As I write this story, Tropical Storm Phillipe is headed westward across the Atlantic basin. According to the National Hurricane Center, the storm is expected to weaken by Friday. If you are keeping count, Phillipe is the sixteenth named storm of the Atlantic hurricane season. There are only twenty-one names on the list. Will all of the names on the 2023 list be used? Perhaps.
The National Hurricane Center is currently monitoring another system that has a 70 to 90 percent chance of developing over the next two to five days. If it becomes a tropical storm and/or hurricane, it will be named Rina. The same namelists are used every six years unless a name is retired due to its severity or impact. According to the National Oceanic and Atmospheric Administration website, “They are now maintained and updated through a strict procedure by an international committee of the World Meteorological Organization.”
So what happens if more than twenty-one storms are named this year? The NOAA website goes on to say, “In the event that more than twenty-one named tropical cyclones occur in the Atlantic basin in a season, or more than twenty-four named tropical cyclones in the eastern North Pacific basin, any additional storms will take names from an alternate list of names approved by the WMO for each basin.” This is a change from the recent past when the Greek alphabet was employed. This change was made because experts believed that certain Greek letter names were too indistinguishable and may cause confusion.
Additionally, there has been an uptick in the number of seasons that exhaust the name list. This makes it challenging from a historical or climatological perspective if, for instance, there are two Hurricane Etas. The only two years in which more than twenty-one named storms happened are 2005 and 2020, respectively. In other words, this is a problem that has reared its head only within the last two decades. With almost half of the Atlantic hurricane season still in front of us, 2023 could join this infamous list. I think it is a possibility, but only time will tell.
Better observation technonology and understanding are likely factors in the uptick of named storms, particularly some of the smaller and subtropical systems. However, please do not misuse that statement to discount climate change. I highly recommend the NOAA GFDL global warming-hurricane website for the latest information on relationships between tropical cyclones and climate change. For the Atlantic Basin, the page cautions, “….It is premature to conclude with high confidence that human-caused increases in greenhouse gases have caused a change in past Atlantic basin hurricane activity that is outside the range of natural variability, although greenhouse gases are strongly linked to global warming.”
While the literature cautions about frequency of hurricane activity, it also states, “Some possible emerging human influences on past tropical cyclone activity…for the Atlantic, recent increases in rapid intensification probability, aerosol-driven changes in hurricane activity, and increases in extreme tropical cyclone precipitation in some regions.” Studies also note that globally, the fraction of high intensity storms have increased as well as the latitude of maximum intensity.
As we enter the month of October, hurricane breeding grounds tend to shift from the Main Development Region of the Atlantic basin to the western Atlantic, Caribbean Sea, and Gulf of Mexico. However, the water temperatures continue to run hot in the Atlantic basin so I will continue to watch every corner for development. The season technically ends in November 30th, but the past twenty years have shown us that old norms no longer apply.
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