AIR MAIL
Where today’s air came from
The air arriving over New Diggings about 5,000 feet above the ground was over a point about 180 miles to the south three days ago, and over the Mississippi Valley a day ago, about 490 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 Great Lakes; at 10,000 feet, from the central Plains. It has stayed over land, which is why it feels dry. Traced back 72 hours through NOAA’s hourly RAP analyses, nine paths at each of three heights.