Touche', Ratty!
Have seen it literally dozens of times in Herks - typically starts on the wipers & may be blue, green, or even red in colour, but blue is by far the most common (of course, on NVGs, it's all green!
)
We have static strips on the nose of our MC-130H - look a bit like zippers - often see streaks of it along there long before anywhere else since they installed those (last 4-5 years for the new radomes).
Have had the good fortune to not be struck by lightning after experiencing St. Elmo's Fire (knock wood) and have seen it not associated with CBs - ie. in the clear or just stratus clouds, but rare - usually CBs are near.
Have seen it dance on the tips of the pitot tubes, prop spinners, & have it make very symmetrical lines along the windscreen repeatedly (like veins of a leaf), but mainly on the wipers (and nose for the MC-130H).
As stated, nearly always accompanied by static on radios.
Typically, we'll try to change level or course if it persists longer than a couple minutes as it has been documented to precede lightning strikes.
Have heard stories of "ball lightning" entering the cabin & rolling through the cargo compartment - this from a much older C-141 mate.