Marine Thunderstorm Wind — Coastal Waters From Provincetown Ma To Chatham Ma To Nantucket Ma Out 20 Nm Values, Atlantic North

2019-07-23 · near Chatham Light, Coastal Waters From Provincetown Ma To Chatham Ma To Nantucket Ma Out 20 Nm Values, Atlantic North

Event narrative

High sustained winds of 62 mph were measured by a mesonet site at Chatham.

Wider weather episode

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.

View location on OpenStreetMap → (41.6700, -69.9500)

Source: NOAA Storm Events Database, event_id 846489. Narrative written by the NWS forecast office that issued the report.