Dry air continues to own the Central Atlantic, thanks in large part to plumes of dust being kicked up and shot west over the Atlantic Ocean from the Sahara. This dry plume of air was a large factor in the demise of our most recent tropical entity, Erin, and has been an effective defense against any storms developing in the eastern Atlantic so far this year.
Granted, we're not even at the halfway mark of 2013's tropical season...and in some years, we've recovered from slow starts to mow down a large number of named storms before the season is out (such as 2010, which had 19 storms before the year was out). However, we are behind the pace of the last two years by a fair amount (2011 and 2012 were both on their season's respective "I" storm at this point in the season).
Compared to the past seven years, 2013 is ahead of 2010, 2009, and 2006 and at the same pace of 2007. It's running in the middle of the pack, so to speak. 2006 and 2009 were El Nino seasons, 2007 and 2010 were Nina years...2007 & 2010 both ended up on the more active side but both were a bit slower in getting fired up.
Granted, climatology suggests that, eventually, there will be additional tropical cyclone development. We're three weeks out from the season's peak...things WILL pick up at some point. If you look at the satellite shot up at the top, you can see that there are two stronger tropical waves over Africa that will emerge over the coming days. The key issue for them, just like with Erin, is the dry air over the Central Atlantic and the Saharan Air that's stabilizing the atmosphere and preventing any tropical development from taking place. The stable atmosphere, if these MJO propagation modeling forecasts are right, have another week to ten days in place in the Central Atlantic. It might be enough to keep these next two waves weak...perhaps zap them completely...and it wouldn't shock me if we end August in a pretty similar spot for named storms compared to where we are now. However, the quiet tropical season won't last forever.