SERIAL DERECHO
A serial
derecho event (hatched area) typically is associated with an extensive squall
line or "quasi-linear convective system" (dashed / double-dotted line) with multiple embedded bow echoes. Within
the squall line, the bow echoes may be of widely varying sizes. Serial derechos
usually occur in conjunction with well-defined, migratory low pressure
system.
PROGRESSIVE DERECHO
A
progressive derecho event (hatched area) typically is associated with a squall
line of restricted length that may involve
a single bow echo or multiple bows. Progressive derechos usually are
associated with a stationary front in a rather stagnant large scale weather pattern.