Cloud suck The telltale signs for a pilot climbing in the thermal under a "sucking" cloud are (1) lift strengthening, (2) lift getting smoother, and (3) widening of the thermal. Paraglider pilots have reported being unable to descend in strong cloud suck, even after bringing their canopies into deep spiral, which would normally result in a rapid vertical descent. Cloud suck is especially dangerous for paraglider pilots, whose maximum speed is less than 30 knots, because storm clouds (Cumulonimbus) can expand and develop rapidly over a large area with accompanying large areas of strong lift. On 14 February 2007 while practising for
Tornado outbreak of May 15–17, 2013 severe thunderstorms early that morning over northwestern Texas, for a threat of large hail and damaging winds. A low-pressure area associated with the trough moved over Oklahoma that day, producing light to moderate rainfall and non-severe thunderstorms across that state into parts of North Texas. Later forecasts expanded the slight risk further into northern and central Texas, and later into far southern Oklahoma, and indicated an enhanced risk of a few isolated tornadoes in north Texas. The atmosphere began to destabilize due to a decrease in cloud cover over western and central Texas; the sunshine and heating, combined with sufficient