I don't remember exactly, but Tstorms have brought airliners down in the past, easy to google I suppose. In my heqad I most usually associate fatal aviation thunderstorm encounters by crews flying directly into them by flying into a radar shadow.
There is also the issue of the "contour hole", where very heavy precip in a cell can result in no radar return, giving the false impression of a hole in the storm. (I'm assuming by shadow you mean that an even worse storm is obscured by a more moderate storm in the direct path of the radar, and the crew don't realize they were in trouble until it's too late.)
Recall the Southern Airways DC-9, which was lost when flying in bad weather over Georgia, in 1977. The aircraft CVR recorded the captain as saying "Looks heavy - nothing's going through that", but only a few minutes later, they flew into the most intense part of the storm.
The only explanation the NTSB came up with was that since the aircraft was already flying through heavy precipitation, the captain misinterpreted a contour hole on their x-band radar as being an area free of precipitation, and headed for it. The captain's comment that things were "all clear left" seems to confirm that explanation. The aircraft altered course to the left at that point, right into the worst part of the storm.