Ice Flowing Upriver: Surprising Sight at Pittsburgh Point

[flatmaster]

Here is the point at Pittsburgh. The Allegheny is bringing in ice from the top of your picture. the Mon is flowing in from the right. Both rivers empty into the Ohio off to the left. Somehow, Ice flowed up the Mon. THe current is low today with a slight wind blowing left to right on your picture. However, I'm supprised this amount of Ice came up river. My guess is at least 300 ft. Perhaps the Al is flowing slightly faster, creating an eddy on the mon side of the point?

 

[LURCH]

Are you sure ice isn't flowing downstream and piling up in the upstream direction ("backing up" the river)?

 

[flatmaster]

It's farily clear down the ohio. I don't think it's backup.

 

[flatmaster]

There has been no ice coming down the Mon at all. This all must have come from the Allegheny.

 

[flatmaster]

I suppose it's possible the ice froze in this position. However, it wasn't there this morning after the cold night.

 

[Xnn]

It looks like the ice is towards the right (south) side of the Allegheny.
There is probably a strong north wind blowing it that way.

If so, then maybe it's the wind that is blowing it into the Monongahela
and its flow is not all the strong so there is a calm eddy section
without much surface flow.

 

[matthyaouw]

My guess is eddies & various chaotic flow patterns. When I was studying water quality monitoring we were told never ever bother trying to measure anything near a river confluence. If the water in each tributary is a different temperature or salinity, they will not mix readily and can flow some distance keeping quite separate from each other. Nowhere near as simple as you would imagine.

 

[flatmaster]

Furthermore, you can see the zone where the waters don't mix. The "Muddy mon" is a bit browner. Also, you can see ice floating at the interface of the two bodies of water. However, closer to the actual point, the ice doesn't follow this line.