Oh, What a Difference a Year Makes

At this time last year, the Atlantic Ocean, Caribbean Sea and Gulf of Mexico had already seen five named tropical systems including three hurricanes. The Gulf Coast saw all five make landfall on her shores - three in the US (two of those hurricanes) and two in Mexico.

This year has seen a dramatic reversal of last year with only one named storm thus far, Tropical Storm Alberto, that hit Florida in June. Forecasters at the National Hurricane Center are predicting at least another five days with no tropical storm formation of any kind. It is conceivable that, by the time we get even another depression, it will be the end of July. By comparison, there were eight named storms by August 2 in 2005.

So, why so quiet? Well, as Dr. Jeff Masters at Weather Underground points out in his latest blog, wind shear rules, and that's just not a clever way of saying we like it either.

Wind shear in thunderstorms can produce hail, tornadoes and severe turbulance for airplanes. But that isn't the kind of shear that is causing a quiet season thus far in the tropics. Atlantic wind shear refers to wind currents in our atmosphere. This season, shear levels across the Caribbean and Gulf of Mexico have been high preventing the formation of tropical storms that require calm upper-level winds to survive.

There have been other minor factors including slightly cooler sea temperatures than 2005 and dust blowing off the African coast into the air above the Atlantic, but shear has been the dominating force as Dr. Masters points out.

The busiest part of the hurricane season is yet to come, however - between mid-August and the end of September. But, it is nice to know that our quiet early hurricane season and our blue skies will continue a little longer.

Photo courtesy of Flickr user paper by design.