Figure 1 depicts the surface observations at 8:00 am EDT, which shows a cold front moving across the northeastern United States. This front became the focus for thunderstorms, which ultimately led to this tornado.

The West Sterling, MA F3 tornado of October 3 , 1970 impacted Worcester and Middlesex counties in Massachusetts. According to NOAA (2019), the F3 tornado caused no injuries, but caused one fatality and caused $500 thousand dollars in property damage. The tornado touched down near Furnace, MA at 6:15 pm EDT. The tornado travelled for 35.4 miles and had a maximum width of 60 yards.
Sources
NOAA Central Library. (2019). U.S. Daily Weather Maps. Saturday October 3, 1970 [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/