AIR MAIL
Where today’s air came from
The air arriving over Fountain Prairie about 5,000 feet above the ground was over the southern Plains three days ago, and over Texas a day ago, about 1,200 miles back along its path. The nine paths traced from around the city fan out, so treat that as a best guess. Near the ground the air came from the Mississippi Valley; at 10,000 feet, from the southern Rockies. Traced back 72 hours through NOAA’s hourly RAP analyses, nine paths at each of three heights.