WEATHER NEWS: Did forecasts of an extra-busy hurricane season turned out dead wrong?
In May, the National Oceanic and Atmospheric Administration released an outlook calling for the seventh above-average Atlantic hurricane season in a row. Like many experts, NOAA argued that an “ongoing La Niña,” combined with “above-average Atlantic temperatures [would] set the stage for busy season ahead.”
For the first time since 1997, August has passed without a single named Atlantic storm. In fact, through Wednesday, the basin was silent since the demise of short-lived Colin on July 3. It’s the first time since 1941 there were no named storms between July 3 and Aug. 30.
NOAA wasn’t alone in its predictions. Far and wide, experts agreed. At Colorado State University, hurricane researchers called for a nearly 50 percent chance that a major hurricane would strike the U.S. coastline (which could still happen). As recently as Aug. 21, AccuWeather published an article reading “the forecast for the number of hurricanes remains unchanged,” still calling for six to eight hurricanes and up to five major hurricanes.
While it’s unclear what the rest of the season will hold, it’s obvious that initial predictions aren’t exactly panning out. Some forecasters are defiantly remaining onboard what some consider a sinking ship; others are shifting their forecasts or admitting defeat. And experts underline that even one significant storm could have devastating consequences.
“It is fairly apparent that the Atlantic Tropical activity will clock in below average … the question now is by how much,” tweeted Mike Chesterfield, director of weather presentation at the Weather Channel. “What a bust of a forecast…..”
“We’re really facing a 2013-level seasonal hurricane forecast bust for the 2022 Atlantic,” echoed Sam Lillo, an atmospheric scientist at DTN Weather.
And while there are three systems to watch in the Atlantic, including newly named Tropical Storm Danielle, many are still wondering what’s behind the dearth of activity.
Fortunately, experts have some insight.
Why is the Atlantic so quiet?
Heading into the summer, many meteorologists pointed to an ongoing La Niña — a chain-reaction atmospheric process that begins with cooler waters in the eastern tropical Pacific — as an expected driver of above-average Atlantic activity. The cooler Pacific fosters subsidence, or sinking air, there, which makes it easier for air over the Atlantic to rise and form storms. La Niña also weakens disruptive high-altitude winds over the Atlantic, creating a friendlier environment for tropical development.
But something was missing: moisture at the mid-levels. Dry air 10,000 to 20,000 feet above the ground shredded any thunderstorm clusters that did crop up.
“The missing ingredient that kept tropical waves from developing as they normally do in August was unusually dry air in the mid-levels of the atmosphere … just north of the central and eastern sections of the Atlantic’s Main Development Region,” wrote Ryan Truchelut, an atmospheric scientist and creator of consulting firm WeatherTiger, in an email. “Mid-latitude and subtropical air masses with very low moisture content aloft repeatedly dove south and were entrained into [tropical] waves, choking off the [thunderstorm] building blocks of tropical cyclone development, despite generally favorable shear and ocean temperatures.”
Philip Klotzbach, lead hurricane researcher at Colorado State University, explained that “frequent incursions” of dry air have been resulting from a feature known as a TUTT, or a tropical upper-tropospheric trough. That’s a broad regime of lower air pressure, cooler/drier air and spin.
“The TUTT is typically associated with increased westerly shear as well as dry air being brought southward from the mid-latitudes,” he explained.
He ascribed the doldrums of July and early August to something else though — wind shear, or a change of wind speed and/or direction with height. A surplus of shear is usually detrimental fortropical systems, since it knocks them off-kilter before they can vertically develop.
The atmosphere is like a symphony orchestra, with overtones, undertones, harmony and dissonance — all of which combine into a final product that we experience as the weather. But much like that symphony, individual instruments play a role. Even if 95 percent of the instruments are playing at the correct pitch and volume, an aggressive and imaginative tuba player can ruin the performance. This season has had its fair share of tubas.
Klotzbach cited the TUTT as one of the main wild cards in a less-than-perfect forecast. He explainedin his email to The Washington Postthat the signal preceding the formation of a TUTT is usually found at the mid-latitudes, “and there’s just not that much predictability there.”
“We’ll have to do more research into potential predictability of the TUTT,” he wrote.
It’s also possible that the “triple dip La Niña” ongoing currently threw off weather models. That means we’re on the third consecutive year with a pulse of La Niña; that’s only happened in two other stretches since 1950. Since there’s not much precedent, it’s possible there’s something forecasters may be missing. We just don’t know what.
What’s in store for the rest of the season?
While it’s certainly looking like early-season predictions won’t pan out entirely, some are reluctant to put the nail in the coffin yet — and for good reason.
“I hesitate at this point to say that the seasonal forecast is going to be a complete bust,” wrote Klotzbach. “Now if we’re sitting at 6 named storms, 2 hurricanes and 0 major hurricanes at the end of September, we’d be talking massive bust potential. But it’s certainly not out of the realm of possibility to get 6-8 hurricanes from this point onward in the season.”
He pointed to the “oddball” season of 2001, during which no hurricanes formed until Sept. 9, followed by a flurry of nine of them — two more than average.
For the next two weeks, he is predicting a 70 percent chance of near-normal activity, 25 percent chance of above-normal activity and 5 percent chance of below-normal activity.
“Odds of a near-normal season (75-125 ACE) have nearly tripled to 55% as the chances of a hyperactive year have shrunk from 45% to less than 5% over that time,” wrote Truchelut in an email. “It is fairly safe to say at this point that deterministic calls for hyperactivity (165+ ACE) are likely to bust.”
At present, there are three systems to watch in the Atlantic. One near the Lesser Antilles has been on the verge of development for days, though dry air feeding into it has been holding it back. That said, models are split on just how intense it will get. Odds are it will become a named tropical storm or even hurricane north of the Leeward Islands in the coming days before recurving out to sea this weekend.
There’s also a system with moderate odds of development in the vicinity of Cabo Verde in the far eastern Atlantic, but that too should remain over the open ocean.
Perhaps the most interesting disturbance at this point is a swirl of thunderstorms wrapped up within a broader low pressure system over the north central Atlantic. It was named Tropical Storm Danielle on Thursday morning, ending the drought in named storms, and is forecast to become a hurricane in the days ahead over the open Atlantic. It is not a threat to land.
For now it’s important to remember that, regardless of how a season stacks up as a whole, it only takes one storm to turn a quiet season into a devastating one. In 1992, the first storm didn’t form until late August, and the overall season only featured seven storms. But the first of them was Andrew, the Category 5 that ravaged South Florida.