Okay guys, after a great deal of further investigation, I think I may have finally made something of a breakthrough. First, a question:
What would tie Boston Harbor to the Glowing Sea, radiation storms, a 2285 start date, the design of vault 111, and the start of the great war? Well, you may wan't to consider the following:
On the morning of 23rd October 2077, a Chinese Super-Sub (seen https://youtu.be/D5esyZPt5Jo?t=4m27s at 4:27, current Chinese flag shown https://upload.wikimedia.org/wikipedia/commons/thumb/f/fa/Flag_of_the_People) drifts into Boston Harbor after a 'mechanical failure'. The sub begins to descend, and eventually collides with a https://en.wikipedia.org/wiki/Submarine_mines_in_United_States_harbor_defense (shown https://youtu.be/D5esyZPt5Jo?t=3m40s at 3:40 on the right-hand side of the 'green' image). The detonation partially ruptures the hull, and a distress signal is immediately sent out. When the sub hits the bottom of the harbor, the resulting impact kills most of the remaining crew members, and also causes damage to the area surrounding the reactor core.
Meanwhile, the scrambled distress signal is received by the Chinese Military, and when contact with the sub is lost, it is assumed that this was a deliberate strike by the US. And so a non-nuclear missile is launched on an American target in retaliation, most likely another sub or a https://en.wikipedia.org/wiki/Destroyer. The US Military sees this as an act of war, and so they also retaliate. Before long, the situation escalates, and the result is a full-scale nuclear exchange involving China, the US, and the USSR.
Three nuclear warheads detonate in the Greater Boston area. First in Lincoln (seen from vault 111), then in Prospect Hill, and finally, in the harbor between the Boston Harbor Hotel and the airport. The detonation in the harbor throws up a massive volume of mud, water, and other debris at supersonic speed, destroying and partially vaporising many of the nearby buildings as seen in the foreground of https://www.youtube.com/watch?v=D5esyZPt5Jo&feature=youtu.be&t=4m45s image at 4:45. The underwater detonation also sends out a powerful electromagnetic pulse, causing http://navyadvancement.tpub.com/14325/css/14325_370.htm to the electrical systems inside the sub. The shockwave also tears a http://www.extremescience.com/deep-sea-vents.htm along the sea-bed, and the submarine ends up lodged partway down the fissure, leaking dangerous levels of radiation into the surrounding water.
The result of this incident is a https://en.wikipedia.org/wiki/Hydrothermal_vent on the sea-bed, which contains high levels of radiation (due to the ruptured core of the sub's nuclear reactor), a large pocket of superheated water, and a submarine hull that has been charged up like an enormous electromagnet by the EMP blast, and maintained by the reactor core. Whenever the temperature reaches a critical point, electrostatically charged and highly irradiated water is pushed up towards the surface, causing the surrounding water to 'glow'. The water vaporises as soon as it reaches surface level, and this vapour quickly gathers at high altitude to form electrostatic irradiated clouds. The clouds are blown inland, and as they move, radioactive lightning bolts are discharged, as described by Todd during the interview following the showcase.
As for the 2285 start date, an 8 year duration would allow more than enough time for the technology from project purity to be brought to other areas along the East Coast, including New York and the Commonwealth. This would explain the relatively 'clean' water we have seen in the showcase and concept art (apart, of course, from the radiated water being produced inside the hydrothermal vent).
And finally, the design of vault 111, as suggested in http://www.gamesas.com/topic/1523172-is-vault-111-built-like-a-submarine thread, now seems even more viable, as it ties in very closely with the incident described above.