variance explained U.S. hurricanes, by Atlantic basin TSs and hurricanes %** U.S. major hurricanes, by Atlantic basin TSs and hurricanes % U.S. TSs and hurricanes, by Atlantic basin TSs and hurricanes %* U.S. tropical storms, by Atlantic basin TSs and hurricanes %* U.S. hurricanes, by Atlantic basin hurricanes %* U.S. major hurricanes, by Atlantic basin hurricanes %** U.S. major hurricanes, by Atlantic basin major hurricanes % * Significant a the % level based on an F test. ** Significant at the % level based on an F test.

5 APRIL NOTES AND CORRESPONDENCE TABLE. Average number of storms and hurricanes that struck the U.S. Gulf coast, east coast, and all coasts for H, L, the remaining yr, and all years for the period. H L R All Gulf landfalls.... East coast landfalls.... Total.... in Table. About % of U.S. storm and hurricane landfalls occurred in the Gulf of Mexico during H years, R, years and all years groupings. Ninety percent of U.S. landfalls occurred in the Gulf of Mexico during L years. Hence, Gulf of Mexico landfalls are critical when determining U.S. tropical cyclone impacts. Differences in storm and hurricane formation areas between H and L are shown by plotting origins and end points (or first U.S. landfall positions) for H (Fig. a) and separately for L (Fig. b). Forty-nine storms and hurricanes originated in the Gulf of Mexico and Caribbean during H years, while only originated FIG.. (a) Origins (open circles) O and final locations (or first U.S. landfall location; filled circles) of storms and hurricanes during H years. Final locations are plotted to near N. Storm and hurricane counts and frequencies per year are shown for the Gulf of Mexico and the Caribbean Sea, the Atlantic north and south of N, and the entire Atlantic. (b) As in (a) except for L.

6 WEATHER AND FORECASTING VOLUME FIG.. (a) Origins of storms and hurricanes that eventually made U.S. landfall during H. Filled circles represent origins that eventual became U.S. major hurricane landfalls. Storm and hurricane counts and frequencies per year are shown for the Gulf of Mexico and the Caribbean Sea, the Atlantic north and south of N, and the entire Atlantic. (b) As in (a) except for L. there during L years. That equates to. origins per year during H versus. origins per year during L. This difference is statistically significant at the % level, based on a sampling of storm and hurricane differences from random -yr groupings from to (of random samples of yr, none exceed a difference of greater than. origins per year). Thirty-six of (%) Gulf of Mexico and Caribbean Sea storms and hurricanes made landfall in the United States during H. Five of (%) Gulf of Mexico and Caribbean Sea storms and hurricanes made landfall in the United States during L. Hence, U.S. storm and hurricane landfalls during the -yr period are strongly modulated by the number of storms that originate in the Gulf of Mexico or Caribbean Sea and the fraction of them that finally hit the United States (which is related to steering currents favorable or unfavorable for U.S. landfall). Close to the same frequency of storms and hurricanes formed in the Atlantic Ocean in H as in L (e.g.,. origins per year during H compared to origins per year during L). During H years,. storms and hurricanes per year originated in the deep Tropics (at or south of N). This compares to. origins per year there during L. During H, an average of three storms

7 APRIL NOTES AND CORRESPONDENCE and hurricanes per year originated north of N in the Atlantic. During L there was an average of. origins per year north of N. Most interesting are the formation locations for storms and hurricanes that eventually made U.S. landfall (Figs. a and b). Immediately obvious is the high frequency of landfalls originating in the Gulf of Mexico and tropical Atlantic during H compared to L. For example, during H, (an average of. per year) U.S. storms and hurricanes originated in the Gulf of Mexico or the Caribbean Sea. Conversely, during L years, (an average of only. per year) U.S. storms and hurricanes originated in the Gulf of Mexico or the Caribbean Sea. The frequency of U.S. landfalls originating in the Gulf of Mexico or the