"Ophelie, our leech, is since time immemorial a meteorological indicator.
If atmospheric pressure goes down, she does, too.
If she is lying low in the bottom of the jar, bad weather and rain will come soon.
If atmospheric pressure goes up, she will rise up forthwith to the surface of the water, and sunshine and good weather will not be far away."
Here's la charmante Ophelie. Get out your umbrellas?
My sources seem to indicate the opposite.