What is the adjectival form of "turmoil"?
As simchona said, there is no adjective derived from turmoil, nor any adjective with a related etymology. So in the strict sense, there is no adjective form of the word turmoil.
For a word with the appropriate meaning, I would suggest tumultuous:
(adj) disruptive, riotous, troubled, tumultuous, turbulent (characterized by unrest or disorder or insubordination) "effects of the struggle will be violent and disruptive"; "riotous times"; "these troubled areas"; "the tumultuous years of his administration"; "a turbulent and unruly childhood"
Source
Having checked the Oxford English Dictionary for turmoil, it turns out that it is derived from the Old French tremouille or mill-hopper. However, while there are both noun and verb forms of turmoil, there is no adjective which shares that etymology. So, I suggest turbid:
not clear or transparent because of stirred-up sediment or the like; clouded; opaque; obscured: the turbid waters near the waterfall.
thick or dense, as smoke or clouds.
confused; muddled; disturbed.