Complex sentence: The 149 tornadoes occurred in 32 hours of continuous activity, which would not break the record held by the 1974 Super Outbreak, which saw 148 tornadoes in 16 hours.
Split into simpler sentences: The 149 tornadoes occurred in 32 hours of continuous activity, which would not break the record held by the Super Outbreak. The Super Outbreak saw 148 tornadoes in 16 hours.