For many late May and early June is the kickoff for summer. Many people will be traveling to the beaches from the southern tip of the Texas coast to the New England coastline. Also people will be going to other countries to see relatives or vacation. However, June is the official start of the Atlantic Hurricane Season. The Atlantic Hurricane Season runs from June 1st to November the 30th. Although storms have been known to form outside of the season. In an average year the Atlantic Basin will see 11 named storms, 6-7 becoming hurricanes, and 2-3 become major hurricanes (categories 3,4 and 5). Moreover, an average hurricane season will have an ACE (Accumulated Cyclonic Energy ) value of 90-100. ACE looks at how much energy a storm produces based on the storm’s intensity and longevity.
Average named storms per month
June- 0 (though storms have been known to form in June)
July- 1 named storm.
August- 2 named storms
September- 4 named storms
October-3 named storms
November-1 named storm
Climatology August, September, October, and sometimes November are the most active months. The peak of the Hurricane season is Mid August-late October. So the question is what type of Hurricane Season are we going to have for 2017? Before I answer that, I think it is a good time to talk about the naturally occurring weather patterns, El Nino, La Nina, and Neutral. To meet the Criteria a pattern must be persistent for 3 or more months in the Equatorial Pacific.
El Nino is when the Equatorial pacific water temps are 0.5 degrees Celsius or warmer for at least 3 months. Typically El Nino causes the Atlantic Ocean temperatures to be below average. It also causes strong shearing winds across the Atlantic. Thus, El Nino’s favor less hurricane activity in the Atlantic Basin.
La Nina is when the Equatorial Pacific water temps are -0.5 degrees Celsius are cooler for at least 3 months. La Nina causes the Equatorial Pacific water temps to be below normal. However, La Nina causes water temps in the Atlantic Basin to be above average. Also, strong shearing winds are less present. This favors an increase in hurricane activity for the Atlantic
Neutral is when El Nino or La Nina are not present. Water temps in the Equatorial Pacific are between -0.5-0.5 for at least 3 months. Basically the water temps are near average. Neutral tends to favor average to slightly above average activity in the Atlantic Basin.
Here is what I am thinking for the 2017 Atlantic Hurricane Season. Keep in mind one named storm has already formed. Arlene back in late April. I’m thinking we are going to have close to an average season if not slightly above average.
10-14 named storms
5-7 Hurricanes
2-3 Major Hurricanes
Last years forecast went well due to La Nina developing near the peak of the season. 2016 had 15 named storms, 7 becoming hurricanes, 4 major hurricanes, and an ACE value of 140. La Nina faded in March 2017. Since March 2017 we have been in the Neutral phase. As of this writing the water temps in the Equatorial Pacific have been around 0.4 degrees Celsius above average. That is still in the Neutral pattern. So how did I come up with my numbers for 2017?
I looked at water temps, the likely hood of El Nino developing, and past history. Confidence is growing that El Nino will develop sometime this year. NOAA has given the probability of an EL Nino forming 50-60%. When the El Nino forms will be key to what type of season with have. If it forms earlier than expected it could lessen hurricane activity. As a result I would expect the number of storms to be on the low end of my prediction. If El Nino forms later in the year than we could still have an above average season. While water temps are slowly warming in the Pacific they have yet to go past 0.5 degrees Celsius above average and stay there. In addition, so far water temps in the Atlantic Basin have not yet begun to cool like an El Nino pattern. In fact, the water temps are pretty close to average indicating a Neutral pattern is still in place. If El Nino does develop it would mean 2017 is a transitional year as we would be coming off a La Nina event. I looked at past seasons that have gone from La Nina to El Nino. The results have been based on when the El Nino develops
2009 Hurricane Season. In 2009 conditions begin to change from La Nina (October 2007-2008) to an El Nino type pattern. Neutral conditions were present in Spring. However, El Nino developed earlier than expected for the 2009 season. The 2009 Hurricane season was below average with 9 named storms, 3 becoming hurricanes, and 2 major hurricanes. El Nino rapidly developed and by summer was at its peak. This suppressed hurricane activity in the Atlantic
2006 Hurricane Season. In 2006 conditions started to change from La Nina (2004-2005) to El Nino. But Neutral conditions persisted for much of the summer. El Nino did not develop until the fall of 2006. Since El Nino developed later, the 2006 season was pretty much close to average. A total of 10 named storms formed, 5 became hurricanes and 2 became major hurricanes.
2002 Hurricane Season. In 2002 an El Nino developed but not till October. For the most part Neutral conditions were persistent for most of the 2002 Hurricane Season. The 2002 Hurricane Season was less active than the previous 3 seasons but overall slightly above average with 12 named storms forming. Since El Nino developed in the later part of the Hurricane season it allowed for a near to slightly above average season.
1997 Hurricane Season. 1997 saw conditions rapidly change from a strong La Nina (1995 & 1996) to a strong El Nino. El Nino formed in the spring of 1997. The 1997 season was below average with 8 named storms forming , 3 became hurricanes, and only 1 reached major hurricane status. The strong El Nino caused the Atlantic water temps to be below average and increased wind shear.
So looking at past history the key is when El Nino forms. If El Nino forms earlier the Atlantic hurricane season has seen less storms. If it forms later in the Atlantic Hurricane season the trend is to be near average in activity. No matter how many storms form remember it only takes 1 storm to make it a bad year. While us forecasters can predict how many tropical storms or hurricanes will form. It is nearly impossible to forecast when and where they will make landfall. You always need to be prepared and take watches as well as warnings seriously.
As I stated it only takes 1 landfalling storm to make it a destructive year. For example, 1983 was a way below average season with only 4 named storms forming. However 1983 was destructive due to Hurricane Alicia. Hurricane Alicia formed off the Texas coastline. The Hurricane rapidly intensified to a category 3 hurricane before making landfall near the Houston Metro area with 115 mph winds. Alicia cost $3 Billion dollars worth of damage. In 1992 only 7 named storms formed. Yet 1992 is when hurricane Andrew made landfall. Andrew made landfall in Florida as a category 5 hurricane then Louisiana as a category 3 hurricane. Andrew did $26.5 Billion dollars worth of damage and over 50 people perished. 2010, was way above average with 19 storms forming due to a strong La Nina. The US was spared landfalls. But for Canada and the Caribbean it was a different story. Hurricane Igor decimated the Canadian coastline causing serious damage to New Foundland. In November of that year Hurricane Tomas made landfalls in Grenada and Haiti doing serious damage and causing lots of deaths. Thus, it is best to be prepared.