Figure 1 depicts the surface observations at 8:00 am EDT, which shows a cold front moving across the Great Lakes. This front eventually moved across Massachusetts throughout the afternoon and triggered thunderstorms, which ultimately led to this tornado.
The Chelmsford, MA F2 tornado of July 21, 1972 impacted Middlesex County in Massachusetts. According to NOAA (2019), the F2 tornado caused no fatalities, but injured 4 people and caused $2.5 million dollars in property damage. The tornado touched down near Middlesex Road at 5:00 pm EDT. The tornado travelled for 7.6 miles and had a maximum width of 37 yards.
NOAA Central Library. (2019). U.S. Daily Weather Maps. Friday July 21, 1972 [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/