WATCH: Ominous storm cloud engulfs Vancouver Friday evening

VANCOUVER, Wash. (KOIN) -- Stormy skies quickly raced over downtown Portland and took aim at Vancouver Friday evening.

A dark and ominous storm cloud quickly raced north across the Willamette Valley before soaking Vancouver with beneficial rain. Portland has already surpassed its average monthly rainfall for August in part due to Friday's wet weather.

This dark storm cloud that moved over Vancouver is known as a 'shelf cloud'. That's when heavy rain pulls cool air...