Monday, April 02, 2012

Could Tropical Season Be A Statistical "Dud"?

Since 1995, the average season has had about 15 named storms in the Atlantic. This could be one of the rare seasons where activity is down a bit from our more active trend...and a season like 2006 or 2009 may be on tap.

If you can't remember either of those seasons -- nobody will blame you.  2006 had 10 named storms, most notably Ernesto along the East Coast, with 2009 bringing Ida (and the coastal storm off of the East Coast in November)...but only nine total storms for the season.

Why, you may ask?  The reason is the increasing potential for El Nino's return.  Ninos were last en vogue and striking poses in the Pacific in the summers of 2006 and 2009, resulting in below average activity for the Atlantic.  El Nino patterns change not only the surface waters off of the Pacific coast of South America but they also alter the upper level patterns in the tropical Pacific and Atlantic as a result...the warming waters of the Pacific allow for more tropical cyclone development, which results in outflow and shear over the Atlantic and a more hostile setup for tropical development.

Most of the computer modeling used to track the long range development of El Nino or La Nina suggests that the Nino pattern will take shape in the early to mid parts of Summer, perhaps peaking this Fall.  Even the least optimistic modeling out there suggests a neutral ENSO pattern, which could result in slackened activity in the Atlantic as the Pacific becomes a bit more favorable on paper.

The precipitation anomaly modeling from the Euro computer model (see above) shows a rather mundane tropical Atlantic AND Pacific as well -- this could be a year where Ninos don't necessarily spawn storms close to the Mexico coast but do spawn some tropical development farther in the Pacific?  The Atlantic shows a relative lack of precipitation across it compared to average, which could suggest a slightly less active season.

It's still pretty early in the game to talk specific numbers on tropical systems but trends do suggest that we may not be in for the level of activity we saw the last couple of years.  We'll have our hurricane season outlook in early May.