A 15-year climatology of derecho producing mesoscale convective systems over the Central and Eastern United States
Abstract
A 15 yr (1986–2000) climatology of derecho-producing mesoscale convective systems
(DMCSs) is presented in order to better delineate their spatial and temporal patterns. Several significant
results emerged from the analysis, including the development of the NW flow corridor as the
dominant derecho activity region in the climatology. Results suggest that, as the sample size of
DMCSs increases (230 events), the prominent derecho activity corridors across the eastern US
become located in the northern Plains through the Ohio Valley, with a secondary maximum in the
southern Plains. Evidence further suggests that climatological factors strongly control the distribution
of derechos. For example, an anomalously strong 500 hPa height gradient existed coincident with the
northern US derecho activity corridor. Another aspect of derecho development is related to the
temporal distribution. Evidence suggests that derecho systems tend to occur in groups or ‘families’,
several events occurring within several days. The synoptic environment also appears to be responsible
for activating these corridors and providing an environment conducive to DMCS grouping.