AIR MAIL
Where today’s air came from
The air arriving over Florence about 5,000 feet above the ground was over the western Atlantic three days ago, and over New England a day ago, about 1,770 miles back along its path. Most of the nine paths traced from around the city agree. Near the ground the air came from the North Atlantic; at 10,000 feet, from the Atlantic off the Carolinas. Traced back 72 hours through NOAA’s hourly RAP analyses and the GFS beyond them, nine paths at each of three heights.