92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Sunday, 22 January 2012
Analysis of Climate Indices Associated with Hurricanes Making Landfall in the U.S. during 1951-2010
Hall E (New Orleans Convention Center )
Nicholas B. Zweber, St. John's University, Collegeville, MN; and C. H. Paxton and J. M. Collins

Atlantic hurricanes (category 2 or higher) striking the U.S. show a definitive decadal pattern. This inverse pattern varies by decade between the East Coast of the United States and the Gulf of Mexico. Eight hurricane seasons of Gulf of Mexico landfalls and nine seasons of Atlantic coast landfalls were chosen to represent the seasonal differences between the two coasts during 1951-2010. Atmospheric anomalies, logistical regressions, and a negative binomial distribution were evaluated to determine the most accurate atmospheric predictors of the location of landfall and of the number of hurricanes occurring within a month.

This research indicates that the climate indices relating to sea surface temperatures are the most significant predictors of landfall and the amount of hurricanes that occur. The East Central Tropical Pacific sea surface temperature (NINO3.4) is an accurate predictor in determining the location of a hurricane (no landfall, Gulf Coast, or Atlantic Coast). An increase in the Eastern Tropical Pacific sea surface temperature (NINO3) decreases the likelihood that a hurricane will reach landfall. These results adhere to the El Niņo/La Niņa effect. Fewer hurricanes are observed during an El Niņo period due to warmer sea surface temperatures occurring in the eastern tropical Pacific. This supports these findings that increasing the indices of NINO3 and NINO3.4 decrease the likelihood of hurricanes reaching landfall in the U.S.

This research also demonstrates the differences in the evolution of hurricane season in which landfalls are distinctly Atlantic Coast or distinctly Gulf of Mexico Coast. The sea surface temperature anomalies indicated the onset of La Niņa prior to the peaks of hurricane season for both landfall areas, but the onset was later for the Gulf of Mexico landfall seasons. Negative sea level pressure anomalies over the southern Pacific Ocean also demonstrated a later onset of La Niņa in the Gulf of Mexico region. Persistent sea level pressure anomalies were present over North Africa for the Atlantic Coast cases but not for the Gulf Coast cases. These observed differences in the evolution of hurricane season for each coast could explain the inverse decadal pattern in Atlantic hurricanes.

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