May 9, 2006— Some early signs are beginning to roll in suggesting the 2006 hurricane season will not be the record that 2005 was, say climate researchers.
The latest hopeful sign is the recent demise of the hurricane-boosting La Niña condition in the Pacific. After that is the storm-fueling sea surface temperature in the Atlantic, which is not so hot this year.
Satellite sensors and ocean buoys show that the La Niña condition — the vast pooling of unusually cool surface water in the eastern equatorial Pacific Ocean — which formed late last year is now almost entirely gone. And while that does not guarantee a hurricane-free year, it's a good sign that the worst possible hurricane-making scenarios are not in the offing.
"That still is good news," said oceanographer David Adamec of NASA's Goddard Space Flight Center in Maryland.
The 2005 hurricane season smashed all previous records, according to NOAA. The year saw 28 named storms (previous record: 21 in 1933); 15 hurricanes (previous record: 12 in 1969); four major hurricanes hitting the United States (previous record: three in 2004); and four Category 5 hurricanes (previous record: two in 1960 and 1961).
La Niña helps hurricanes by pushing the jet stream northward and away from the hurricane factory in the tropical Atlantic. The jet stream tends to kill nascent hurricanes by shearing off the heads of tall thunderclouds.
It's La Niña's brother — the infamous warm water El Niño condition in the eastern equatorial Pacific — that tends to pull the jet stream south so it can chop the heads of successive wannabe Atlantic hurricanes. Right now, however, neither condition reigns, making the Pacific "normal" said Adamec.
"It's so normal out there (in the Pacific Ocean), it's incredible," said Adamec of the sea surface and subsurface temperatures compared to years past.
But there's a downside to normal: It's a lot less revealing about what sort of weather to expect a few months down the line. It's a condition that Bill Patzert of NASA's Jet Propulsion Laboratory in California likes to call the "La Nada" condition, borrowing the Spanish word for "nothing."
"You have got to be careful with La Nada," said Patzert, who is an oceanographer. "El Niña and La Niña both give structure to the jet stream. Without structure, you get misbehavior."
Normal conditions force scientists to look even more closely at other factors, like how hot the water is getting right where hurricanes form, explained Adamec.
"The Atlantic is a little bit warm," Adamec told Discovery News. But it's nothing like last year, which was the worst hurricane season in history. "Last year the water was really warm. It was downright toasty."
How much warmer the water gets depends a lot on how long a persistent subtropical high pressure system remains parked over the Atlantic, said Adamec. The high pressure keeps the skies clear and lets the sun beat down and heat up the waters.
"Remember, this is the first week in May," said Patzert. The hurricane season officially begins June 1. "So you definitely want to stay tuned."
