AIR MAIL
Where today’s air came from
The air arriving over The Forks about 5,000 feet above the ground was over the Mid-Atlantic three days ago, and over the western Atlantic a day ago, about 1,560 miles back along its path. Most of the nine paths traced from around the city agree. It came down from about 11,400 feet up, warming and drying as it sank. Near the ground the air came from Canada; at 10,000 feet, from the Mid-Atlantic. Traced back 72 hours through NOAA’s hourly RAP analyses and the GFS beyond them, nine paths at each of three heights.