Why the Global Downward trend of Tropical Activity?

[hurricaneCW]

What's going on? It seems that for the past couple of years at least, the global tropical activity has been strongly reduced. The Western Pacific which normally produces dozens of powerful storms barely produced anything this season. The east pacific may have had Celia, but July has had nothing. Now the Atlantic has been really quiet against what should have been a very favorable pattern for numerous storms. Is it global warming. Has the shear increased globally? Has dry air become more dominant? What's causing all of this?

[KWT]

I'll take a punt and say its not a surprise the deep ole solar min came along at exactly the same time as the downswing, as did the -PDO phase kick in stronger (I believe the 1998-2000 signal was a false dawn, this is the true starting point of the -PDO cycle) and those two factors play a part.

Of course if we take the 1998 analog, its still VERY early days.

Actually the global picture is nearly identical with 1998 right now, 2010 arguably a touch more busy at this stage.

1998 didn't get its first long lived system in the WPAC till the 22nd of August, Bonnie didn't get going till about the same time, so we are ahead of the curve thus far compared to that year.

[abajan]

I don't know why folk are getting the impression that the Atlantic has been quiet this year. Even when we consider the forecast for numerous cyclones this year, this simply has not been the case. Comparison with past seasons will clearly show 2010 thus far to be above the normal in activity.

[KWT]

Indeed Abajan, of course we aren't at the levels of some of the hyperactive seasons that have been banded about but we are still above average providing Colin does form from 91L soon.

[Cookie]

What's going on? It seems that for the past couple of years at least, the global tropical activity has been strongly reduced. The Western Pacific which normally produces dozens of powerful storms barely produced anything this season. The east pacific may have had Celia, but July has had nothing. Now the Atlantic has been really quiet against what should have been a very favorable pattern for numerous storms. Is it global warming. Has the shear increased globally? Has dry air become more dominant? What's causing all of this?

just cause the last few years haven't been 2005 esk, doesn't mean where on quieter trend for hurricanes.

[Macrocane]

If you look at the name of the thread it says GLOBAL trend and the Global trend is downwards since 2005, you can see that at Ryan Maue's site, so hurricaneCW is right:

http://www.coaps.fsu.edu/~maue/tropical/