Tropical Storm Guillermo continues to strengthen in the Eastern Pacific and maintain its course toward Hawaii. The cyclone is expected to build into a Category 1 hurricane today and maintain hurricane strength for several days before weakening back to a tropical storm on Tuesday.
But forecasters acknowledge the system has a lot of unknowns at this point. It could pass north of the state, bringing humidity reminiscent of tropical storms Ela and Enrique. It could hold its northwest track toward the island, or even weaken and veer south, said John Bravender, a forecaster with the National Weather Service in Honolulu. The storm could also intensify beyond current projections.
“We don’t want people to focus on one particular solution,” Bravender said. “It has the potential to approach the state, and people should stay up to date and prepare.”
By Tuesday night, the system is expected to be about 500 miles east of the Big Island as a tropical storm circulating 65 mph winds. At that point, a forecast break in a high pressure ridge should have the system veering onto a more northwesterly tack away from the islands, National Weather Service forecasters in Florida say.
Located 1,955 miles east-southeast of Kailua-Kona, Guillermo is set to peak with 90 mph winds on Saturday and Sunday, with some weakening beginning Monday as the system moves into an area of increased wind shear and lower sea surface temperatures. The storm is traveling west-northwest at 13 mph, with tropical storm force winds extending 60 miles from the center.
Guillermo is traveling south of a subtropical ridge, and weather models show a break in the ridge developing in the next few days, allowing the storm to begin a slight northwestward turn about 800 miles east-southeast of Hilo on Sunday. The forecast track has the storm gradually slowing in forward speed in the beginning of the week.
Dennis Feltgen, spokesman for the National Hurricane Center in Florida, cautioned that extended forecasts have a high degree of uncertainty.
“The track does appear to slow down on Monday and Tuesday, but we’ll have to see how that shakes out,” he said. “The message for Hawaii is there is no immediate cause for concern, but when a tropical cyclone is in that area, you don’t want to get caught off guard, and everyone should have a hurricane plan.”
Packing 45 mph winds, Guillermo is in a moist, unstable environment with 84 degree water conducive for development over the next several days. Forecasters with the NHC say the storm could go through a period of rapid intensification today. Satellite imagery shows bands of thunderstorms churning in the storm’s northern quadrant and entering the center from the west.
Guillermo is expected to enter the Central North Pacific basin on Saturday.
Tropical Depression Eight E became a remnant low overnight about 1,000 miles east of Hilo. The low was generating scattered thunderstorms at it moved west as 10 to 15 mph. The system is not expected to redevelop or have much effect on Hawaii.