You sure picked an interesting case study! Ethel formed in the central GOM on September 14th at 12Z at 23.9N 90.6W with sustained winds of 40 knots - based on observations from the automated marine platform. Unfortunately the Storm Summary does not give the time of the Recon report - just that it was in the afternoon.
From the best track files, here is what Ethel did:
14/18Z 25.6 89.7 75 knots
15/00Z 27.0 89.1 110 knots
15/06Z 28.1 88.9 140 knots, pressure 981mb
15/12Z 29.1 88.9 80 knots
15/18Z 29.9 89.0 60 knots

Ethel intensified 100 knots in 18 hours. When the dry air entrained into the system it significantly reduced the intensity, and fortunately this was prior to landfall (near Biloxi, Mississippi). But note the 06Z surface wind speed of 140 knots (160mph = Cat V) against a pressure of only 981mb. There are a few noted exceptions to the wind/pressure relationship, but in this case the surrounding pressure must have been uncommonly high. Since this storm was before the satellite era, Ethel must have continued her rapid intensification long after the Recon report and the core wind speed would have to have been extrapolated from ship reports or fixed platforms - its the only thing that I can think of to allow for such a high wind speed.

And of course Ethel formed quite a bit more to the south of the current near-shore activity. Any other ideas out there?
Cheers,
ED