Help with timezone conversion!

I have the following function:

	public function getSlotTimeFromAMPM() {
		return date('h:i a',strtotime(slot::$slotQry["slot_time_from"]));

The problem is these times are stored in a timezone based on the user that created it. (I.E. America/New_York). However, I need to automatically convert that time from the base timezone to the user that is logged in. (I.E. America/Los_Angeles).

Any ideas?