Posted by
theoilpatchplug on Monday, October 29, 2007 2:03:51 PM
2007 Yearly Tropical Cyclone Activity to Date
Ryan N. Maue Cross Post at Climate Audit (h/t) Steve McIntyre Unless a dramatic and perhaps historical flurry of activity occurs in the next 9 weeks, 2007 will rank as a historically inactive TC year for the Northern Hemisphere as a whole. During the past 30 years, only 1977, 1981, and 1983 have had less activity to date (January-TODAY, Accumulated Cyclone Energy). However, the year is not over...
2007 lowest September activity on record since 1977
2006 and 2007 lowest October activity on record since 1976 and 1977
For the period of June 1 - TODAY, only 1977 has experienced LESS tropical cyclone activity than 2007.
There are currently two worldwide tropical cyclones: Tropical Storm Noel and Unnamed Arabian Sea TS...
On average to date (1970-2006), the Eastern Pacific season is 97% completed, Western Pacific 82%, North Atlantic 93% and overall Northern Hemisphere 87%.
Figure 1. can be permanently found at
2007 Tropical Activity Update (Climatology 1970-2006)
Historic Northern Hemisphere Inactivity During Summer and Early Fall
Figure 2. illustrates the number of tropical cyclone days since 1970 for the Northern Hemsiphere. It represents all storms of > 34 knots intensity during the calendar year (Jan-Dec). On average, an additional 40 tropical cyclone days are expected for the period of October 27 - December 31 (sigma of 16 days). The current departure from the long-term mean is 140 TC days. Approximately 70 tropical cyclone days occurred during the latter parts of 1984, 1992, and 1997.
Figure 2. Historical tropical cyclone days for the calendar year for the Northern Hemisphere including the Eastern Pacific, Northern Western Pacific, Northern Indian Ocean, Arabian Sea, and North Atlantic Ocean Basins. A storm must have at least 34 knot maximum sustained winds to be included. The red line marks the mean/median of a climatology constructed from 1970-2006 data. Data during the 1970s should be considered with caution. *** LARGER VERSION
Figure 3. Historical hurricane days for the calendar year for Northern Hemisphere (as in Fig 2) -- must be > 64 knots wind observations. For the remainder of the year, on average, 16 additional hurricane days have occurred. The most active years were 1984, 1990, 1992, and 1997 with > 30 additional H-days for Oct 27-Dec 31. The least active years typically see less than 10 H-days including 1999 and 2000 (8 H-days) and 1973 (0 H-days).
Accumulated Cyclone Energy Plots
NORTHERN HEMISPHERE JUNE 1 - NOV 30 ACE
NORTH ATLANTIC *** WEST PACIFIC *** EAST PACIFIC ***
Hurricane Ioke of 2006 accounted for 15% of overall Northern Hemisphere TC ACE
Currently, the North Atlantic Basin accounts for 20% of the overall Northern Hemisphere Activity
TC Climatology Trivia
Previous years with exceptionally weak ACE activity (to date: October 29, 00Z)
Link: Tab delimited file of % departure from 1970-2006 Mean to date.
Format of Tab file: EPAC, WPAC, NH, NATL
Sorted Historical Departures [% from 1970-2006 mean to date]:
***EPAC ***WPAC ***NH ***NATL
1983 saw a couple powerful typhoons in the Western Pacific in November. 1977 similarly had several late season typhoons. In the Eastern Pacific, 1983 was very active in October and November with 3 Major Hurricanes. Raymond had a particularly long track. The Atlantic season saw no October activity in 1983.
Link: ACE June 1 - November 30, 1970-2006 for each basin
Power Dissipation Index (Emanuel 2005)
PDI is simply the cubic version of ACE with considerably more weight to more intense storms.
2007 PDI Departure from Climatology (thru October 29, 00Z) **** Current PDI (climo PDI)
Northern Hemisphere = -26% **** 29739 (40288)
North Atlantic = -10% **** 6555 (7282) Effects of the Category 5's
Eastern Pacific = -64% **** 3875 (10704) Historic inactivity
Western Pacific = -21% **** 17200 (21783) To date, very anomalous
PDI Distribution Climatology (scaled)
Distribution (1944-2007) of PDI per storm: 1% [1.72] ** 3% [2.32] ** 5% [3.0] ** 10% [4.1] ** 25% [8.8] ** 50% [28.3]
75% [103] ** 90% [216] ** 95% [326] ** 98.5% [504] ** 99% [552] ** Max Ivan [859]
Text File of climatological PDI for each day (values are PDI)
Text File of the % to date of PDI [EPAC, WPAC, NORTHHEMI, NATL] 
Other Notable World Tropical Cyclones and PDI
Hurricane / SuperTyphoon Ioke 2006 (927)
SuperTyphoon Chaba (WPAC) 2004 (752)
Hurricane Linda (EPAC) 1997 (363) Category 5, strongest on Record
SuperTyphoon Tip (WPAC) 1979 (695) Category 5, lowest ever recorded MSLP of 870 mb
Pre-1944 Notable Hurricanes and PDI
New England Hurricane 1938 (421)
Hurricane 13 of 1936: Landfall North Carolina (297)
Hurricanes 11, 12, 13, 18 of 1933: (198, 213, 236, 234)
Freeport Hurricane of 1932 (55) very rapid pre-landfall development
Cuba Hurricane of 1932 (429)
Bahamas Hurricane of 1932 (447) Category 5
Lake Okeechobee Hurricane of 1928 (537) Category 5
Great Miami Hurricane of 1926 (429) Category 4.9
Hurricane 4 of 1926 (680) Long Cape Verde 22 days duration
Hurricane 2 of 1922 (432) Bermuda
Florida Keys Hurricane of 1919 (447)
Galveston Hurricane of 1915 (325)
Hurricane 3 of 1915 (433) no landfall
2007 North Atlantic Season storm PDI
Andrea 2.3 (Subtropical)
Barry 3.4
Chantal 2.5
Dean 386
Erin 1.3 (weak weak weak)
Felix 215
Gabrielle 4.0
Humberto 8.2
Ingrid 2.8
Jerry 2.4
Karen 17.2
Lorenzo 6.7
Melissa 1.9
ACE (Bell et al. 2000) Climatology
Text File of climatological ACE for each day (values are ACE)
Text File of the % to date of ACE [EPAC, WPAC, NORTHHEMI, NATL]
Climatological North Atlantic ACE during calendar year
Northern Hemisphere Plot
Eastern Pacific Plot
Western Pacific Plot
Climatology based upon ACE (Bell et al. 2000) from 1970-2006 for each basin. ACE is not a perfect metric and does not account for storm size. Northern Hemisphere includes Northern Indian Ocean after 1976, which accounts for less than 3% of the yearly total. Data quality is a tremendous issue. The NHC declared extratropical observations were not included, which can account for up to 20% a year in additional ACE. The JTWC only started keeping track of EX phases in 2004, so there are literally 1,000 observations since the 1950s that are likely extratropical in the database (as phished out from the JMA database).