Thursday, October 23, 2014
Inquirer Daily News

Bolaris: Surprisingly 'dirty' reason there are so few hurricanes

Hurricane Arthur (Photo by NOAA via Getty Images)
Hurricane Arthur (Photo by NOAA via Getty Images)

Arthur and Bertha were the only two Hurricanes to form so far this season, but the time frame for maximum storm development is now. 

If you remember, Arthur scooted well off the New Jersey coast during the 4th of July holiday, making for some interesting weather chatter and some rough surf. It did make a land strike along the Carolinas -- and Canada, of all places. Arthur was the strongest as a category 2 with 100 m.p.h. wind at its peak. Bertha never even made a U.S strike. 

As I said, we’re approaching what’s usually the most troublesome time for Hurricane formation. I've been watching tropical wave after wave forming near the Cape Verde islands off the African coastline. This is the region where the most intense hurricanes form because they have thousands of miles of ocean to gain strength. 

But recently these waves have been obliterated by dust - better known as Saharan dust storms. These dust storms form over Northern Africa and travel thousands of miles westward across the Atlantic. 

The main issues from the Sahara dust were at first limited to air pollution alerts across the Caribbean and impacting coral development. New studies suggest the dust that is getting blown across the tropical Atlantic and smothering tropical storm development. 

How?

1. A surge in the mid-level African Easterly Jet increases wind shear. (A wind shear stifles tropical development by disrupting the outflow of a hurricane/storm, suppressing its intensification.)

2. The developing storm now draws dry air into the circulation. Tropical systems feed off warm moist air and latent heat from the ocean. 

3. An inversion takes place, meaning temperatures increase with height due to the warm layer from 5,000 to 15,000 feet from the layer of Sahara dust. This stabilizes the atmosphere. Storms feed on an unstable atmosphere, cooling with height. 

4. Finally, the massive amounts of dust limits sunshine, energy from the sun helps to percolate these storms.

El-Nino is playing a role as well, but future studies might suggest that it is the Sahara Dust becoming the new star that helps to smother the Hurricane season.

As the band Kansas sang ...'Dust in the wind

All we are is dust in the wind

Oh, ho, ho. same old song

just a drop of water in the endless sea...

John Bolaris Philly.com
Also on Philly.com
Stay Connected