Ryan N. Maue's Seasonal Tropical Cyclone Activity Update

Florida State University ^ | October 30, 2009 | Ryan N. Maue

[devere]

North Atlantic Hurricane Season slowest since 1997. Global and Northern Hemisphere Tropical Cyclone Activity remains near 30-year historical lows -- three years in a row now of considerably below-average activity globally. Consequence of the transition from La Nina to El Nino during the past year. Oct 29: The North Atlantic hurricane season has not produced a storm in over 3-weeks and, if no more develop, the season overall would rank as the slowest since the El Nino year of 1997. Hurricanes Bill and Fred accounted for over 82% of the Accumulated Cyclone Energy [ACE**] -- a metric that combines intensity, duration, and frequency of hurricanes and tropical storms during a year. The remaining storms were weak, rather short-lived and unremarkable. Indeed, the Accumulated Cyclone Energy [ACE] of 44 ranks among the slowest during the past half-century. Elsewhere, the Northern Hemisphere and Global ACE when calculated either with 12- or 24-month running sums, remains just above historical 30-year lows. Indeed, the global ACE sunk to record low levels during the early summer prior to the typhoon activity in the Western Pacific and the hurricane activity in the Eastern Pacific. While it may seem like the world has experienced considerable tropical cyclone activity lately, 2009 as a whole is still well behind normal or climatology. The previous Southern Hemisphere cyclone season including the Southern Indian and Pacific Oceans along with the Australian region produced historically low levels of ACE (from Oct 2008 - Apr 2009). So a global sum during the past 12 or 24 months will simply show the depressed tropical cyclone activity experienced.

This is a natural consequence of the rather unusual flip from strong La Nina to El Nino conditions during the past calendar year, which did not happen at all during the period of 1976-2006 as indicated by

[devere]

My theory is that carbon dioxide emissions stop hurricanes. No I don't have any solid evidence, but who needs real evidence any more?

[Bigg Red]

Nature is doing what nature does. And, in terms of climate, there is not much effect that human activity can have on such systems.

[Mind-numbed Robot]

Global Warming causes lots of hurricanes. What you are seeing now is Climate Change.