Gustav’s Upwelling

Upwelling is a phenomena that occurs when a hurricane (or tropical storm, for that matter) churns the ocean water. The pounding waves, some very high, causes some cooler water to rise to the surface and lowers the SST (Sea surface temperature) Of course, a slow moving hurricane, especially one moving along at about 5 to 8 mph, has longer time to anger the waters.

The perfect hurricane for considerable upwelling is a large, slow moving one. Gustav became a large and major hurricane over the Gulf.

Hurricanes love water temperatures in the mid-80s or higher. SSTs 85-89 are a big feast for them. If a second hurricane or tropical storm follows too closely, the cooler SST can cause it to weaken a bit. But a lot of other factors can cause one to weaken also such as wind sheer aloft and drier air getting sucked in (not unusual at all in the Gulf of Mexico.

Here is a selection of SSTs from observations around 8 o’clock this morning:

….80 just off Grand Isle, Louisiana (that community was overrun by big storm surge)
….81 Pensacola Bay
….83 buoy 64 nautical miles south of Dauphin Island
….79 buoy 22 miles SE of Biloxi
….82 buoy 115 miles SE of Pensacola
….85 Mid Gulf buoy
….86 Buoy 42056, NW Caribbean
….85 Buoy 42057 West Caribbean
….85 Buoy 40258 Central Caribbean
….85 Buoy 42059 East Caribbean East Caribbean

So you can see there was some upwelling and cooling along Gustav’s path as he moved NW across the Gulf. Not sure how long it will take for recovery. Probably a bit slower now since we are heading toward autumn.

I don’t know a single weather human that does not realize that hurricanes have a mind of their own and often, especially near landfall, there can be hour-by-hour surprises.

And I know I am being semi-silly (SOP for me it seems) but I sure would like to have had a remote video camera around the neck of the largest shark in the path of Gustav and watch his actions. Probably a nervous breakdown!

Again, a big cheer for the National Hurricane Center for their excellent record with Gustav.

LATE NOTE ON HANNA
She has been demoted to a Tropical Storm but probably not for long.

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