Has anyone found the source of the explosion sound?
I was at the Hotel and got an alert that there was a relay beacon nearby; southwest. When I found it roughly between the Hotel and the Concert location; I saw the remnants of a large fireball roll above the trees accompanying that explosion sound farther to the SW.
Can anyone confirm?
Yes! Happens all the time. It’s in the town with the lighthouse - they regularly blow up some storage tanks. I think it is meant to be a “danger” when you have the mission there (to ring the bell or whatever). When you enter the town, there is quite a lot of “trade” so you are tempted to go to ground in one of the Portkabins to fight them, whereupon you get blown to smithereens. But delightfully, they do it all the time - it gives you the sense of something going on when you’re not there. I like it…
When game world is initially loaded (when you Continue your game), it is loaded in a state where no missions are done. Once you reach near the spot on map which has different setting compared to the initial setting, game checks your completed missions and then loads the mission specific event, so when you reach that spot, it is as it should be post mission.
There are few such spots on the map: RÖ, FOA5, Himarvet, Tärnboda skans.
The fireball and following explosion you witnessed is part of the “Nothing but Snow” mission, where fighter jet is shot down and crash lands, S-SW of Himarvet.
Bootie’s example is at Tärnboda skans, part of the “Make Some Noise” mission, where you blew up the guard shack.