Storm spotters will look for a low, rain-free cloud base around that area, which is called a wall cloud
. If this cloud is rotating, it's possible a tornado may be produced.
An ominous looking orange-brown wall cloud
filled the western horizon.
The chaser, air- or ground-borne, intercepts the storm after the wall cloud
, the rain, hail and massive winds have passed.
"It was about two miles south of Highway 98 when I saw the wall cloud
front of me."
Those in the audience learned what to look for in a rare supercell thunderstorm like the one that spawned last June's tornado, which usually features a wall cloud
, which can produce a tornado, and a shelf cloud that precedes a squall line like the one that scared people in town a week later.
By the time I climbed into the camper, a wall cloud
was fast approaching.