Thunderstorm Wind in Barnstable County, Massachusetts

A NWS survey team determined that although a weak, shallow waterspout was observed over the southern end of the Bass River, the damage observed in West Dennis was from straight-line microburst winds, estimated at 90+ mph. Media and amateur radio contributed to the following reports, as well. Numerous trees and wires were snapped or downed at Wrinkle Point. Trees and wires were down on Loring Avenue. Wires were down on Corporation Road. Trees, wires, and a utility pole were down on Pleasant Street. Wires were down on a car on Depot Street at Vester Drive. Power lines were down on Old Wharf Road. Trees down on Sunset Drive. There were many others. State Emergency Management reported that the cost to Dennis just for cleaning up the roads was a whopping $860,000. Total estimates were approximately triple that figure, when accounting for individual homeowner and business claims.

A deep southerly flow of tropical moisture was in place over southeast MA with precipitable water values in excess of 2 inches on the south coast. A frontal wave along the coast provided strong low level convergence and that combined with upper divergence from the right entrance region of a 110 knot upper level jet to produce very severe weather for Cape Cod. Three tornadoes occurred! Prior to these, there had only been three recorded tornadoes since 1950. Outside of the tornado area, damage surveys showed that strong microburst winds caused straight-line damage.