What in the world was that cloud spotted in Alabama on Tuesday?

A picturesque undular bore cloud was seen across Central Alabama Tuesday morning
A great undular bore cloud was spotted across Central Alabama on Tuesday.
A great undular bore cloud was spotted across Central Alabama on Tuesday.(WSFA 12 News/NWS Birmingham)
Updated: Aug. 12, 2020 at 7:33 AM CDT
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MONTGOMERY, Ala. (WSFA) - There were some odd-looking clouds spotted across parts of Central Alabama early Tuesday morning. Not only were they spotted on satellite, but several folks up near the Birmingham Metro were able to actually photograph them.

Some of the pictures posted to social media really stood out.

So what exactly are we seeing here?

They are referred to as undular bore clouds. Yes, you read that right. They are a real thing, and that is their actual scientific name. Undular bores are waves in the atmosphere that can be seen on radar. They can also sometimes be seen by the clouds they end up producing.

That was the case Tuesday morning north of Montgomery.

They showed up nicely on visible satellite; you can see what appear to be thin lines propagating southward in the satellite loop above. Those are the undular bores.

According to the National Weather Service in St. Louis, “They form when an air mass, such as a storm outflow boundary, collides with another air mass characterized by cool, stable air.”

That’s exactly what happened Tuesday morning. Rising air parcels on the leading edge of an outflow boundary from storms that formed north of I-20 met up with more stable air around the Birmingham area. Once that occurred, the air parcels sank, thus forming the wave-like pattern many folks observed.

“These are actually more frequent than you’d think, but just not as noticeable. Most of the time they’re only visible on radar from non-meteorological scatterers (bugs, dust, etc.). Seeing it this pronounced visibly is fairly rare.”

That’s what the NWS in Birmingham had to say regarding the rarity of undular bores. They aren’t necessarily super rare, but capturing them certainly is.

That is especially true because the undular bores we get here in Alabama typically develop during the middle of night and linger into the early morning hours as thunderstorm complexes fizzle out and send outflow boundaries across the state.

So if you ever see clouds like the ones pictured above, consider yourself lucky!

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