The transport of heat and moisture by the movement of a fluid; In meteorology, the term is used specifically to describe vertical transport of heat and moisture in the atmosphere, especially by updrafts and downdrafts in an unstable atmosphere. Cumulonimbus, towering cumulus clouds and alto-cumulus castellanus clouds are all visible forms of convection. Convection is [...]
A forecast containing the area(s) of expected thunderstorm occurrence and expected severity over the contiguous United States, issued several times daily by the SPC. The terms marginal, slight risk, enhanced risk, moderate risk, and high risk are used to describe severe thunderstorm potential. Local versions sometimes are prepared by local NWS offices.
Tending to move toward one point or to approach each other. Convergence in a horizontal wind field indicates that more air is entering a given area than is leaving at that level. Convergence at low levels may result in upward forcing; at higher levels convergence may result in downward forcing. When other factors such as [...]