A long, tubular cloud that appears to roll about a horizontal axis. Often forms along the leading edge of a storm front or gust front. Indicates a change in wind direction and can precede severe ...

So what are mammatus clouds? And what do they signal is coming? Mammatus clouds often form on the base of storm clouds but can be associated with other types of clouds as well. NOAA describes them ...

"It's the downdraft or that cooler rush of air spreading outward from the storm." AccuWeather says most false tornado and false funnel cloud reports are associated with shelf clouds. "Usually ...