Mammatus As Storm Passes Through

Jul 5, 2004
New Jersey
I had forgotten to mention this before-but about a couple of weeks ago, some strong thunderstorms came through my area. Where I live, one rather ominous cloud passed on through-no lightning or thunder. There was blue sky behind this cloud-it was moving west to east. As I looked at the cloud, I noticed some mammatus formations, not far from the westernmost edge.

So-is this fairly common? Where do you usually see mammatus-before or after a storm moves through? :blink:
Mammatus form on the underside of the anvil - thus often at a relatively high altitude although they can be a bit deceiving and look lower. As they are attached to the storm itself, they will follow its motion (often W>E as you described).

You can see them before or after a storm, but in my observations, I have normally observed them following a storm passage. Mammatus is frequently very photogenic, in my experience. There are many spectacular photos of mammatus being lit from beneath by a setting sun.

I can't post the image because it is a .png, but click the link below and you'll see where mammatus can occur in a generalized diagram.