AIR MAIL
Where today’s air came from
The air arriving over Allagash about 5,000 feet above the ground was over the western Atlantic three days ago, about 1,030 miles back along its path. The nine paths traced from around the city fan out, so treat that as a best guess. It rose from near the ground on the way. Near the ground the air came from Canada; at 10,000 feet, from the Atlantic off Florida. Traced back 72 hours through NOAA’s hourly RAP analyses and the GFS beyond them, nine paths at each of three heights.