After a crazy and historical June, the Atlantic hurricane season has seemed to have calmed out. In July, we’ve had only one storm come through the Atlantic, Hurricane Elsa, back in early July and since it’s been quiet throughout.
So far, looking back at the month of July compared to the previous month of June, this month is looking to be a relatively calm one. But, according to the National Hurricane Center, the Climate Research Center, and data from previous seasons, don’t expect the rest of the season to be as quiet.
While July has remained a calm one, this is not too out of the ordinary. On average, when looking at every season since 1851, July tends to be a month where we see very little hurricane/tropical storm development.
In fact, when you crunch the numbers and look at the number of tropical storms and hurricanes from 1851 to 2017, July generates about 0.7 tropical storms and 0.3 hurricanes per year on average. When comparing it to other months in the season, July is only slightly above June and November for having the least amount of tropical storms and/or hurricanes generated on average.
One thing that should be pointed out is that differences between the averages of June, July and November are only slight, with tropical storm average only increasing about 0.2 on average in July. Hurricane average for July is pretty much the same for November, about 0.3 on average per month. November is the month that tends to generate the least of hurricanes, but only about 0.2 on average.
It’s not until August when the average number starts to increase where we jump to 2.3 tropical storms and 1.5 hurricanes per year on average. This increase in both tropical storms and hurricanes is due to a combination of seasonal and climatological changes and unfortunately, for this Fall, we will be experiencing both.
The biggest reasoning behind this is the gradually rise in sea temperatures during the summer. By late summer, water temperatures will be at their warmest and it will be enough to sustain tropical cyclogenesis, which is a water temperature of about 26.5 degrees Celsius. This peak in water temperature is usually observed between August to October.
Once the water out in the tropics and/or Atlantic reaches that fresh hold of 26.5 degrees Celsius, we could see more development of tropical storms and/or hurricanes into August and September. This is especially true off the coast of Africa where tropical depressions will have warmer waters, and longer durations, to develop into storms.
Another reason that we could see more development in August and September is the return of the La Nina climate pattern. For those who are unfamiliar with the cycle, the La Nina cycle is a natural Earth cycle marked by cooler seawater in the Pacific Ocean and where we see weaker vertical wind shear. It’s also an environment that induces less atmospheric stability in the Atlantic as well.
When put all together, La Nina could be a potential driver for more tropical storm development due to weaker vertical wind shear and less atmospheric stability. Combine that with the warmer waters in the Atlantic, we could see enhanced chances for the development of tropical storm/hurricane activity in the Atlantic.
The Climate Prediction Center has officially declared a “La Nina Watch” through September to November of this year, indicating that it is expected to return this Fall and last through the winter of 2021-2022. This Watch, unfortunately, takes place during the peak of the Atlantic Hurricane Season and during a time where storm development will be most favorable.
With these conditions in place for the rest of the 2021 Atlantic hurricane season, we could expect a busy fall once July rolls off the calendar. Only time will tell how bad the Atlantic hurricane season will get in August through September, but if history has taught us anything, don’t expect July to be like the others.
All Data used is from the National Hurricane Center and NOAA Hurricane Research Division. To see more information about the Atlantic Hurricane Season, please visit the National Hurricane Center for more information: https://www.nhc.noaa.gov/. If you wish to learn more about NOAA Hurricane Research Division and the research done, please visit the NOAA Hurricane Research Division to learn more: https://www.aoml.noaa.gov/hurricane-research-division/
All Information pertained about La Nina comes from the Climate Prediction Center. To see more information about the La Nina Watch, visit the Climate Prediction Center: https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/enso-alert-readme.shtml