A Climatological Study of Linear Convective Systems in Northern New England

Linear convective systems (LCS) over northern New England were classified for 5 warm seasons (April-September 2003-2007) using 0.5 degree base reflectivity radar data for the Gray, Maine (KGYX) radar domain. This classification was used to develop a climatology of LCS mountain interactions. The LCS were identified by their structure, following the method of Lombardo and Colle, into: broken lines, bow echos, lines with no stratiform precipitation, lines with leading stratiform precipitation, lines with trailing stratiform precipitation, lines with parallel stratiform precipitation, and an additional classification for this study, miscellaneous structures. Lines were then categorized by their interaction with the mountain ranges within the KGYX radar domain, specifically the White and Ossipee Mountains of New Hampshire, and the Longfellow Mountains of Maine. The interaction types were increasing intensity, decreasing intensity, no change in intensity, dissipating entirely, or dissipating and then reforming downstream of the mountains. Prevailing 700 hPa flow was identified to determine if the storm intensity was affected by prevailing wind direction. The purpose of this study was to: 1) determine if a previous classification system developed for the Midwest could be used in complex, mountainous terrain; 2) create a climatology of LCS mountain interactions; and 3) determine the factors driving the interactions. No correlation was found between prevailing flow and mountain interaction. One interesting discovery was that in southwest flow storms tended to increase intensity only slightly less often than they dissipated entirely, with other interactions being statistically insignificant. Two case studies were completed to determine what other factors most likely had the strongest impact on the LCS interaction with the mountains for both southwest flow increasing intensity and southwest flow dissipating entirely.