SN,
The amended ML TAF issued at 1704 had prob 30 fog and the 1900 TTF SPECI had from 2000 VRB 5 kts 0500 FG
Compare that to AD, with the 1900 TTF saying all the 9's few022 NOSIG
The AD TAF had all the 9's Few030 Sct045
So you are in the planning room about to depart on your flight to AD, which is all good and ML has fog, why would you even consider ML as an alternate?