I don't think Irma will continue to burrow WSW as deeply as last 12 hours for several reasons. First, historic tracks for the hurricanes of the similar strength in the same part of the Atlantic basin (though not many) did not continue south of due west. Second, the ridge north of Irma that has nudged her south of west appears to have a bit of weakness a few degrees either side of 50W, This very subtle weakness along the "belly" of the Bermuda high could allow her to track above 17N a bit longer during the next 24 hours. If this pans out, Irma may not bottom out at 16.4N as currently forecast in 36 hours.