An associated low-pressure area and atmospheric instability resulted in the formation of tornadoes across northern Texas and Oklahoma on May 15.
12.
In general, funnel clouds are a result of atmospheric instability, a condition that arises when a layer of cold air overlies a layer of warm, moist air.
13.
When tropical cyclones move over land, they often produce the wind shear and atmospheric instability required for the development of weak, embedded supercell thunderstorms, which can produce tornadoes.
14.
The neutral atmospheric stability assumption discussed above is reasonable when the hourly mean wind speed at a height of 10 m exceeds 10 m / s where turbulent mixing overpowers atmospheric instability.
15.
The precipitation regime shows a sharp maximum in autumn ( September to December ), when atmospheric instability is at its highest point, medium values in winter and early spring, and lowest values from May to August.
16.
Unlike the related phenomenon associated with severe thunderstorms, cold-air funnels are generally associated with partly cloudy skies in the wake of cold fronts, where atmospheric instability and moisture is sufficient to support towering cumulus clouds but not precipitation.
17.
Atmospheric instability caused by these warm winter storm systems allows the formation of small, weak, isolated thunderstorms, which tend to move across the area quickly, producing a few rumbles of thunder, and soon dissipate back into the larger rain storm system.
18.
On January 3, the SPC issued a slight risk outlook for portions of Southeast Texas and the lower Mississippi Valley, citing the predicted passage of a shortwave trough and the potential for increasing atmospheric instability which would in turn increase the likelihood for tornadic activity.
19.
"' Cumulonimbus "', from the Latin cumulus ( " heap " ) and nimbus ( " rainstorm ", " storm cloud " ), is a dense towering vertical cloud associated with thunderstorms and atmospheric instability, forming from water vapor carried by powerful upward air currents.
20.
Although cirrus clouds " a bank of which had developed in west Texas and overspread portions of Oklahoma later in the morning " were present through much of the day, an area of clearing skies over western north Texas and southwestern Oklahoma early that afternoon allowed for the sun to heat up the moisture-laden region, creating significant atmospheric instability.
