The two main ingredients prompting forecasts for a busy season are extremely warm sea surface temperatures and a pending La Niña climate pattern.
Kimberly MillerPalm Beach Post
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Colorado State University reduced the number of named storms it is predicting this hurricane season following a weekslong lull between Tropical Storm Chris and Hurricane Debby.
The revised forecast, which is still calling for a hyperactive season, was released Tuesday as part of CSU's regularly scheduled updates.
The seasonal forecast now calls for a total of 23 named storms, down from a July forecast of 25, including 12 hurricanes. Of the 12 hurricanes, six are forecast to be major storms of Category 3 strength or higher. The numbers include tropical storms Alberto and Chris and Hurricane Beryl.
An average hurricane season has 14 named storms, seven hurricanes and three major hurricanes.
The National Oceanic and Atmospheric Administration's Climate Prediction Center will release its updated August forecast for this hurricane season on Thursday, Aug. 8.
CSU senior researcher and hurricane expert Phil Klotzbach said the dip to 23 named storms isn't a significant change. The initial forecast issued in April also called for 23 named storms. CSU has issued August updates to its forecasts since 1984.
"Basically, we just didn't have any new named storms form between Chris and Debby, so the odds of getting 21 additional named storms are pretty low," said Klotzbach, who is the lead writer of the CSU forecast. "The other numbers including ACE (Accumulated Cyclone Energy) stayed the same as our July forecast."
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Accumulated Cyclone Energy is the measure of a hurricane's strength and longevity. For the season, which runs through Nov. 30, CSU is forecasting an ACE of 230, which is nearly double an average year.
Also, the forecast for 12 hurricanes is tied with 2020 for the most hurricanes ever forecast for an August CSU update.
"July is often kind of a dud," said Chris Davis, senior scientist at the National Science Foundation National Center for Atmospheric Research. "It's amazing some years how fast the basin wakes up. You go from wondering when the next one is going to happen to having three on the map at the same time."
CSU also began its two-week forecasts on Tuesday and is calling for an 85% chance of above-normal activity through August 19.
Atmospheric conditions continue to give forecasters high confidence that despite a break between the June 30 landfall of Tropical Storm Chris and Monday's landfall of Category 1 Debby, the remainder of the season will by active. Years with similar conditions include 2005 and 2020, according to CSU.
There were 28 named storms in 2005 — a record breaker until 2020 when 30 storms formed. The 2005 hurricane season also stretched deep into winter and even jumped into 2006 with Tropical Storm Zeta finally calling it quits Jan. 6. The 2020 season's last named storm was Hurricane Iota, which lasted through Nov. 18.
University of Miami Senior Research Associate Brian McNoldy noted that Hurricane Debby was premature compared to an average hurricane season.
"Climatologically, the fourth named storm forms on August 15, and the second hurricane forms on August 26," McNoldy wrote in his Tropical Atlantic Update blog before Debby formed. "So if Invest 97L does become Tropical Storm Debby or Hurricane Debby, it will be well ahead of the normal pace."
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The two main ingredients prompting forecasts for a busy season are extremely warm sea surface temperatures and a pending LaNiñaclimate pattern. LaNiña, which has a 70% chance of rising this month through October, occurs when the waters in the tropical Pacific Ocean cool. The ripple effect through the atmosphere reduces the wind shear in the Atlantic, giving budding storms room to grow.
CSU said in its August forecast that wind shear during June and July was well below normal, which typically correlates with continued below-normal wind shear through the peak of the season.
"La Niña is not a switch. It's an evolution of the ocean," Davis said. "Many years we don't get any hurricanes until well into August so by that measure the season is already active."
As of Tuesday morning, the National Hurricane Center was giving a tropical wave east of the Windward Islands a 30% chance of formation over the next seven days. The area of potential development is south of Cuba and closer to the Yucatan Peninsula.
McNoldy said he does not think the wave is a threat to Florida.
Kimberly Miller is a journalist for The Palm Beach Post, part of the USA Today Network of Florida. She coversreal estate and how growth affects South Florida's environment. Subscribe to The Dirt for a weekly real estate roundup. If you have news tips, please send them to kmiller@pbpost.com.Help support our local journalism; subscribe today.
