Monthly Archives: December 2016

Hurricane Season 2016 Officially Ends, Higher ACE Index

From a record-breaking extremely strong El-Nino last hurricane season, the Atlantic, the EPAC and the Central Pacific this season all were above normal. This was pretty much forecast but Mother Nature fools forecasters all the time. A short summary of the season follows:

For the Atlantic,  2012 was the last time there was an above average season. The Atlantic saw 15 named storms during Hurricane season, 2016. Out of the 15 named storms, the Atlantic basin had 7 hurricanes Alex, Earl, Gaston, Hermine, Matthew, Nicole, and Otto. What surprised many is that out of those 7 hurricanes, 3 of which were major hurricanes – Gaston, Matthew, and Nicole.

Many were wondering would Florida be spared a hurricane this year. After all these years and true to form, Florida had two Tropical Storms – Colin and Julia, and finally, Hurricane Hermine made landfall in Florida, the first since Hurricane Wilma in 2005. The Eastern coast of the US also was battered with South Carolina having landfall with Tropical Storm Bonnie and Hurricane Matthew.

Speaking of Hurricane Matthew, it was the longest-lived storm in the Atlantic and it was also the strongest with maximum sustained winds of 160 MPH, a category 5. Hurricane Matthew made landfall at Haiti, Cuba, and the Bahamas but as a category 4 storm during  the trek of the Eastern Caribbean and the Atlantic.

Lest us not forget, there were other storms away from the US. Tropical Storm Danielle visited Mexico, Hurricane Earl in the Belize and lastly, very late in the season Hurricane Otto in Nicaragua.

So, how do we get a better feel of the hurricane season activity for this year? One method called Index. ACE Index is using a sum of the energy accumulated with all the cyclones (tropical storms, sub-tropical storms and hurricanes) that happened to form within the hurricane season. Calculating ACE is done by using the square of the the wind speed every six hours during the storm’s lifetime. Remember, a tropical depression is below 35 knots and it is not added. Hence, a cyclone that is longer lived will have a higher ACE indices verses a shorter lived cyclone which will have a lower ACE indices.  ACE indices of a single cyclone is windspeed (35 knots or higher) every six hour intervals  (0000, 0600, 1200, 1800 ) or ACE = 10kn2.

Total ACE:

\Sigma = \frac{Vmax^2}{10^4} \ \

* Vmax is estimated sustained wind speed in knots. *

An average seasonal ACE in the Atlantic is between 105 -115 or mean average of 110.

2016 Atlantic ACE
Tropical Cyclone Name
Max Wind Speed (in Knots)
ACE 10kn2
Alex *
75
4.1725
Bonnie *
40
0.1055
Colin
50
1.1350
Danielle *
40
0.4050
Earl
65
1.5450
Fiona *
45
3.0275
Gaston  105 24.2925
Hermine
70
3.0925
Ian
55
2.9575
Julia
35
1.2250
Karl
60
5.8150
Lisa
45
2.2600
Matthew
140
47.9950
Nicole
115
25.2075
Otto
95
6.1600
——–
ACE Total:
132.4350

Please note: Those with red asterisks have Tropical Cyclone Reports versus the Operational Advisories. The TCR’s are more comprehensive in detail. Those without the red asterisks will have the TCR’s in time. The ACE Index numbers may change with each TCR. I will try to update this post at that time.

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