Farewell to Fernand as the Atlantic Takes a Labor Day Holiday
Low chance of development with a tropical wave rolling off Africa next week, but significant development is unlikely
After a rollicking August, the Atlantic basin looks poised to go its longest stretch without a named storm since the last days of July.
Feisty Fernand clung to life with some help from the northern reaches of the Gulf Stream but finally crossed the Rubicon into the much cooler North Atlantic, losing all associated thunderstorms and shedding its tropical identity early Thursday over the open Atlantic.
Atlantic honoring the Labor Day holiday
It’s unusual for the Atlantic to go stormless over the Labor Day holiday, but that’s what’s shaping up for the upcoming weekend.
Hurricane season hits us in waves, with each wave into September typically bigger than the last. The first wave of activity came at the end of June and beginning of July when the first three named storms of the season formed between June 24th and July 5th.
Then things went dormant for about a month before Dexter formed late on August 3rd.
The second wave culminated of course with Hurricane Erin, the first hurricane of the season and the 4th earliest Category 5 ever recorded.
Now models suggest a brief intermission before the third wave.
Blame it on the MJO
These cycles of bunchy activity are tied to the phase of the Madden-Julian Oscillation or MJO, a see-saw pattern of upper-level winds that creates large regions of rising air and large regions of sinking air across the global tropics. This see-saw pattern moves eastward, circling the globe every 30 to 60 days on average.
When the rising branch is over or just east of the tropical Atlantic – as it’s been since the start of August- we tend to see increased activity. Once the rising branch moves out, it’s usually replaced by the sinking branch, which dries things out and ratchets up storm-busting wind shear as it passes through the basin. That’s where we find ourselves headed into September.
It’s worth stressing the MJO isn’t the end-all, be-all, and storms can (and often do) still form when the MJO isn’t in a conducive configuration, especially around the peak of the hurricane season when the atmosphere is generally much more conducive than it is in the early months of the year.
But the MJO is a performance-enhancing drug for the Atlantic, and we’re extra-wary when it coincides with the peak part of the season.
With the sinking side of the MJO over the Atlantic for the next few weeks, we don’t anticipate a significant burst of activity again until the rising branch passes through starting around the second week of September.
Longer range models generally agree, showing little in the way of organized activity for the next week or two.
Slim pickings for now
The National Hurricane Center has outlined the eastern Atlantic for a low chance of development next week with a tropical wave that’s expected to roll off Africa later this weekend.
Model guidance is wholly unimpressed with its prospects and most scenarios keep the disturbance weak and on a trajectory over the open Atlantic next week.
There’s a chance a depression or named storm comes of the system, but for now models don’t indicate significant development that would pose any threat down the line.
Otherwise, the only area we’ll be watching for next week is an unusually strong cold front dipping its toes into the warm waters off the southeast U.S. While sometimes low-pressure areas along cold fronts can morph into tropical systems, for now our models are keeping any storminess along this frontal zone non-tropical.
Ty Mr. Lowry 😃