Yes, TROPICAL is a Scrabble word!

Letter values in Scrabble US: T 1, R 1, O 1, P 3, I 1, C 3, A 1, L 1.

Is it a valid word?

TROPICAL is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

relating to or situated in or characteristic of the tropics (the region on either side of the equator)
of or relating to the tropics, or either tropic
characterized by or of the nature of a trope or tropes; changed from its literal sense
of weather or climate; hot and humid as in the tropics