Mesocyclone seen on MegaDoppler 13

A small, but powerful, counter-clockwise spinning thunderstorm moved right over Houston Wednesday afternoon. The circulation only lasted a few minutes. No warning was issued and no severe weather was reported. But the view in the sky and on the radar was quite ominous.

The image to the left is a screen capture from our own MegaDoppler13 HD. The small hook echo developed at 1:57 PM. By 2:02 PM the circulation was wrapped in rain and the storm weakened. The thunderstorm was drifting to the west which, interestingly, puts this hook at the leading edge. The hook echo usually appears on the trailing edge of a supercell.

A shear marker popped up on this storm for exactly 2 minutes which indicates a lock on the low-level and mid-level rotation.

We also saw the storm pass by our TowerCam. You can see a lowering of the cloud base in the screen capture to the right. (The height of the camera makes the storm appear closer than it really is.)  The view from the TowerCam matches what we were seeing on MegaDoppler 13.

You can watch a timelapse video of the storm here.

Mesocyclones form in the updrafts of strong thunderstorms. Although tornadoes can form in these types of storms, a study in the late 1990s revealed less than 25% of mesocyclones produce tornadoes. I think today's storm weakened because the circulation was at the front of the storm. The rain falling out of the storm cut off the inflow which disrupted the circulation after a few minutes.

Comments

[Justen Simpton]

The Pearland meso and funnel formed in front of the storm also. Both of these mesos were produced mainly from a rapid imbalance of outflow and inflow. A low pressure draft vacuum.