
© The Weather Channel (screen capture)
Current Satellite Image
(The highest cloud tops, corresponding to the most vigorous convection and heaviest rain, are shown in the dark red and pink colors.)
A Mediterranean Sea low-pressure system may develop into a "medicane", a nickname for systems in this area that gain some characteristics of Atlantic subtropical or even tropical cyclones, and may deliver more flooding rain to already flood-ravaged parts of Greece.
This area of low pressure, named
Numa by the Free University of Berlin, is currently in the Mediterranean Sea southeast of Italy and will track east into Greece this weekend. Moisture from the broader gyre of low pressure associated with this system has already brought heavy rainfall and deadly flooding to portions of Greece.
More rainfall is expected in the region through Saturday, as this area of low pressure is expected to move east toward Greece.
Numa's center is currently located just south of Puglia, Italy. Showers and thunderstorms have become more concentrated near the low-pressure center, wrapping into southeast Italy.
As mentioned earlier, various other clusters of heavy rain had propagated well to the east over Greece, Albania, Macedonia, Kosovo, Serbia, Bulgaria and western Turkey.
As you can see below, current water temperatures there are only around 20 degrees Celsius, below the 26 degrees Celsius (79 degrees Fahrenheit) normally needed to sustain a tropical cyclone in, say, the Atlantic or eastern Pacific basins.
Comment: It's possible that this is man-made pollution, but having rivers and lakes turn red is not a localized phenomena and can't always be explained away as the result of pollution: