WRAL WeatherCenter Blog

A hurricane season in 4 minutes!

Posted June 7, 2010 6:51 a.m. EDT

The 2009 hurricane season was a relatively quiet one with nine named storms and three hurricanes, but nonetheless makes a fascinating animation in a time-compressed infrared satellite animation recently posted by NASA and NOAA. The movie shows a satellite's-eye view of the tropical Atlantic, with a smooth fast-forward time lapse that starts on August 1st and ends around November 14, capturing the life span of all the tropical depressions, storms and hurricanes of the season, which are labeled as they progress along their tracks.

As you watch the dynamics and thermodynamics of the atmosphere unfold, one thing that really jumps out partway through is a reminder of how much the season was influenced by El Nino, which typically limits tropical cyclone formation or intensification, in large part by enhancing vertical wind shear across the storms, which reduces their ability to develop or maintain the organization they require to operate efficiently. With the sped-up nature of the movie, this shear-based disruption is especially visible in the cases of Erika, Fred and TD 8.

Of course, it is quite possible we'll see a much more active season ahead. While there can never be absolute guarantees on such forecasts, the consensus of outlooks from NOAA, Colorado State University and NC State University indicate well-above-normal activity, based in part on record-warm sea surface temperatures in the so-called "main development region" in the southern North Atlantic where most of the more powerful hurricanes tend to form, and on an expected transition from El Nino to either neutral or La Nina (even more favorable for Atlantic storms) conditions. This transition is looking more and more likely, as El Nino essentially collapsed in May, and deep cooling in the central and eastern equatorial Pacific appears supportive of La Nina development by mid to late summer, just in time for the peak of hurricane season.