Sunday marks 35 years since the US-Canadian Tornado Outbreak of May 31, 1985. The outbreak remains the worst on record for this part of the country, and included the only F5 tornado recorded in Pennsylvania.

21 News talked to Fred McMullen, Warning Coordination Meteorologist from the National Weather Service in Pittsburgh, about the extreme set of atmospheric conditions that led to such an outbreak.

He explained that "the cap", a thin layer of warm, dry air that usually keeps thunderstorms from developing, broke during the strong afternoon surface heating on May 31.

"If that cap had been two to four degrees Fahrenheit warmer, the day wouldn't have happened," McMullen said.

Many folks in Trumbull County that day said they had little to no warning. The county had been placed under a Severe Thunderstorm Warning based on the storm that ended up producing the Newton Falls-Niles-Wheatland tornado, but the warning was never upgraded to a tornado warning.

McMullen says technology and warning capabilities in 1985 weren't what they are now.

"In the mid-80s, most of how we received information to issue tornado warnings was from SKYWARN spotters and people calling our office."

According to the NOAA/NWS Service Assessment, a postmortem of how all local NWS offices performed during the outbreak, the SKYWARN spotter network was not activated for our area on May 31.

The assessment also says the Youngstown NWS office, having been crippled by power outages and communication failures, tried to put a verbal Tornado Warning over the Emergency Broadcast System, but did not tell the Cleveland NWS office, which had taken over warning responsibilities for Trumbull County. Therefore, Cleveland was not able to issue a formal Tornado Warning for the Niles tornado.

The assessment went on to say that local NWS offices performed well, especially given the circumstances.

The Service Assessment can be read HERE.

The Niles Historical Society, Mike Sisic, and NWS/NOAA contributed some of the photos used in this report.