Sorry for the late start to the 2015 Atlantic Hurricane season blog here at CajunWX. But with two moves and a new house over the past several months, time has been at a premium. Now that we have somewhat settled into our new home in coastal south-central Louisiana, it is time to do some prognosticating and catching up about the 2015 season. While I concentrate on systems which have a potential to influence the Gulf of Mexico and especially those threatening the Louisiana Gulf Coast, it is always good to look at the broader Atlantic Hurricane Basin when considering potential season intensity.
Those who have read my previous prognostications, know that I prefer to do my own analysis of the factors influencing the season then compare those predictions to the predictions made by the major tropical weather outlets. I am the first to admit these agencies have both greater assets and knowledge than yours truly. But it is fun to take a stab at the predictions myself and see who comes out best at seasons end.
You can find detailed explanations of the current El Nino/La Nina (ENSO) forecast, the Madden–Julian oscillation (MJO), oceanic sea surface temperatures, Sahel rainfall amounts, and all of the other major predictors on numerous sites. I am not going to get deeply into any of them here. It can get very complex and is not what most people are most concerned with. They want to know what to expect, more than why, But rest assured all those listed above and many more have been reviewed for this forecast.
This year it appears the two major factors affecting the Atlantic season will be the intensity of the forecast El Nino and the significant amount of potential Accumulated Cyclone Energy (ACE) in the Gulf and Atlantic Basin. In the end, it appears we will have a 2015 season which falls below average. Here are the predictions from the major sites I tend to rely on as well as my overall thoughts:
AVG | CSU | NOAA | WxChannel | WeatherBELL | CajunWX | |
Named Storms | 12 | 8 | 6-11 | 9 | 7-9 | 8 |
Hurricanes | 6 | 3 | 3-6 | 5 | 3-5 | 4 |
Cat 3 + Hurricanes | 3 | 1 | 0-2 | 1 | 1-2 | 1 |
Total ACE | 92 | 40 | 60-80 |
So what does all that mean? Basically, there will only be about two-thirds of the named storms we have seen in hurricane seasons over the past several decades. Good right? Yes! And no!
While fewer storms are always a good thing, we also have to look at where those storms are more likely to form and make landfall. For instance, there were eight named storms, six hurricanes and two major hurricanes last season. Not far off the predictions for this year, but in 2014 the Atlantic seaboard got only a glancing blow or two with no impact on the Gulf states. Back in 1992, there were seven named storms, four hurricanes and only one major hurricane. The big one was named Andrew and caused $26 million in damage in Florida and Louisiana. Forever proving the National Hurricane Center mantra “It only takes one!”
Will we have another Andrew this season? Probably not. But we just don’t know. One of the things that is a bit concerning to me is has to do with the ACE index. The ACE Index for a season is the sum of the ACEs for each storm that occurs and takes into account the number, strength, and duration of all the tropical storms in the season. While the ACE for the basin as a whole is predicted to be below normal by up to 60%, as noted above, that is just an average. It can change for particular regions.
This season, it appears that the region from the Cape Verde Islands well into the Caribbean Sea will only account for about 25% or less of the total ACE. Yet according to the WeatherBELL predictions, the ACE for the Gulf Coast and Atlantic Seaboard will account for 75% of the total ACE and the area from Sabine Pass to Cape Hatteras a full 50% of the seasons total ACE. Bottom line, while we will likely see fewer systems than normal, they will likely not all turn out to sea like last year. Also of concern is the best “analog year” for this season. According to those who track such things, this season will be most like 1957 overall. That is the year Audrey struck western Louisiana.
Looking at the two storms thus far this year, it appears these predictions may be on target. Ana formed in early May and raked the Atlantic Seaboard from Myrtle Beach, South Carolina northward with 60 mph winds and Bill nearly reached hurricane strength before making landfall near Matagorda Bay, Texas, and retained depression status all the way into Oklahoma.
So yes it will be a quieter than normal Atlantic season, but I look for the Gulf Coast and Atlantic Seaboard to see another landfalling storm or two. If one of those happens to be a major hurricane, it will be that one storm the season is known for forever, not that we hand only a handful or so of named storms. As always, stay alert and ready for whatever the tropics may throw your way. And if you are looking for insights on the Gulf systems, follow CajunWX for updates.