Ryan N. Maue's 2010 Global Tropical Cyclone Activity Update
August 31 : With the month of August ended, it is time to update the ACE graphics and decide whether the recent increase in global activity, 3 storms in the Western Pacific and 3
storms in
the Atlantic is evidence of a return to normalcy. With Danielle and Earl being Cape Verde-type storms which recurve into the middle-latitudes, they last a long time and generate
considerable ACE. However, it is just barely enough to keep up with climatology.
August ACE for the Northern Hemisphere was 63 which is much less than the climatological average of 115. The Western Pacific again was much below average. It was indeed the Atlantic that
produced two long-lived storms, Danielle and Earl that picked up some of the slack. The global and NH ACE remains at/near 30-year lows.
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Perspective (Aug 18): With the anticipated development of a powerful Cape Verde hurricane (Danielle?) during the next week, considerable ACE will accumulate. For the Northern Hemisphere, the normal ACE per day is 5 units. This corresponds to the daily input of a 110 knot hurricane/typhoon or a major status (near Category 4) on the Saffir-Simpson scale. This is required just to keep up with climatology. It is when multiple hemispheric cyclones are concurrently spinning at high intensities does the ACE really add up. There is not much sign in the Pacific of any activity, thus the Atlantic will really need to pick up the slack.
Global TC Activity remains at 30-year lows at least -- 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. See Figure below.
Northern Hemisphere year-to-date ACE is now over 50% below normal. The Western North Pacific is at 16% of normal (or the past 30-year average). The Eastern Atlantic has the potential to produce a tropical storm during the next week which would be named Danielle -- which the ill-fated, but heavy rain producer - TD5 failed to become.
August 17: Current 7-10 day forecast models see potential development in the Eastern North Atlantic off the coast of Africa as the Cape Verde Season ramps up.
Colin and Bonnie both go into the books as a couple of the weakest tropical cyclones on record. TD5 failed to develop into a storm. No storms were recorded in the Eastern Pacific during July!
August and September will have to be record activity for the hurricane forecasts to pan out in the North Atlantic. See discussion at Watts Up With That?
July 31: Current ACE for July in the Northern Hemisphere is 14.2 and consists of Alex, Chanson, Bonnie, and Chanthu. No ACE was recorded in the Eastern Pacific.
Figure: Global and Northern Hemisphere Accumulated Cyclone Energy: 24 month running sum through August 31, 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/lime green boxes). The area in between represents the Southern Hemisphere total ACE.
Note: Southern Hemisphere tropical cyclone data is spotty prior to the introduction of reliable satellite monitoring, thus the ACE represented at the beginning of the 1980s is likely underestimated due to missing data. Thus, it is possible that the current global collapse in TC ACE is comparable to lows experienced prior to 30-years ago...
Figure: Northern Hemisphere cumulative ACE per day of year from July - December. See legend for appropriate axis of each basin or NH total.
Climatological yearly ACE and HDAYS are based upon 1980-2009 values (last 30 years)
Daily Cumulative ACE file
[Month, Day, IO, EPAC, NATL, WPAC, NH]
2010 Northern Hemisphere Tropical Cyclones
Maximum Wind Speed & ACE per storm (ATCF operational intensity estimates)
** 2007-2009 Historical TC Activity -- Page Link