Lee waves downwind of the Baraboo Bluffs

October 10th, 2007 |

GOES-12 visible images (Animated GIF)

“Lee waves” are sometimes seen just downwind of significant topography (such as high mountain ranges) when strong winds are perpendicular to the ridge lines — but even relatively subtle terrain features can produce lee wave clouds that are evident on satellite imagery (one such example of lee wave clouds in a region of subtle terrain was seen over the Bay of Fundy in Canada in August 2007). Brisk northwesterly winds were prevalent across much of southern Wisconsin during the day on 10 October 2007, and an animation of GOES-12 visible channel imagery (above) revealed a packet of quasi-stationary lee waves immediately downwind of the Baraboo Bluffs.

An AWIPS high resolution topography image (below) shows that the narrow Baraboo Bluffs terrain feature (located just to the south-southeast of Baraboo/Wisconsin Dells airport, station identifier KDLL) only has a maximum altitude of about 1503 feet above sea level (brown enhancement), but that was high enough to act as a barrier to the boundary layer winds and induce the lower tropospheric wave cloud features. Aircraft flying in the vicinity of such lee waves can encounter turbulence at times — however, in this case there was only one isolated pilot report of turbulence at 3500 feet above ground level over far southwestern Wisconsin (well to the west of the lee wave cloud features).

AWIPS topography image

Leave a Reply