Alexandra Cranford / WWL Eyewitness News Forecast Team
A weekly discussion of the tropics from the Eyewitness News Forecast Team
The tropics are quiet… very quiet. The only area that warrants any discussion in the Atlantic Basin is Invest 98, a spot of low pressure outside the Caribbean Sea. Strong shearing winds are tearing this system apart. It’ll be almost impossible for Invest 98 to get its act together in the next several days.
That means we have yet another week without any tropical threats in the New Orleans area.
And that’s been the dominant theme throughout this 2013 hurricane season. In fact, we’ve only had two hurricanes this season (Humberto and Ingrid made it to Category 1). Only eleven named storms have formed up so far. And we’ve had zero major storms of Category 3 or higher.
The storms that have managed to develop have been remarkably weak. The total energy of this season’s storms (known as Accumulated Cyclone Energy, or the ACE index) is the lowest we’ve seen in 30 years.
Why has this season been so quiet?
It’s an interesting question, because there are a bunch of factors that should create an active season. Here they are:
1. Atlantic waters have been fairly warm, and they got warmer earlier than usual this year.
2. There’s no El Nino. El Nino normally hampers hurricane development, but going into this season we couldn’t expect any protection from it.
3. We’ve been in an active hurricane cycle since 1995. That’s a stretch of 18 years that have brought higher than normal tropical activity.
These were the factors that influenced the aggressive pre-season forecasts. But it turns out those weren’t the factors that really mattered in terms of creating an active versus quiet season. Instead, these are the factors that dominated the Atlantic Basin and brought about our relatively tranquil conditions:
1. Those warm temperatures at the sea surface were also present farther up in the atmosphere, so the air was fairly stable. The lack of instability kept storms from forming up and swinging into full gear.
2. A ton of dry air over the Atlantic Ocean ate up a lot of systems. That dry, dusty air from the Sahara Desert spread as far west as Texas this season.
3. We’ve had an abundance of strong shearing winds aloft. Those winds knocked down any storms that tried to grow upward in the atmosphere and mature into strong, healthy tropical systems.
So while the ingredients were present for both an active and a quiet season, the quiet season ingredients are winning out.
From now until the end of November, the average outlook is another two named storms and a single hurricane. It’s possible we could add a couple more names to our list.
But things are looking quiet for a while. During the next couple of weeks, strong winds will be in control of the usual formation zones. That’s pretty typical for this point in the season.
And of course, the potential for storms will be decreasing as we head toward the official end of the season on November 30. On average, a slim 5 percent of a season's total storms form in the month of November.
See you back here next week for your Talkin' Tropics discussion. Every week, we'll post a fresh tropics forecast for the week ahead.