Caribbean Sea was about times greater during H than during L. Eight (. per year) storms and hurricanes that originated north of N eventually made landfall in the United States during H. In contrast (. per year) storms and hurricanes did so during L. Fourteen storms and hurricanes that eventually hit the U.S. coast originated in the tropical Atlantic south of N during H (an average of. per year). That was % of all tropical Atlantic storms and hurricanes during H. In contrast during L only one U.S. hurricane originated in the tropical Atlantic, which was an average of. per year. That was only % of all tropical Atlantic storms and hurricanes during L years. This difference is also highly significant at least to the % level. Hence, the difference in tropical Atlantic storms that eventually hit the United States is also important (%), but the total number of U.S. landfalls from this area does not compare to those originating in the Gulf of Mexico and the northwest Caribbean Sea (%). The number of storms and hurricanes that curved north of N into the North Atlantic indicates that did so during L and did so during H. The percent difference is % higher for L years than during H years. Obviously these results strongly imply that Atlantic basin steering currents favored U.S. landfalls during H years as compared to L years by a ratio of about to. During H (L), tropical cyclones dissipated over open water south of N in the Atlantic, in the Caribbean or in the Gulf of Mexico, indicating that the percent of systems decaying over water before having a chance to landfall in the United States was roughly the same for each group. TABLE. (top) ENSO phase and amplitude for H and L years. ENSO index is adopted from a Jul Sep average defined by the Climate Prediction Center; N indicates a neutral phase, C indicates a cold phase in the direction of La Niña, and W indicates a warm phase in the direction of El Niño. Strong is indicated by a plus sign, weak is indicated by a minus sign. (bottom) Total count and percent occurrence of ENSO phases for H, L, and remaining years (R). H L R H yr W C N C N N N C C W L yr N N W C C N W W W Neutral (%) Cool (%) Warm (%) / / / / / / / / /. El Niño Southern Oscillation connections Table displays ENSO phases as defined by the National Oceanic and Atmospheric Administration/National Weather Service/National Centers for Environmental Prediction (NOAA/NWS/NCEP) Climate Prediction Center for H years and for L years (information online at products/analysis monitoring/ensostuff/ensoyears. html). Neutral and cool ENSO phases were equally frequent during H years. A warm ENSO phase was most frequent during L. A neutral ENSO phase, followed closely by a warm phase, was most frequent during the remaining yr. H (L) years were % (%) more likely than L (H) years to occur during a La Niña (an El Niño). The largest percent separation among ENSO phases was the warm ENSO phase during L years. These percentages are based on already knowing the ENSO phase and amplitude. In a real-time forecast setting uncertainty in forecasting ENSO phase and strength through the Atlantic basin hurricane season can be problematic. These results are consistent with previous research on ENSO effects on U.S. landfalling hurricanes.. Conclusions U.S. storm and hurricane landfalls were grouped into the highest yr, into the lowest yr and into remaining years within the most recent -yr record. U.S. storm and hurricane landfalls were about times more frequent in high landfall years than in low landfall years. Major hurricanes struck the United States nine times during high U.S. landfall years (half originated in the Gulf of Mexico and the Caribbean Sea, and half originated in the Atlantic), but only once during low U.S. landfall years. Other differences between high and low U.S. landfall years are summarized below. ) Storm and hurricane formation was about times more frequent in the Gulf of Mexico and the western Caribbean Sea during high U.S. landfall years than during low U.S. landfall years, and a higher percentage of these storms made landfall in the United States during H years (%) than during L years (%). This result is significant at least to %.

