Heavy 'Mammary Clouds' Form at Sunset During Storms in Tulsa, Oklahoma

Heavy mammatus – or ‘mammary’ – clouds were seen over Tulsa, Oklahoma, on April 28 after a severe tornado-warned storm swept through the city and surrounding counties.

In this video, the cloud formation – made up of bulges or pouches at the base of other clouds – can be seen covering the sky at sunset. The clouds are said to form as a result of air turbulence within large cumulonimbus structures.

The National Weather Service issued a tornado warning for the city and nearby areas on the Tuesday evening. Heavy bouts of hail and lightning were also seen in Tulsa on the same date.

The NWS lifted the tornado warning for Tulsa at 6.45pm. Credit: RJ Goodeyon via Storyful