Hoosiers are clamoring about an interesting cloud formation that crept through central Indiana Saturday morning.
“… a weak boundary formed from the ‘rain-cooled air’ aloft and brought a very cool cloud formation for Hendricks/ Boone counties. It is known as an undular bore cloud or roll cloud. There were reports of gusty winds along the strange-looking cloud as it approached Marion County” said Amber Hardwick in her Saturday morning weather blog.
The National Weather Service defines an undular bore as “a wave or waves in the atmosphere that can be seen on radar and sometimes by the clouds they produce. They form when an air mass, such as a storm outflow boundary, collides with another air mass characterized by cool, stable air.”
— Angela Ganote (@angelaganote) September 28, 2019
Meteorologist John Dissauer said that while undular bore clouds are not uncommon, the timing of Saturday morning’s cloud formation may have contributed to more people noticing it.