These Mean Sea Levels.
The first time I heard it was about 10 years back when the local train was crossing the smelly bridge between Mahim and Bandra on a rainy day. The water under the bridge was flowing up-river and the guy hanging from the door was stunned by what he saw. He shouted out to his friend a few inches away from him.
"Something is wrong, the water in the river is flowing in the wrong direction!"
The friends had a discussion until an older man standing next to them explained that it was because of a phenomenon called Tide. "Didn't you boys learn about it school?" He asked the boys who looked like they were in their first jobs after finishing college. Mumbai boys, who have lived all their boys on an Island.
Since them, I have seen dozens of people wondering or talking about the sea level. Most believe that the sea level is related to the rain. The most common one I have heard is during low tide and people saying that the water level rises during the monsoon.
It also explains why a lot of lovers are caught in the act on those rocks at bandstand.
I assume that the tide level warnings in the newspapers have the same meaning as the stock price listings are to me.
Vashi Bridge/Creek during low tide and premonsoon clouds