An El Niño watch issued last month will continue after the latest forecast for the global climate pattern increased its chances of appearing this fall or winter.
The Climate Prediction Center is now forecasting a 65 percent chance El Niño conditions will be in place by the fall, and up to a 70 percent chance by winter.
That’s up from a June forecast that predicted a 50 percent chance of a fall arrival, and 65 percent chance of a winter arrival.
For Florida, the periodic warming of the equatorial Pacific Ocean can mean a less active hurricane season with fewer powerhouse Cat 5 tropical cyclones.
But it also leans toward stormier days during the darkest part of the year when the Sunshine State typically enjoys its dry season.
“The issue for the hurricanes is does El Niño develop in time and with sufficient strength to suppress the later part of the season,” said Gerry Bell, the lead seasonal hurricane forecaster for the National Oceanic and Atmospheric Administration, in a June interview. “Conditions are evolving more toward an El Niño right now, but there is still a long way to go.”
Hurricane researchers are considering El Niño in their updated forecasts.
NOAA’s May 24 hurricane forecast for this season called for between 10 and 16 named storms, five to nine hurricanes and up to four major hurricanes of Category 3 or higher.
An average hurricane season has 12 named storms, six hurricanes and two major hurricanes.
Bell said the low end of the NOAA forecast reflects the idea that El Niño was a possibility but that the clues weren’t strong enough in May to base the prediction on it.
Colorado State University reduced its July 1 forecast to 11 named storms, four hurricanes and one major hurricane of Category 3 or higher.
The team’s start-of-season forecast on May 31 had called for 14, six and two, respectively. The historical average is 12, 6 1/2, and two. The 2017 season saw 17, 10 and 6.
Phil Klotzbach, CSU hurricane researcher and lead writer of the forecast, said an unusually cool tropical Atlantic, paired with the possibility of a weak El Niño led to the reduced forecast.
“A colder than normal tropical Atlantic provides less fuel for developing tropical cyclones but also tends to be associated with higher pressure and a more stable atmosphere,” CSU’s July 1 forecast notes. “These conditions tend to suppress Atlantic hurricane activity.”
The onset of El Niño occurs in tandem with the relaxation of the trade winds – those Earth-skimming easterlies that have guided sailing ships across the world’s oceans for centuries.
With the trade winds reduced, warm water that has piled up in the western Pacific Ocean and around Indonesia rushes back toward the east. That movement of warm water shifts rainfall patterns and the formation of deep tropical thunderstorms. The exploding storms whose cloud tops can touch the jet stream disrupt upper air patterns so winds come more out of the west.
The west winds create shear in the Atlantic, which can be deadly to budding hurricanes.
Still, with three named storms, including two hurricanes – Beryl and Chris – already come and gone, this season is coming out of the gate strong.
On average, there are only 1.3 named storms through July 17 and no hurricanes, according to CSU.
Also, accumulated cyclone energy this season stands at 14.4 when the average for this time of year is 5.1. Accumulated cyclone energy, or ACE, is a way to measure the strength and longevity of tropical cyclones.
“So in terms of ACE, we are at 326% of normal activity for the date,” said University of Miami senior research associate Brian McNoldy in a column last week. “Another way to frame it is that the ACE is currently what it climatologically would be on August 14. And as I mentioned yesterday, the last time we had two hurricanes so early in the season was 2005.”