U.S. Tropical Cyclone Landfall Variability: 1950–2002

Abstract

Interannual variations in U.S. tropical storm and hurricane landfalls are examined over the interval 1950– 2002. The 10 highest and 9 lowest U.S. storm and hurricane landfall years are highlighted. U.S. landfalls are 6 times more frequent during the 10 highest than during the 9 lowest years. Nine major hurricanes struck the United States during the 10 highest U.S. landfall years, one struck during the 9 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 19% more often during high U.S. landfall years than during remaining years. El Niño conditions occurred 10% 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 18% 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.