Characterizing the Variations of North Atlantic Tropical Cyclone Motion

It is well-documented that tropical cyclone (TC) motion is primarily governed by the environmental steering flow including effects from beta drift and storm structure. This study analyzes climatological variations in North Atlantic TC motion according to storm location, TC lifecycle, seasonal cycle and its interannual variations (with regard to El Niño Southern Oscillation [ENSO] and the Atlantic Warm Pool [AWP]). The National Hurricane Center’s Atlantic Hurricane Database (HURDAT2) is used to examine 6-hourly fixes of all TCs that developed in the North Atlantic from 1988 – 2014. The results show that 81% of TCs maintain a propagation speed of < 20 mph, with fast-moving (> 40 mph) TCs found north of 30 °N where the environmental steering flow is stronger. Slow-moving (< 10 mph) TCs exist across a wider range of latitudes extending from equatorial latitudes to 40 °N. When considering the interannual variations of TC motion, there is a higher frequency of TC fixes during cold relative to warm ENSO years across all ranges of translation speed. The largest fractional change in frequency between the cold and warm ENSO phases occurs for TCs traveling in the range of 10 – 20 mph. There is, however, a significant increase in frequency across all categories of TC translation speed in large relative to small AWP years. This would suggest that AWP has a more significant impact on North Atlantic TC translation speed than ENSO variations.