Complete the dramatic weather reporter's live broadcast.

"Grab your umbrellas and hold onto your hats, folks! _____ pouring rain outside, and the wind is howling!"

The correct answer is It's.

When talking about the weather, we use it is (or the contraction it's). "There's" is used to say something exists, but for weather conditions like raining or snowing, "it" is the perfect impersonal subject.