Nothing but the rain

Over the course of their friendship, Galactica commander William Adama and Viper pilot Kara "Starbuck" Thrace have a greeting they share on occasion. The greeting appears to have little meaning except between the two pilots.

Adama greets Thrace with the saying as she jogs through the battlestar's corridors (Miniseries, Night 1).

Some hours later, while zealously defending Lee "Apollo" Adama's cripped Viper from the horde of Raiders at the Battle of Ragnar Anchorage, then-Commander Adama breaks Starbuck's fighting trance over wireless communications with their greeting to call her back to the battlestar, which had committed itself to an imminent jump. The debris of destroyed Raiders made raining noises as they impacted Starbuck's Viper (Miniseries, Night 2)

Over a year later, a distracted Thrace walks past Admiral Adama and President Laura Roslin, oblivious to their presence, when Adama uses their greeting once more to get Thrace's attention. It would be the last time Adama and Thrace would use their greeting before her demise (Maelstrom).

The greeting was generally consistent except for Thrace's last line, which was generally an acknowledgement ("Wilco" or "Aye-aye, sir!") that she tends to improvise.

Adama: Starbuck, what do you hear?

Starbuck: Nothing but the rain.

Adama: Then grab your gun and bring in the cat.

Starbuck: Boom, boom, boom!