Possible Clues:

• Precipitation that can be golf ball-sized
• Frozen rain; call taxi
• This comes down hard by way of greeting
• Hard to be coming down and be so welcome
• When repeated, exuberant cry
• Sing the praises of Hard Rain?
• This salutation sounds robust
• '___ Caesar!'
• Greet — bad weather
• Sounds a fit way to greet someone really popular