Sorry, but I think I got it now little late but is better late then never
I don't think the bug is when program generate wind bigger then 15m/s. 15m/s it is modrate strong (moderate gale not a storm) wind on sea, so for me is strange the game wind scale finish on this 15. If you programming you exacly know what you want to do, so they must know the algorithm produce numbers from 0 to 30. It is more logic for me to produce winds between 0-30m/s then 0-15m/s, specialy for u-boats game, where most patrols have a place on north atlantic. For me this strange 15m/s barrier looks very, very strange like abandoned project or rush in developing.
Where are this hevy storms described by u-boat crews, where peolpe in the machine room was shooted in the "air" by waves. I think bigest problem is in weather change period (as I said before few days with fog), and another in wind 0m/s, which is imposible rare phenomena on north atlantic.