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Hurricane ACE Data For 2014

January 2, 2015

By Paul Homewood  


Dr Ryan Maue has now updated his ACE data to the end of December 2014.

Just a quick recap for those not familiar, Accumulated cyclone energy (ACE) is a measure used by the NOAA to express the activity of individual tropical cyclones and entire tropical cyclone seasons. It uses an approximation of the wind energy used by a tropical system over its lifetime and is calculated every six-hour period. The ACE of a season is the sum of the ACEs for each storm and takes into account the number, strength, and duration of all the tropical storms in the season.

The ACE of a season is calculated by summing the squares of the estimated maximum sustained velocity of every active tropical storm (wind speed 35 knots (65 km/h) or higher), at six-hour intervals.




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It has been a quiet season in the North Atlantic and Western Pacific, but this was offset by the Eastern Pacific. Globally, however, Accumulated Energy was about 10% below normal.

[N.B  The SH total of 198 is for Oct 2013 – May 2014, as that is the season there. The calendar year figure is 132, which is what the total of 700 is based on].





In terms of number of hurricanes, totals of all hurricane categories has been declining since the 1990’s, though the number of major ones has been fairly stable.





Similarly, we see that the Accumulated Energy has also been dropping since the 1990’s, particularly in the Northern Hemisphere.





WeatherBell Models!prettyPhoto

One Comment
  1. January 3, 2015 3:31 am

    Thanks, Paul.
    Yes, 2014 is over. It was good in relation to hurricanes, not good with typhoons.
    But 2015 looks more active in the Atlantic …..

    The Tropical Meteorology Project:
    (Dr. Philip J. Klotzbach, Dr. William M. Gray. Colorado State University – CSU)

    Qualitative Discussion of Atlantic Basin Seasonal Hurricane Activity for 2015
    (.pdf, 11 December 2014):

    We are providing a qualitative discussion of features likely to impact the 2015 Atlantic basin hurricane season rather than a specific numbers forecast. This outlook for 2015 will give our assessment of the probability of four potential scenarios for Net Tropical Cyclone (NTC) activity.

    We have developed a new way of assessing next year’s activity in terms of two primary physical parameters:

    1. the strength of the Atlantic thermohaline circulation (THC)
    2. the phase of ENSO

    We believe that we are still in an active era for Atlantic basin tropical cyclones since 1995 (despite the quiet seasons that occurred in 2013-2014), and we expect that typical conditions associated with a positive Atlantic Multi-Decadal Oscillation (AMO) and strong thermohaline circulation (THC) will return in 2015. One of the big challenges for 2015 is whether or not the currently developing weak El Niño will persist through the 2015 hurricane season. While we saw a significant weakening of the Atlantic Multidecadal Oscillation (AMO) and thermohaline circulation (THC) during the spring of 2014, North Atlantic SST and sea level pressure patterns have since rebounded to conditions characteristic of an active era. We anticipate that the 2015 Atlantic basin hurricane season will be primarily determined by the strength of the THC/AMO and by the state of ENSO.

    For the 2015 hurricane season, we anticipate four possible scenarios with the probability of each as indicated:

    1. THC circulation becomes unusually strong in 2015 and no El Niño event occurs (resulting in a seasonal average net tropical cyclone (NTC) activity of ~ 180) – 10% chance.
    2. THC continues in the above-average condition it has been in since 1995 and no El Niño develops (NTC ~ 140) – 40% chance.
    3. THC continues in above-average condition it has been in since 1995 with the development of a significant El Niño (NTC ~ 75) – 40% chance.
    4. THC becomes weaker and there is the development of a significant El Niño (NTC ~ 40) – 10% chance.

    Typically, seasons with the above-listed NTC values have Tropical Cyclon activity as follows:

    180 NTC – 14-17 named storms, 9-11 hurricanes, 4-5 major hurricanes
    140 NTC – 12-15 named storms, 7-9 hurricanes, 3-4 major hurricanes
    75 NTC – 8-11 named storms, 3-5 hurricanes, 1-2 major hurricanes
    40 NTC – 5-7 named storms, 2-3 hurricanes, 0-1 major hurricane

    Thermohaline Circulation (THC) – A large-scale circulation in the Atlantic Ocean that is driven by fluctuations in salinity and temperature. When the THC is stronger than normal, the AMO tends to be in its warm (or positive) phase, and more Atlantic hurricanes typically form.


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