New Paper: Maue (2011) Recent historically low global tropical cyclone activity:
During the past 6-years since Hurricane Katrina, global tropical cyclone frequency and energy have decreased dramatically, and are currently at near-historical record lows. According to a new peer-reviewed research paper accepted to be published, only 69 tropical storms were observed globally during 2010, the fewest in almost 40-years of reliable records.
Furthermore, when each storm's intensity and duration were taken into account, the total global tropical cyclone accumulated energy (ACE) was found to have fallen by half to the lowest level since 1977.
In his new paper, "Recent historically low global tropical cyclone activity", Dr. Ryan Maue, a meteorologist from Florida State University, examined the last 40-years of global hurricane records and found strikingly large variability in both tropical cyclone frequency and energy from year-to-year. Since 2007, global tropical cyclone activity has decreased dramatically and has continued at near-historical low levels. Indeed, only 64 tropical cyclones were observed globally in the 12-months from June 2010 - May 2011, nearly 23-storms below average obliterating the previous record low set in 1977.
On average, the North Atlantic including the Gulf of Mexico and Caribbean Sea accounts for about 1/8 of total global tropical cyclone energy and frequency. However in 2010, the Atlantic saw 19 tropical storms, of which 12 became hurricanes as expected (and forecasted) due to the intense La Nina event and continued positive Atlantic Multidecadal Oscillation (AMO). The Atlantic Ocean's accumulated cyclone energy (ACE) corresponded to about 1/3 of the global calendar year output while the Western North Pacific typhoon season experienced a record few number. Seasonal forecasters of Atlantic hurricanes expect a similar but somewhat tempered outcome for the 2011 season, which has yet to get underway.
While the North Atlantic continued a 16-year period of above-normal activity in 2010, the North Pacific including the warm tropical waters from China to Mexico experienced the quietest tropical cyclone season in at least 40-years of historical records. Similarly, the most recent Southern Hemisphere cyclone season, except for the disastrous impacts of Yasi, was also notably below average. All told through June 27, 2011, overall global accumulated cyclone energy and frequency has settled into a period of record inactivity.
June 26, 2011 -- With Meari and Haima weakening and dissipating, the global tropics are very quiet. The ECMWF deterministic runs have a couple potential storms, one in the SW Gulf of Mexico and another along 100W in the Eastern Pacific during the next 10-days. Nothing major is on the horizon for the next 10-days, at least.
June 20, 2011 -- So far this June, the Eastern Pacific has produced Adrian and Beatriz, while the North Indian and Western Pacific saw a total of 3 quite weak tropical storms. The total of 5 global tropical storms brings the 12-month running total to 65 . The average should be around 87.
Globally, tropical cyclone frequency has reached uncharted lows -- only 64 storms were counted from June 2010 to May 2011.
June 10, 2011 As expected, Hurricane Adrian developed in the EPAC, but will not threaten land. As an annular storm, it will persist a bit longer or decay a bit slower than a normal major hurricane over colder SSTs. Tropical Storm Sarika in the WPAC has only reached minimal storm status, 35 kts. Arabian Sea TC 01A has similarly failed to exceed the weakest tropical storm strength (35 knots).
June 7, 2011 Global Tropical Cyclone Frequency has fallen to the lowest levels in recorded history. Only 64-tropical cyclones were recorded during the 12-month period from June 2010-May 2011. And, as most have noticed, it is very quiet -- with only one development likely in the Eastern Pacific (Adrian) during the next 10-days.
Figure 1: (Updated: June 1) Last 4-decades of Global and Northern Hemisphere Accumulated Cyclone Energy: 24 month running sums through June 1, 2011. Note that the year indicated represents the value of ACE through the previous 24-months for the Northern Hemisphere (bottom line/gray boxes) and the entire global (top line/blue boxes). The area in between represents the Southern Hemisphere total ACE
Figure 2: (Updated: June 1) Last 4-decades of Global Tropical Storm and Hurricane frequency — 12-month running sums. The top time series is the number of TCs that reach at least tropical storm strength (maximum lifetime wind speed exceeds 34-knots). The bottom time series is the number of hurricane strength (64-knots+) TCs. The added red lines are linear trends, which serve the useful purpose of delineating the respective time-series mean, since they are flat and parallel. Updated through June 1, 2011. http://www.coaps.fsu.edu/~maue/tropical/