Figure 1 depicts the surface observations at 5:00 pm EDT, which shows a stationary front across the northeastern United States and an area of low pressure sitting just north of Massachusetts. This area of low pressure and interactions with the stationary front caused thunderstorms to develop in the afternoon hours of August 20th across western Massachusetts, which ultimately led to this tornado.
The Pittsfield, MA F0 tornado of August 20, 2004 impacted Berkshire County in Massachusetts. According to NOAA (2019), the F0 tornado caused no fatalities or injuries, but caused $25 thousand dollars in property damage. The tornado touched down near Fenn Street at 6:37 pm EDT. The tornado travelled for 1 mile and had a maximum width of 150 yards.
Sources
NWS Weather Prediction Center Surface Analysis Archive. (2017). Surface analysis 21Z Fri Aug 20 2004. Retrieved from: https://www.wpc.ncep.noaa.gov/archives/web_pages/sfc/sfc_archive.php
NOAA National Centers for Environmental Information (2020). Storm Events Database. Retrieved from: https://www.ncdc.noaa.gov/stormevents/