PITTSBURGH (KDKA) – While clouds are nothing new to Western Pennsylvania, some pretty rare clouds were spotted over the Turnpike.

KDKA viewer Ken Jones captured a photo of rare wave-shaped clouds that he saw over the Turnpike on the way to Philadelphia.

(Photo Credit: Ken Jones)

KDKA meteorologist Ray Petelin says these are Kelvin-Helmholtz clouds, “a very rare cloud pattern that is caused by velocity shear.”

“Velocity shear occurs when winds are traveling at different speeds at different heights in the atmosphere.”

“In the case of these cloud patterns, the winds are moving faster at the top of the cloud, than the winds at the bottom of the cloud, just like how waves are created on water. While these cloud patterns are very rare, the most often occur when it is windy.”

And winds are now on the way, with a Wind Advisory issued for much of Western Pennsylvania from 10 a.m. Wednesday through 7 a.m. Thursday. Parts of Ohio and West Virginia are also under the advisory.