Menacing, adjective: suggesting the presence of danger; threatening.
Rampant, adjective: (especially of something unwelcome or unpleasant) flourishing or spreading unchecked, (of a person or activity) violent or unrestrained in action or performance, (of a plant) lush in growth; luxuriant.
Unravel, verb: undo (twisted, knitted, or woven threads), unwind (something wrapped around another object), investigate and solve or explain (something complicated or puzzling), begin to fail or collapse.
Menacing clouds, dark and ominous
The fun travel day viewing scenery
Began to unravel bit by bit
The weather turning from sunny to cloudy
We began to despair
Our travels would end in crashing rain
But the wind weaved its spell
And blew the storm away
We continued happily on our way
©Sheilagh Lee August 26, 2015