Fabian was steered on a westward to
west-northwestward heading for several days, in the latter part of August, by
deep easterlies to the south of a subtropical ridge. The forward speed gradually
slowed as the tropical cyclone neared a weakness in the subtropical ridge
produced by a mid-level cyclonic circulation over the southwestern North
Atlantic, in early September. Then, the hurricane turned toward the northwest
while continuing to decelerate around September 3rd.
An investigation of ensemble spread shows a great deal of uncertainty along the
northern side of the eastern US/western Atlantic anti-cyclone, however, this
uncertainty has little impact on the track of Fabian. The ET KF selected the
area in and to the north of the storm as the best region to take additional
observations. These observations would help solidify the analysis of the storm,
and it's asymmetry.
The ET KF indicates numerous other regions where observations would be
beneficial, the most significant to the north of Fabian. This area is the edge
of this ridge feature, and these observations likely will help determine the
stronger and weaker areas along the ridge.
The flight sampled both Fabian and the region of higher ensemble spread to the
north of Fabian.
