Watts Up With That?
Oct 8, 2010
Dr. Ryan N. Maue’s 2010 Global Tropical Cyclone Activity Update
With the 2010 North Atlantic hurricane season winding down without a United States hurricane landfall, Drudge posted a headline suggesting that the seasonal hurricane forecasters blew it. Indeed, he has written this headline for 4-years in a row now by linking to my Florida State University website. While the number of storms has been accurately predicted by the soothsayers (including Rush Limbaugh), the lack of impact upon the US mainland has left many wondering: is this it?
While the North Atlantic sees ~10 storms per year, the annual global total is 80 to 90! So, how is the rest of the globe doing in terms of tropical cyclone (TC) activity? Absolutely cratering — and in in the Western North Pacific typhoon basin, at historical lows. Indeed, with the Earth undergoing Global Climate Disruption, natural climate variability has played the ultimate trump card and left global TC activity at 33-year lows!
From my FSU website:
Current Year-to-Date analysis of Northern Hemisphere and Global Tropical Cyclone Accumulated Cyclone Energy (ACE) AND Power Dissipation Index (PDI) has fallen even further than during the previous 3-years. The global activity is at 33-year lows and at a historical record low where Typhoons form in the Western Pacific.
While the North Atlantic has seen 15 tropical storms / hurricanes of various intensity and duration, the Pacific basin as a whole is at historical lows! In the Western North Pacific stretching from Guam to Japan and the Philippines and China, the current ACE value of 48 is the lowest seen since reliable records became available (1945) and is 78% below normal*. The next lowest was an ACE of 78 in 1998. The Northern Hemisphere overall (including the North Atlantic) has the lowest ACE since 1977, the year of the Great Climate Shift and flip in the phase of the Pacific Decadal Oscillation.
See figure below for visual evidence of the past 40-years of tropical cyclone activity.
Figure: Year-to-Date (October 7) Accumulated Cyclone Energy (ACE; units: 10^4 knots^2) for the Northern Hemisphere as a whole (top blue time series) and for the combination of the Western North Pacific (WPAC), Eastern Northe Pacific (EPAC), and Northern Indian (NIO) basins (bottom gray time series). The difference between the two lines is therefore the contribution of the North Atlantic hurricane basin. Similar figure for Power Dissipation Index (units: 10^6 knots^3)
…And global tropical cyclone during the past 33-years (Southern Hemisphere cyclone data gets progressively spotty prior to the routine monitoring of the global oceans by geostationary satellites):
Figure: Global and Northern Hemisphere Accumulated Cyclone Energy: 24 month running sum through September 30, 2010. 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/light blue boxes). The area in between represents the Southern Hemisphere total ACE.
Global TC Activity remains at 33-year lows. — The last 24-months of ACE at 1090 represents a decrease from the previous months and a return to the levels of September 2009…Since Hurricane Katrina (August 2005) and the publication of high-profile papers in Nature and Science, global tropical cyclone ACE has collapsed in half. This continues the now 4-consecutive years global crash in tropical cyclone activity. While the Atlantic on average makes up about 10% of the global, yearly hurricane activity, the other 90% deserves attention and has been significantly depressed since 2007.
Otto will soon be undergoing extratropical transition and succumb to the vertical shear which becomes progressively more hostile to hurricane activity in the Atlantic as the season wanes. The number of storms ranks fairly highly in terms of the historical record — even with the paltry contributions by Bonnie, Gaston, and Nicole. The ACE to date (October 8 00:00) is 137, which ranks 2010 as the 16th highest since 1950 just behind 2008. Sorted List
Here is the yearly ACE total figure for the past 61-seasons (note: no trend)
While there are some qualms about the wind speeds prior to the satellite era, it’s clear that some sort of multi-decadal signal is present (i.e. AMO). If some weak, short-lived storms were missed, then so what, their ACE contribution is inconsequential. How does this ACE compare to the seasonal forecasts of NOAA, Gray and Klotzbach, and the UK MetOffice? Not quite there yet.
How skillful or useful are these ACE forecasts? Well, just based upon the knowledge of a La Nina summer/fall, one would calculate an average ACE of 116 compared to an El Nino average ACE of 68 by simply looking at the Multivariate ENSO Index and the hurricane records from 1950-2009. Add in knowledge of the so-called North Atlantic active period beginning ~1995 and one could come up with this number rather painlessly.
The North Atlantic was not the only ocean seeing quiet tropical cyclone activity. When using the ACE cyclone energy scale, the Northern Hemisphere as a whole is historically inactive. How inactive? One has to go back to 1977 to find lower levels. Even more astounding, 2007 will be the 4th slowest year in the past half-century (since 1958).
The 2007 Atlantic Hurricane season did not meet the hyperactive expectations of the storm pontificators. This is good news, just like it was last year. With the breathless media coverage prior to the 2006 and 2007 seasons predicting catastrophic swarms of hurricanes potentially enhanced by global warming a la Katrina, there is currently plenty of twisting in the wind to explain away the hyperbolic projections. The predominant refrain mentions something about being lucky and having escaped the storms, and just wait for next year.
And suggested we “Bring out the Broom on the 2007 Season“:
With October nearly done circling the drain, I figure it is about time to bring out the broom: Northern Hemisphere tropical cyclone activity is at historically low levels .
In fact, September 2007 suffered the lowest ACE since 1977 ! Even scarier, so far 2006 and 2007 have the lowest October ACE since 1976 and 1977. And, unnaturally, Sept-Oct 2007 is the lowest since 1977.
Yet, the tropical cyclone season was not shaping up to be such a ghastly bust. For about a week in June, NH ACE was exceeding climatology but then bit the proverbial dust until mid-August when a noticeable comeback ensued. It has been downhill since.
Here’s the Drudge Report screen cap as a refresher of the other news going on (with Hillary Clinton picture goodness): Forecasters Blow It, Again: ’07 Hurricane Season may rank as most ‘inactive’ in 30 years
And, just for fun, additional screen caps from 2008 and 2009. Indeed, Matt Drudge mixes up the overall global inactivity with the North Atlantic basin alone. Regardless, the story is now the same for 4-years in a row: North Atlantic hurricane forecasts hopelessly overblown against a backdrop of plummeting global tropical cyclone activity overall.
So, I guess it is appropriate to begin the 2011 Atlantic season predictions. I leave it to Rush Limbaugh, who on Thursday’s program uncorked his highly accurate scheme with help from Roy Spencer: between 0 and 40 storms.
RUSH ARCHIVE: I’ll make a prediction. There will be between zero and 40 storms this year, there will be between zero and 40 to become hurricanes, between zero and 40 that become major hurricanes, and between zero and 40 that impact the United States Gulf or East Coasts, and between zero and 40 who wipe out a city. There you have it. My prediction is going to be more accurate than anybody else’s. You wait and see.
RUSH: That’s my prediction for the 2011 hurricane season. The first out, by the way, with my prediction, and probably a prediction made with more confidence than anybody else’s prediction, which won’t come until next spring. Again, another shining example of being on the cutting edge. You learn about everything here first.
This article was posted: Friday, October 8, 2010 at 4:02 am