Al flushed ever so slightly as he realized that this woman wasn't a witch. Which meant she must be a Muggle, and he had just used magic in front of her. "Oh, blimey," he muttered, moving to return his wand to his pocket. He hesitated for a second and decided since she'd already seen one spell, she might as well see another. So with another flick of his wrist, he stated, "Impervius."
There. That would keep the water from soaking him to the bone, at least. Then he returned his wand and wondered, idly, how long before the Ministry showed up to confiscate it for having broken the cardinal rule of the wizarding world.
"America?" he repeated, hoping that maybe steering the conversation back to what she had said would keep her from mentioning the fact that he was a wizard. He thought it a bit odd that she wasn't reacting as most Muggles might, but really considering the night he was having, a bit odd was much better than the outright bizarre situation he'd found himself in.
"I don't... this isn't possible," he shook his head as her words finally sank in. "I can't be in America. It just isn't possible." Except clearly, it was. With a frustrated sigh, he muttered as he glanced around, "If my brother had anything to do with this, I'll hex him but good."
Then, suddenly remembering his manners, Al's eyes widened as he looked back to the woman. "I'm sorry, I'm being terribly rude. My name is Al. Al Potter." He extended his hand for her to shake, as was the polite thing to do, as he waited for her reply.