An Examination of High Impact Severe Weather Events in the Mid-Atlantic Region

Storm Prediction Center storm reports were used to build a general severe weather climatology and to identify events which had elongated reports of severe weather in the Mid-Atlantic Region. Many of the larger elongated events were associated with meteorologically significant derecho events. However, a smaller subset of these events was associated with severe thunderstorms which produced more localized areas of linear or elongated reports of severe weather.

Several of these more localized events were examined using radar data. Initial radar data indicate that outflows associated with these events propagated from west to east producing linear or elongated swaths of severe weather. It is believed these events occur in areas where high downdraft CAPE may contribute to the production of cold pools allowing these systems to maintain tracks of 10s to 100s of kilometers. When these smaller spear-head echoes develop, they produce a significant amount of severe weather over a region. Recognizing these echoes early can help forecasters improve warning decisions. Several examples using radar will be used to illustrate the scale of these features and how they can account for a significant number of severe reports on any given day.

A general annual climatology of severe weather will be presented along with examples of these more localized, concentrated severe events. These regional events share many characteristics of derechos but are too short-lived to meet the criteria of a derecho. Comparative derecho events will also be presented.