More About the Big Waves on Lake Superior

UPDATE: Blog reader Donnett identifies the bridge as the Aerial Lift Bridge, on Lake Superior shore in Duluth, but Chris Burt [JessePedia], Author of "Extreme Weather" questions whether the photo was even taken during this storm, saying that heavy snow should have been occurring at the time. Duluth received 9 inches of snow during the storm, most of it at the time of highest waves, which Chris says were 12 to 18 feet according to NOAA.

ORIGINAL REPORT:

You may have noticed in the ABC News Video of the storm wrap-up on Friday, that there was some incredible overnight video of large waves sweeping past a bridge on Lake Superior [Google Map]. I couldn't find out any information on where the video was taken (if you know, email community @ accuweather.com), but I also found daytime video. Both are shown below. The daytime video is courtesy KAAL, who says that wave heights reached 8 feet on the lake.

NOTE: VIDEO MAY HAVE ADS; VIDEOS NOT AVAILABLE ON WIRELESS DEVICES

Some blog readers have asked: What caused these waves? Large waves on the Great Lakes are unusual, but this isn't rocket science. With sufficient fetch (wind blowing over water), waves are created. In this case, winds rotating counter-clockwise around the large low pressure system in the Midwest (pressure map below) were quite strong (longer arrows on the map below) over Lake Superior.

This situation was a more tame version of what caused huge chunks of ice to fly through the windows of lakefront homes on Lake Erie in January. In this case, winds were not as strong or as constant in direction, so no significant storm surge was observed* (Duluth was up and down 10 inches (graph from NOAA Lakes Online) and winds topped out around 62 mph at the Duluth station (graph from NOAA CO-OPS). The RTMA current conditions analysis on AccuWeather.com Pro also indicated similar winds, 55-60 knots, over the middle of the lake (map), although I'm not sure where that data came from since all the buoys (which could have showed us wave heights) are still out-of-service due to winter ice.* Coastal stations at either end of Isle Royale (the big island in the northwest part of the lake) PILM4 and ROAM4 also showed winds in the 40-50 knot range (graph and graph from the National Data Buoy Center). The RTMA map also shows the streamlines (direction of flow of imaginary points added into the "flowing stream" of the winds) converging over the lake; that added to the fact that a long frictionless fetch was available, may have been what caused the winds to be so strong.

*According to this map, the ice is gone, so let's get those NOAA buoys back out there, NOAA boys!