AIR MAIL
Where today’s air came from
The air arriving over Lowell about 5,000 feet above the ground was over the northern Rockies three days ago, and over the central Plains a day ago, about 1,510 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 Ozarks; at 10,000 feet, from Texas. Traced back 72 hours through NOAA’s hourly RAP analyses, nine paths at each of three heights.