Historic Hurricane Delta – October 7, 2020


The 2020 hurricane season in the Atlantic Ocean has been a very active one, seeing 25 named storms (the average for a season is 12). And it’s still not over, as the season doesn’t officially end until November 30th. Hurricane Delta, currently churning in the Gulf of Mexico, is the earliest that a Greek name has ever been used for a storm in a calendar year. From Monday to Tuesday, Delta grew from a tropical depression to a whopping category 4 hurricane – in a matter of only 30 hours! It is the quickest increase in sustained wind speeds (increasing by 85 mph) in one day by a storm this year and the strongest Greek alphabet storm in history.
When it hits the Gulf Coast, Delta will be the 10th named storm to make landfall in the continental US, the most in one year! Unfortunately, yet again, Louisiana is going to take the brunt of the storm – for the fourth time this year – setting a record for the most hits in the state in one season.
For storms to form in October, you need the right ingredients: low wind shear and warm waters. More on wind shear here: https://www.weather.gov/ilx/swop-springtopics
Typically, the area with the “right stuff” this time of year is the western Caribbean, especially now as surface ocean temperatures there are 2 – 4 degrees Fahrenheit above average. But another important variable is the ocean heat content, or, the measure of available energy for a storm to use. The more warm water you have deeper down (not just at the surface) the more energy (fuel) you have for the storm. Imagine warm water at the surface, but there’s cooler water just below that gets churned up in a storm – that cold water can dampen the intensity of that storm. But if the water warm extends for many meters below the surface, you have a sustained fuel source to rapidly intensify a storm.
As the planet continues to warm, experts expect storm intensification to happen more often, and storms to become stronger and wetter on average.
“Our confidence continues to grow that storms have become stronger, and it is linked to climate change, and they will continue to get stronger as the world continues to warm,” says James Kossin, an atmospheric scientist at the National Oceanic and Atmospheric Administration.