KanjiJLPT N2
Overnight

overnight stay, put up at, ride at anchor

Mnemonic

A violent storm paints the world white with blinding snow. You pull off the road and check into an inn to stay overnight. Through the frosted window, you watch white flakes spiral in the storm's fury until dawn.
Additional thoughts
Water (storm) + white = staying overnight. Picture the white-out conditions of a snowstorm forcing you to lodge somewhere. The white snow and raging storm trap you for the night.
Quick recall
A storm of white snow forces you to stay overnight at an inn.

Details

The keyword for 泊 is overnight. This kanji refers to the act of staying somewhere for the night, such as lodging at a hotel or inn. It conveys the idea of stopping one's journey to rest and sleep at a particular place. By extension, it is also used as a counter for the number of nights spent at a lodging.
On'yomi
はく
Kun'yomi
と.まる、と.める