The Watcher and the Balrog were probably under Morgoth's direct command, and later fancied ruling their own little areas after learning that Morgoth would never come back. Sauron was like that in Mordor, until he decided to conquer the East and beat the West.

Sauron can 'torture' the very hills, according to Amroth. He may somehow be poking and prodding Caradhas like one would a raging bull on a chain-the ones closest to the chain (The Walkers) get gored, so to speak. I think Sauron used a bit of his Aulean stone-lore to do such a thing, or projected his mind through his Palantir to annoy the Balrog, which in turn annoyed Caradhas.

My preferred UUT is that he told the WitchKing to do it-if only to stop Gandalf from moving and not to regain the Ring. The WitchKing , in the Appendices is said to be able to create snowstorms and evil winds by the Lossoth, who say that in summer, his power weakens somewhat. Sauron is a sorcerer himself, as well.

There is but one task remaining in Arda-we,the Dragons of Valinor will make it happen.

Lone resident of the Republic of Gondor

PO-TA-TOE-S not PO -TAH-TOE-S!