Recent TC Activity (Updated through Oct 10, 2008, 00:00)
| Basin | 2008 ACE | CLIMO ACE | % of NORM | HDAYS | HDAYS Climo | 2007 ACE | 2006 ACE |
| Western Pacific | 152.9 | 212.9 | 72% | 141 | 191 | 209 | 307 |
| Eastern Pacific | 74.2 | 123.7 | 60% | 59 | 114 | 52 | 157 |
| North Atlantic | 123.5 | 87.9 | 140% | 101 | 80 | 68 | 79 |
| North Indian | 14.7 | 7.6 | 193% | 20 | 5 | 44 | 11 |
| Northern Hemisphere | 365.3 | 432.2 | 85% | 321 | 390 | 373 | 554 |
| Southern Hemisphere | 225 | 236 | 95% | Historically poor data | 310 | ||
What should ACE be on October 1 according to climatology (last 30 years)?
Western Pacific -- 196 -- range 80 [1998] - 354 [2004] Actual: 153
Eastern Pacific -- 117 -- range 39 [2003] - 260 [1992] Actual: 56
North Atlantic -- 83 -- range 17 [1983] - 221 [2004] Actual: 122
Northern Hemisphere total -- 403 -- range 273 [**2007**] - 650 [2004] Actual: 345
Figure: Northern Heisphere Monthly ACE values for the past 6 years with yearly values included. 2004 saw over twice the activity as 2007.
How much ACE per day for a given intensity? (knots ACE)
35 0.49 40 0.64 45 0.81 50 1.0 55 1.21 60 1.44 65 1.69 70 1.96 75 2.25 80 2.56 85 2.89 90 3.24 95 3.61 100 4.0
105 4.41 110 4.84 115 5.29 120 5.76 125 6.25 130 6.76 135 7.29 140 7.84 145 8.41 150 9.00 155 9.61 160 10.24
One day at 100 kts = 8 days at 35 kts --- One day at 135 kts = 4.3 days at 65 kts
Review: 2007 Tropical Cyclone Activity
During 2007, the Northern Hemisphere as a whole experienced the lowest ACE hurricane energy & number of hurricane days since 1977. 2007 was the 4th slowest year in the past half-century (since 1958)...Maue, R.N., 2008: Northern Hemisphere Tropical Cyclone Activity (2008, GRL in review, 2008GL035946).
Analysis of integrated global hurricane activity shows that the previous 12-24 months exemplify a continuing decreasing trend since 1997. Since tropical
cyclones occur planetwide throughout the calendar, moving averages of cyclone energy are used to show the global nature of earth's cyclone energy.
Updated: Global and Northern Hemisphere Accumulated Cyclone Energy: 12 month running sum through July 31, 2008
Northern Hemisphere Mean Tropical Cyclone Activity
Using the Accumulated Cyclone Energy metric, the figure below is the average ACE experienced during the past three decades. The mean
calendar year ACE is 557 with the following mile posts: 25% reached on August 4, 50% reached on September 7, 75% reached on October 8. There is
considerable variability year-to-year largely related to the modulation of the Earth's climate system by ENSO.
Table: The variability of Northern Hemisphere ACE is considerable. 1977 and 2007 are examples of well-below average activity while 1992 and 1997 exemplify hyper-active, El Nino enhanced TC activity.
News (09/26) The first category 5 tropical cyclone of the year developed in the Western Pacific named Jangmi
News (09/23) After the spurt of so-called record activity in the North Atlantic, with consecutive alphabetical landfalls, 93L is the only potential entity for future development, and for some reason, is taking its time. Hagiput in the West Pacific is the only active global tropical cyclone.
News (09/13) With the landfall of Ike, North Atlantic ACE has pushed 200% above normal, which is approaching almost double of 2007's total activity. As expected the Eastern Pacific is dead. Typhoon Sinlaku in the WPAC is slowly moving towards Japan.
News (09/08) After Ike, will the North Atlantic go dormant and the rest of the hemisphere pick up in activity?
News (09/03) Except for the North Atlantic, the peak of the Northern Hemisphere tropical cyclone season is non-existent, with scant activity in the Western and Eastern Pacific basins. The historic inactivity of 2007 appears to be on tap again for 2008.
News (08/25) The Northern Hemisphere has continued to lose considerable ground with respect to climatology. The departure from normal, currently at 91%, will accelerate during the next$ weeks unless explosive development occurs somewhere in the world. August and September typically see many major tropical cyclones (Cat 345) in several different basins. Tropical Storm $ supply much ACE since it was relatively week, although it lasted for a considerable length of time. Models are hinting that 94L (Gustav?) may become a powerful system during the next we$ News (08/16) The continued inactivity in the Western Pacific has finally caused the Northern Hemisphere ACE total for the calendar year 2008 to fall behind climatology. Last year (2007) at this time, the NH ACE value was 151.
News (08/11) Major Hurricane Hernan and weak Tropical Storm Kika have accounted for slightly less than the climatological NH TC ACE for the past week. As August progresses, approximately 6 units of ACE are typically expected each day. This rate requires at least one storm of Category 4+ activity each day.
News (08/05) The previous two weeks have been very quiet in terms of Northern Hemisphere Tropical Cyclone activity. The NH ACE from July 22- August 5 was 20. The average from 1970-2007 for this time period was 40, with 21 occurring in 2007. The tropics are rather quiet.
Old News (07/31) With July coming to an end, the Northern Hemisphere TC activity for the calendar year is near normal at 162, which is above climatology by the amount of ACE that Bertha contributed. The Western and Eastern Pacific basins are expected to remain below average and fall further behind climatology as August begins. Hurricane Dolly pushed Atlantic activity well above normal with nearly 60% of last year's activity already matched.
Old News (07/22) ACE in the North Atlantic has reached 1/2 of the ENTIRE year of 2007. This is largely due to record-length Hurricane Bertha. Since 1970, this is the second most ACE to date in the North Atlantic, only behind 2005. Using 1970-2007 past activity, current ACE is on average reached around September 3. However, one July storm does not mean a trend, and Northern Hemisphere activity overall is only slightly above normal. Continued below average activity is expected in the Pacific basins.
Old News (07/11) ACE has reached 100 for the calendar year in the Northern Hemisphere. Over the past 30 years, this is approximately 9 days ahead of climatology (July 20).