8 WEATHER AND FORECASTING VOLUME ) Twenty-two of (%) Atlantic storms and hurricanes tracked to the U.S. coast during high U.S. landfall years, but only of (%) did so during low U.S. landfall years. This strongly implies that Atlantic steering currents were more efficient at bringing storms and hurricanes to the U.S. coast during high landfall years. ) Approximately. storms and hurricanes per year formed in the Atlantic Ocean during high U.S. landfall years, and similarly per year formed there during low U.S. landfall years. The big difference was in the Gulf of Mexico and the western Caribbean Sea. During high U.S. landfall years an average of. origins per year were observed there, in contrast to. origins per year during L years. ) La Niña (El Niño) conditions were % (%) more frequent during high (low) U.S. landfall years than during low (high) U.S. landfall years. ) U.S. storm and hurricane landfall frequency is positively correlated with Atlantic basin tropical cyclone frequency, but over the past yr, level of success in inferring U.S. storm and hurricane landfall frequency from Atlantic basin storm and hurricane frequency is low. Results strongly suggest that forecasting a high portion of variability in U.S. storm and hurricane landfalls requires at least ) accurately forecasting variations in storm and hurricane origins, ) accurately forecasting variations in steering currents favorable or unfavorable for moving storms and hurricanes to the U.S. coastline, and ) accurately forecasting the phase and amplitude of ENSO through the Atlantic hurricane season. For any specific year, it is dangerous to infer numbers of U.S. landfalling storms and hurricanes from numbers that occur or are expected to occur across the Atlantic basin. Acknowledgments. Thanks to The Weather Channel for financial support for this research and to anonymous reviewers for helpful suggestions that improved this note. REFERENCES Beven, J. L., S. Steward, M. Lawrence, L. Avila, J. Franklin, and R. Pasch, : Atlantic hurricane season. Mon. Wea. Rev.,,. Bove, M. C., J. J. O Brien, J. B. Eisner, C. W. Landsea, and X. Niu, a: Effect of El Niño on U.S. landfalling hurricanes, revisited. Bull. Amer. Meteor. Soc.,,., D. F. Zierden, and J. J. O Brien, b: Are Gulf landfalling hurricanes getting stronger? Bull. Amer. Meteor. Soc.,,. Douglas, B., M. Kearney, and S. Leatherman, : Sea Level Rise, History and Consequences. International Geophysics Series, Vol., pp. Gray, W. M., C. W. Landsea, P. W. Mielke, and K. J. Berry, : Predicting Atlantic seasonal hurricane activity months in advance. Wea. Forecasting,,.,,, and, : Predicting Atlantic basin seasonal tropical cyclone activity by August. Wea. Forecasting,,. Jarvinen, B. R., C. J. Neumann, and M. A. S. Davis, : A tropical cyclone data tape for the North Atlantic basin, : Contents, limitations, and uses. NOAA Tech. Memo. NWS NHC, Coral Gables, FL, pp. Landsea, C. W., R. A. Pielke Jr., A. M. Mestas-Nunez, and J. A. Knaff, : Atlantic basin hurricanes: Indices of climatic changes. Climatic Change,,. Neumann, C. J., B. R. Jarvinen, C. J. McAdie, and G. R. Hammer, : Tropical Cyclones of the North Atlantic Ocean,. Historical Climatology Series, No., NOAA/NWS/ NESDIS, pp. Owen, B. F., and C. W. Landsea, : Assessing the skill of operational Atlantic seasonal tropical cyclone forecasts. Wea. Forecasting,,. Pielke, R. A., Jr., and R. A. Pielke Sr., : Hurricanes their Nature and Impacts on Society. John Wiley and Sons, pp., and C. W. Landsea, : Normalized hurricane damages in the United States:. Wea. Forecasting,,., and, : La Niña,ElNiño, and Atlantic hurricane damages in the United States. Bull. Amer. Meteor. Soc.,,. Rapport, E. N., : Loss of life in the United States associated with recent Atlantic tropical cyclones. Bull. Amer. Meteor. Soc.,,. Smith, E., : Atlantic and East Coast hurricanes : A frequency and intensity study for the twenty-first century. Bull. Amer. Meteor. Soc.,,.