ESS124
Prof.
Jin-Yi Yu
Flooding from Mesoscale
Convective Systems – Squall Line
•Thunderstorms organized as either frontal squall lines or mesoscale convective systems (MCSs) most commonly generate floods between Rocky Mountains and the Appalachian mountains.
•Flash floods associated with frontal squall lines occur when the frontal boundary is nearly stationary and the winds, both at the surface and aloft, flow essentially parallel to the front.
•Individual thunderstorm cells move along the front producing rain over the same location in a process called training, similar to boxcars of a train pass over
the same
location along the front.
A flood occurred on 13-14 August 1987.