Isolating Factors for the Northward Turn Timing and Location of Hurricane Irma

Operational and experimental models supported by the Hurricane Forecast Improvement Project (HFIP) provided better-than-average track forecasts for Hurricane Irma. However, forecasts of the timing and location of Irma’s northward turn were widely uncertain from model guidance even as close as 48 hours before landfall. The timing and location of this northward turn directly determined where Irma made landfall on the Florida Peninsula. In this study, we have designed a set of experiments to explore the key synoptic factors for the sharp northward turn of Irma before its landfall and the continuous northward track through the Florida Peninsula. Our preliminary results suggest that the modulation of the Bermuda high and North American mid-latitude trough by multi-storm interactions with Jose and Katia played an important role in the motion of Irma.