Hurricane Gonzalo grew into a major storm that threatens Bermuda later this week, while half a world away Tropical Storm Ana may become the second system this year to sweep Hawaii’s Big Island.

Gonzalo, with top winds of 115 miles (185 kilometers) per hour, was about 770 miles south of Bermuda as of 5 p.m. East Coast time. It is a Category 3 system on the five-step Saffir- Simpson scale and may reach Category 4 strength tomorrow, the U.S. National Hurricane Center said.

“I think it has a good shot at Category 4,” said Jeff Masters, co-founder of Weather Underground in Ann Arbor, Michigan. “It would be the first in the Atlantic since 2011. I don’t think there is anything out there to slow it down.”

Gonzalo is following a path similar to Tropical Storm Fay, which swept across Bermuda earlier this week, clogging roads with debris and knocking out power to about 27,000 homes. If Gonzalo maintains its power as it moves north, it will be capable of inflicting much greater damage.

“Hurricane Gonzalo has been upgraded to a threat to Bermuda,” the Bermuda Weather Service in a statement. “Conditions will begin to deteriorate overnight Thursday and preparations should be made in advance of these increasing winds.”

Seas may reach as high as 30 feet and winds as strong as 74 mph by Oct. 17, the weather service said.

Canada Track

Environment Canada is also tracking Gonzalo’s northerly track because it has the potential to hit Newfoundland early next week.

Masters said there is a chance that Gonzalo could miss Bermuda.

“It’s a small target in a big ocean,” Masters said.

The average track error four days in advance is about 200 miles, or a little less than the distance between New York and Boston.

While the U.S. East Coast will be spared a strike from Gonzalo, surf may pound the shoreline, especially if it reaches Category 4 strength, Masters said.

In the Pacific, about 820 miles east-southeast of Hilo, Hawaii, Tropical Storm Ana is churning toward the Big Island of Hawaii. Its winds strengthened to 65 mph, up from 50 mph earlier today, the Central Pacific Hurricane Center said.

The current forecast has the storm growing to hurricane strength as it bears down on the Big Island over the weekend. Masters said the same rate of error for Gonzalo applies, so there is a chance it may miss.

In the Eastern Pacific, the hurricane center is also tracking an area of low pressure off Guatemala’s coast that has a 60 percent chance of becoming a tropical system in the next five days.
To contact the reporter on this story: Brian K. Sullivan in Boston at bsullivan10@bloomberg.net To contact the editors responsible for this story: David Marino at dmarino4@bloomberg.net Charlotte Porter, Bill Banker