I caught a rare Tiny Twister shortly after WoW came back online after its weekly maintenance. The whole area was entirely repopulated, and there were at least 10 Tiny Twisters spawned. My rare popped after clearing about half of them, and some of the added pets were rares as well.
tl;dr - check for Twisters immediately after weekly maintenance.
1347 pets
I caught a rare Tiny Twister shortly after WoW came back online after its weekly maintenance. The whole area was entirely repopulated, and there were at least 10 Tiny Twisters spawned. My rare popped after clearing about half of them, and some of the added pets were rares as well.
tl;dr - check for Twisters immediately after weekly maintenance.