• Bryan Norcross

Hurricane season is hanging on by a thread

A non-tropical low-pressure system off the Carolinas has a robust circulation. This is the storm that produced heavy rain, wind, and extremely high tides at the coast over the weekend. It’s now heading out to sea, so the weather is better. But tides will continue to run very high flooding low-lying coastal areas in the Carolinas and the Mid-Atlantic into tomorrow.

The weather system has a large circulation, so it’s pushing a lot of water toward the coast on its northern side. That combined with the King Tides – the extra-high tides caused by the seasonal alignment of the sun and the moon – is causing the flooding. Both effects will decrease by midweek.

The low-pressure system is heading out to sea, so feel free to ignore it. The National Hurricane Center, however, is monitoring it for possible tropical development. They give it a slight chance of losing its attached fronts and taking on at least some characteristics of a tropical system in a few days.

If by chance it becomes tropical enough to get a name, and has winds of 40 mph or higher, it would be named Adria – the first name of the overflow list that went into effect this year replacing the Greek letters.

The window for development is short. By the end of the week, the system is forecast to be absorbed by a North Atlantic storm.

This is all about keeping the modern record consistent. Now that we have super-high-resolution satellites and, essentially, radars in space to see hidden circulations, plus other monitoring and analysis tools, we count everything that fits the long-established criteria to be designated a system with tropical characteristics.

If you’re thinking that this makes it seem like there are more storms now than there used to be, you’d be right. The number of named storms in an average hurricane season is going up largely because monitoring and measuring technology has improved, unrelated to any changes in how Mother Nature is making tropical storms and hurricanes.

This means making simple comparisons between hurricane activity now versus 30 or 50 or 100 years ago must be done with care. Hurricane Season 1933 was extremely busy, for example. Likely rivaling 2020. But we didn’t count the storms in the eastern Atlantic because there were no satellites.

In terms of the hurricane threat, the biggest difference between anytime in the past and today is coastal development. When the powerful hurricanes of the first seven decades of the 20th Century hit the coast, there was nowhere near as much to damage or as many people to threaten.

In addition, of course, sea level is higher than in the last century, which makes minor flooding events a bit worse. Just six inches of higher water can cover a road, for example. But if a hurricane is producing a 10-foot storm surge, the slight water-level difference is less important.

The problem is that the sea level is getting relentlessly higher, which will eventually come into play in a more significant way during hurricane landfalls. Living along the coast is going to mean dealing with that reality.

For now, hurricane season continues to be functionally over for us. Welcome to fall.