"CraigT" writes:

The more I stare at this the more I think it was a lightning strike.

Notice the wrinkles in the Tyvek correspond to the indents of the siding.
Yes the heat source was outside, melted the siding, and where it touched the
Tyvek it distorted/melted it too.

No way.

Lightning would make a hole. Not heat the siding to melting point.