Diversion
The way i have been taught to do it if am in controlled airspace is 'Approach/whoever, Diverting to C due to weather request climbing/descending to/maintaining FL/altitude xxx estimating C at time xxxx'. This call to me is a complete one since remember when diverting you must plan new altitude to clear new obstacles that you never take into account in your original planning. Remember also this is like planning from scratch for this leg, so you need time estimate as well. Thanx guys