A Synoptic Climatology of Derecho Producing Mesoscale Convective Systems: 1986-1995

In 1888, Iowa weather researcher Gustavus Hinrichs gave widespread convectively induced windstorms the name derecho. A derecho includes any family of downburst clusters with temporal and spatial continuity and a major axis length of at least 400 km. Derechos are produced by mesoscale convective systems (MCSs) and occur throughout the Plains and eastern United States.

To date, a synoptic climatology of the derecho has not been performed. Insights, through individual case studies, have been made into favorable derecho producing environments. However, synoptic conditions conducive to derecho formation and propagation have not been determined.

Specific aims of this investigation are:

1) To document and map, both annually and seasonally, a 10 year record of derechos, covering the central and eastern United States.

2) Determine synoptic conditions favorable for the development of derecho producing MCSs.

3) Develop a regionalized pattern/diagnosis technique for recognizing synoptic-scale weather patterns favorable for derecho producing MCSs.

By performing this investigation, several advancements in derecho/MCS research are made. First, a better understanding of where these systems form, move and dissipate is gained from determining the spatial and temporal distribution of these events. Secondly, this investigation will not only be the first climatology of derecho producing MCSs, but also the first to examine synoptic-scale features common to derechos that occur outside of the warm season (May through August).