AIR MAIL
Where today’s air came from
The air arriving over Champion about 5,000 feet above the ground was over a point about 420 miles to the southwest three days ago, and over the Great Lakes a day ago, about 1,200 miles back along its path. The nine paths traced from around the city fan out, so treat that as a best guess. Near the ground the air came from a point about 460 miles to the southwest; at 10,000 feet, from the California coast. Traced back 72 hours through NOAA’s hourly RAP analyses, nine paths at each of three heights.