Apparently. My marksmen have a track record for flashing past it.
Goes like this: Ahh! The enemy jungler! walks toward tower Thresh, why are you at tower? Help me! Walks past a bright green blue lantern with easy access Ehh. Must I, the AD Carry, do everything myself? Flashes Jungler/support's CC catches marksmen and dies
Actual context. I pay attention to the map very well. And I ward a lot. I throw the lantern usually in a good spot (At times I throw it where minions are and I slap my head when I do because I panicked) and the marksman flashes PAST the lantern.
What is intresting is that there are times 1 of the 3 enemies (Markman, support or jungler) stop chasing after I am safe and throw the lantern but then realizes, hey, my marksmen flashed past it.