AIR MAIL
Where today’s air came from
The air arriving over Oak Bluffs about 5,000 feet above the ground was over New England three days ago, and over the western Atlantic a day ago, about 1,560 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 Canada; at 10,000 feet, from the western Atlantic. Traced back 72 hours through NOAA’s hourly RAP analyses and the GFS beyond them, nine paths at each of three heights.