April 15, 2009. We see two very different Smokies today and the highest peaks in the southern Appalachians provide an atmospheric boundary.
On the west side of the mountains we see low dense stratus clouds, but on the east side we have clear skies. As the atmosphere is uplifted over the the highest ridge of mountains there’s cooling and abundant cloud formation. That’s half the story.
The winds are form the northwest and the Smokies (along the Tennessee/North Carolina stateline) provide the highest barrier the winds must cross over. On the leeward side, as the winds cross over the mountains, they descend, warm, and prevent cloud formation especially just east of the summits.
Link to more: http://pixel.outragegis.com/v/weather_maps/090415_TwoSmokies/
These images and animation show a textbook situation of topographic control of weather, but over a very large area.