Disclaimer: This site is not affiliated with the National Hurricane Center, Hurricane Hunters, Storm Prediction Center, or National Weather Service. ALL forecasts herein are the result of my analysis, and I am solely responsible for the content. As always, follow the NHC and Local NWS office guidelines, and your local Emergency Management officials for emergency decisions.
(T. F. “Storm” Walsh III)
For those who have donated to my site, your help has been greatly appreciated. For those not aware, donations to my site help me offset my out of pocket expenses…such as some of the model maps you view on here, which are only available due to my subscription to the corresponding sites. The F5 Data maps I post as well, is another out of pocket expense (monthly subscription). Updates to software (weather related), and costs for my domain name are also out of pocket to me. To donate, please click the DONATE button to the right. Any help you provide is immensely appreciated! Without your help, I may not be able to continue paying the monthly subscription charges for access to all of the best information I use in my forecasts.
This is an update to all previous 2018 Hurricane Season outlooks posted. I have cut out some graphics in order to make this easier to follow. This seasonal forecast will most likley require another update, as we see how forecast conditions and actual conditions pan out. This forecast is based on the most recent updates available from various climate modeling, therefore, some variables COULD change.
The following factors will be important players on the field in determining how busy the season could be:
Gulf of Guinea anomalies
Indian Ocean Dipole
Based on analysis of the most current updates in climate modeling, the “consensus” still calls for ENSO neutral conditions for the 2018 Atlantic Hurricane Season. Analysis today of the climate models reveal the majority of modeling still indicates trend toward neutral “warm bias” ENSO forecast conditions. The following are the climate modeling Nino 3.4 plumes, from three of the analyzed models.
The following is a breakdown of ALL of the climate models, average of the dynamic modeling, average of the statistical modeling, and average of ALL of the models combined.
I would like to point out IRT the ECMWF NINO 3.4 plumes, that the ECMWF was adamant in developing an El Nino last hurricane season. The following graphic, from Dr. Phil Klotzbach’s presentation at the 2018 National Hurricane Conference, indicates what actually occurred:
ECMWF 2017 ENSO PLUME FORECAST
The Atlantic Ocean is currently in a weak positive AMO at the moment, with SST anomalies showing cooling since Jan. 01, 2018
JAN. 01, 2018
APR. 05, 2018
At the moment, this is one of the uncertainties, as to whether or not the SST anomalies will become warmer. The ECMWF indicates SST anomalies to be at average during JAS, with warmer anomalies north of the MDR. The CFSv2 indicates about the same, except warmer anomalies extend a little further south. It is to note, that the CFSv2 showed much the same anomaly pattern last season, however we did see warmer SST anomalies develop over the MDR.
ECMWF SST ANOMALY FORECAST
The MSLP anomalies from the ECMWF are forecast to be near or at average during JAS
ECMWF MSLP ANOMALIES
GULF OF GUINEA
2012 GULF OF GUINEA COLD ANOMALY
IRT the Gulf of Guinea: The SST anomaly forecast calls for a possible cooling in the Gulf of Guinea. This generally plays a role in rainfall over Guinea, or in some cases, rainfall over the West African Sahel region. Let’s look at the 2016 and 2012 hurricane seasons. The Gulf of Guinea was pretty much showing warmer anomalies in 2016. A warmer Gulf of Guinea, in general, keeps the ITCZ pretty much suppressed further south over the African continent. This causes the Sahel region to remain drier with average or below average rainfall. Given the pressure gradient created by colder anomalies in the Gulf of Guinea (as in 2012 shown above), in relation to the hotter African continent (higher pressure now over the Gulf of Guinea, lower pressures north), the ITCZ is pushed further north, and can reach into the Sahel region. This allows for more rainfall over the Sahel, which in turn helps to cut down on SAL outbreaks and their severity. This increases the chance of a greater number of tropical waves, and an increase in intensity of these waves. Hence, an added possibility of an above average season.
Based on analysis of the NCEP-CFSv2 climate model, the model has been consistent in forecasting slightly below, to below average wind shear over the Atlantic basin for the duration of the 2018 hurricane season. This is another favorable indicator for the season.
CFSV2 ATLANTIC u200-u850 (WIND SHEAR) FORECAST
A little less looked at, or less mentioned phenomenon, is the Indian Ocean Di-pole.
The IOD (Indian Ocean Dipole), (to my understanding from previous readings) has an effect on the WAM (West African Monsoon) circulation, in that a negative IOD has the tendency not to disrupt the WAM, which plays a part in rainfall, and anomalous westerly surface winds at near 10N latitude. We did observe the WAM a few times near the peak of the 2017 season, however if my understanding of this feature is correct, the WAM is more pronounced during a negative IOD. The 2017 season witnessed a “neutral” to “positive” IOD phase. The current forecast indicates the IOD may now go negative, during the “busy” portion of the 2018 hurricane season. This could be positive factor for an above average season, if the forecast is correct.
The following link is a breif article on the WAM:
Positive: cooler in the tropical eastern Indian Ocean and warmer in the tropical western Indian Ocean.
Negative: warmer in the tropical eastern Indian Ocean and cooler in the tropical western Indian Ocean.
IOD FORECAST FEB 25, 2018
CURRENT IOD FORECAST
Based on the premise of more slightly positive, to positive forecast factors, vs negating factors, my official 2018 hurricane season outlook is updated as follows:
TOTAL STORMS: 14-16
MAJOR HURRICANES: 3-4
I have lowered the “high end” somewhat, given the fact that one must remember, based on the forecast data, we will be transitioning from colder to warmer conditions, based on the ONI (Oceanic Nino Index) trends as indicated by the graphic titled MODEL BREAKDOWN. I took these forecast statistics, and analyzed the ONI.
CURRENT ONI CHART
Based on the ONI trends and values, I had to disagree with Dr. Klotzbach on a couple of his analog years, and I chose the following which appear to come the closest to the trend (s): 1996, 2001, 2006, and 2012. I did go back a little further, prior to the active period which began in 1995, and figured in 1976 in a part of my calculations. Based on the other forecast parameters mentioned, and the ONI analysis, the “average” calculated out to 14 to just slightly above 14 for total storms, 7.5 to 8.25 on the hurricane total, and 3 to 3.5 on the major hurricane total. Again, I wish to reiterate, if conditions prove to be pretty much as thought, we should see the lower end of my forecast. IF conditions become more positive (i.e. regarding the IOD, Gulf of Guinea, and a more below average wind shear), we could see the higher end of the forecast, as 2 of the analog years I have chosen indicated 15 total storms in 2001, and 19 total storms in 2012.
Again, as new data is published, and I can see how actual conditions are playing out as we get into the season, I will most likely publish another update.
Have a blessed weekend!
T. F. “STORM” WALSH III
GMCS, USCG (ret)
METEOROLOGIST / HURRICANE SPECIALIST /SEVERE WEATHER SPECIALIST
MEMBER WEST CENTRAL FLORIDA AMS