AIR MAIL
Where today’s air came from
The air arriving over Milford about 5,000 feet above the ground was over the Maritimes three days ago, and over New England a day ago, about 990 miles back along its path. The nine paths traced from around the city fan out, so treat that as a best guess. It came down from about 9,200 feet up, warming and drying as it sank. Near the ground the air came from the North Atlantic; 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.