Thunderstorm Morphologies with Mountain Interactions in New England

A previous climatology on topographical influence on thunderstorms in eastern New York and western New England concluded that underlying terrain affects the location of thunderstorms. Another study has demonstrated changes in intensity of linear convective systems in the White Mountains. The goal of this study is to identify shifts in thunderstorm morphologies when they interact with mountains and investigate how the storm environment changes. This analysis investigated five (2011 – 2015) warm season (April - September) thunderstorm days in New England. Using archived METARs from the Iowa State Mesonet archive, thunderstorm days were identified if the reports contained LTG (lightning), LTG DSNT (distant lightning), or TS (thunderstorm) codes. NEXRAD Radar reflectivity data from NCEI was used to subjectively identify thunderstorm morphologies based on Gallus et al. (2002). RUC hourly analyses were used to collect sounding parameters from the storm environment using coordinates from the leading edge of the storm.

Results found that shifts in storm morphology were least frequent in the White Mountains (~18%) while shifts over the Green Mountains were most frequent (~56%). Analysis of the storm environments show that the Green Mountains have a significant amount of instability (lower average LI) compared to the other mountains. RUC storm motion data shows that on average over the Berkshires storms move quickly and have a southerly component while storms over the Green and White Mountains have a northerly component of motion. However, the Berkshires have lower average precipitable water values to sustain such storms.