I am very familiar with STN, and this is the smoking area, by the way!
With that wind, on a Easter Fridayafternoon with anything from 1 to 3000 people at departure level checking in and lining up for security in the west part of the building, I can defiantly see the need to evacuate into the departure hall.
The slight inconvenience of sorting out the mess later after a happy ending is academic!
If you want to evacuate the check-in at STN your only option is out he front, if not using plan B, as executed here.