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Going back over some intensity estimates, here is my thinking.
* Surface data all went down long before any peak winds were received.
* The lowest pressure on land was 920 mb at Tyndall AFB. However, my best estimate is that it was not in the center of the eye (missed by about 3 miles), with the landfall point at the western end of Crooked Island. In addition, iCyclone measured 923 mb in Callaway, a bit inland and also on the western edge of the eye. The last Recon penetration had 919 mb about an hour before landfall, but it was still rapidly intensifying right up to landfall. Considering those factors, I estimate the landfall pressure was 916 mb. Using the KZC, that would equate to about 142 kt.
* The radar data at one point had 196 mph (171 kt) at about 5,000 feet. Using a 80% reduction would translate that to about 137 kt. The resolution may not have been fully resolved though.
* The highest SFMR was 138 kt, but that isn't particularly reliable near shore, hence that reading should be discarded, as should all near-landfall SFMR readings.
* The highest flight-level winds were 152 kt, in the southeast quadrant at the time of landfall. That translates to about 137 kt at the surface. Since that was in the SE quad, higher winds would be expected in the NE quad - probably about half the forward motion, ending up around 144 kt.
My conclusion: the landfall intensity I believe was 140 kt. That is based on a blend of all available data. However, category 5 winds would have been limited to beachfront areas at Mexico Beach, where there were no instruments. Category 4 winds likely occurred in more areas around East Bay, including some parts of Panama City.