Figure 1 depicts the surface observations at 8:00 am EDT, which shows a cold front moving south-southeast across southern Ontario. This front eventually reached Massachusetts and triggered thunderstorms, which ultimately led to this tornado.
The Lexington, MA F0 tornado of July 18, 1983 impacted Middlesex County in Massachusetts. According to NOAA (2019), the F0 tornado caused no fatalities or injuries, but caused $250 dollars in property damage. The tornado touched down near Hancock Street at 4:30 pm EDT. The tornado travelled for 0.4 miles and had a maximum width of 20 yards.
NOAA Central Library. (2020). U.S. Daily Weather Maps. Monday July 18, 1983 [PDF]. Retrieved from https://library.noaa.gov/Collections/Digital-Collections/US-Daily-Weather-Maps
NOAA National Centers for Environmental Information (2019). Storm Events Database. Retrieved from: https://www.ncdc.noaa.gov/stormevents/