August is about to end without an Atlantic hurricane for the first time since 2002, calling into question predictions of a more active storm season than normal.
Six tropical systems have formed in the Atlantic since the season began June 1 and none of them has grown to hurricane strength with winds of at least 74 miles (120 kilometers) per hour. Accumulated cyclone energy in the Atlantic, a measure of tropical power, is about 30 percent of where it normally would be, said Phil Klotzbach, lead author of Colorado State University’s seasonal hurricane forecasts.
“At this point, I doubt that a super-active hurricane season will happen,” Klotzbach said in an e-mail yesterday.
The most active part of the Atlantic season runs from Aug. 20 to about the first week of October. The statistical peak occurs on Sept. 10, according to the National Hurricane Center in Miami. Two storms formed in August and the hurricane center is tracking two areas of thunderstorms that have low to medium chances of becoming tropical systems within five days
Atlantic storms are watched closely because they disrupt energy operations in and around the Gulf of Mexico and cause widespread destruction when they come ashore.
In the basin now, warm sea water and a decreasing amount of wind shear that can tear at the structure of budding storms mean conditions are ripe “for a burst of activity,” said Todd Crawford, chief meteorologist at Weather Services International in Andover, Massachusetts.
“The very inactive season so far has been a bit of a head-scratcher,” Crawford said in an e-mail interview.
Air temperatures from the Caribbean to Africa have been warmer than normal this year, reducing the instability in the atmosphere that drives storm development, he said. In addition, dry air is being pulled off Africa into the Atlantic, which also cuts storm activity, he said.
Seasonal predictions were for an above-normal season. The 30-year average is for 12 storms with winds of at least 39 miles per hour, the threshold at which they are named. Nineteen such systems formed in each of the last three years.
Colorado State, which pioneered seasonal forecasts, retreated slightly on its outlook in an early August update, calling for 18 named storms. Eight should be hurricanes and three of them major hurricanes, a reduction of one at each level, the researchers said.
The National Oceanic & Atmospheric Administration also kept its call for an above-average season in an Aug. 8 outlook for 13 to 19 named storms, six to nine hurricanes and three to five major systems.
“If you don’t get your first hurricane by or before August, it’s extremely difficult to get those high storm counts, especially for hurricanes and major hurricanes,” said Matt Rogers, president of Commodity Weather Group LLC in Bethesda, Maryland. “Amazing we’re on the 90th day of the hurricane season and no hurricanes yet.”