bark, roar, get angry
咆 centers on a loud, forceful vocal outburst: the deep bark of an animal, a roar, or a human shout of anger.
咆 combines 口 (mouth) with 包, which likely contributes the sound and suggests a contained burst of sound from the mouth.
A mouth 口 that wraps around a sound like a package 包 before releasing it: that is a bark or roar.
For ホウ, imagine a lion letting out a huge roar that echoes like a deep 'hoe' sound: hoe -> ホウ, and the mouth 口 unleashes it.