Sunday, May 29, 2011

Belmont Harbor Water Surge or Seiche

Today was another interesting weather day at Belmont Harbor.  We came down early afternoon during a downpour to find the south parking lot deeply flooded because a storm drain was badly clogged.

During lunch the view at the Chicago Yacht Club's Belmont station turned gray.  The fog returned after the storm passed.  In the period of about 10 minutes visibility dropped to a few hundred yards.  The fuel dock (perhaps 200 yards away) was completely obscured!

Low water after the May 29 storm.  High water was over the  bottom
of the lowest wall board, just 15 minutes before this was taken .
Most interesting was the change in water level.  I noticed a pretty hard rocking of several boats as if from a large boat wake, odd because no boats were moving and the wind was calm.  I also noticed the water was over the bottom of the lowest wall board near the cranes, unusually high.  Normal water level is somewhere closer to the white fender.  Using the ladder as reference, this was close to a 2 foot drop within about 15 minutes.

I don't know if this was technically a seiche or just a change in water level due to pressure change, but it was neat to watch.  I also noticed current around some of the boats.  Its not uncommon to see a swirling current at the harbor entrance.  I imagine it was pretty strong today.

I found two interesting articles explaining seiches.  The first, Seiches:  Sudden, Large Waves a Lake Michigan Danger is from Illinois State Geological Survey.  The second is Sloshing the Lakes:  The Seiche

Finally, the low clouds had an interesting texture and the wind shift to southerly winds brought noticeably warmer air.

Looking south after Sunday's storms.  Fractocumulus clouds?

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