AIR MAIL
Where today’s air came from
The air arriving over Steenerson about 5,000 feet above the ground was over southern California three days ago, and over the northern Plains a day ago, about 1,660 miles back along its path. Most of the nine paths traced from around the city agree. It came down from about 10,500 feet up, warming and drying as it sank. Near the ground the air came from Texas; at 10,000 feet, from southern California. Traced back 72 hours through NOAA’s hourly RAP analyses, nine paths at each of three heights.