National Weather Service United States Department of Commerce

Widespread Showers Across the Eastern Half of the US; Severe Thunderstorms in Montana into the Plains

Widespread coverage of showers and thunderstorms across much of the central and eastern U.S., will produce areas of excessive rain in the northwest Gulf Coast, portions of the Mississippi Valley and the southern Mid-Atlantic states. Scattered severe thunderstorms are expected from Montana into portions of the central/southern Plains this weekend. Read More >

Shelf clouds are often associated with squall lines, and many times they are reported as wall clouds, funnel clouds, or rotation. Below is a brief review of what a shelf cloud, wall cloud, and funnel cloud look like. Remember, that the main threat with any squall line is severe damaging winds associated with the shelf cloud, although brief spin-up tornadoes can occur. Often times, these tornadoes are rain-wrapped and short-lived.

A shelf cloud will usually be associated with a solid line of storms. The wind will come first with rain following behind it. It may appear to rotate on a horizontal axis.

 

Crawford County wall cloud

Wall clouds will rotate on a vertical axis, sometimes strongly. The wall cloud is much smaller and more compact than a shelf cloud and is usually under a rain free cloud base.

 

Scud clouds are often mistakenly called wall clouds or funnel clouds. In reality, these are just rising clouds due to increased low level relative humidity. They will not rotate and will rise slowly.