AIR MAIL
Where today’s air came from
The air arriving over Willow Lake about 5,000 feet above the ground was over the northern Rockies three days ago, and over the southern Plains a day ago, about 1,420 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 14,700 feet up, warming and drying as it sank. Near the ground the air came from the Ohio Valley; at 10,000 feet, from the northern Rockies. Traced back 72 hours through NOAA’s hourly RAP analyses, nine paths at each of three heights.