Officials at the Central Pacific Hurricane Center are urging Hawaii residents to remain vigilant as Tropical Storm Ana continues its leisurely approach toward the state.
The system was upgraded from a tropical depression to a tropical storm Monday afternoon as maximum sustained winds topped 45 mph.
As of 11 p.m. Monday the storm was about 925 miles east-southeast of Hilo, moving northwest at about 7 mph. Tropical storm-force winds extended outward up to 25 miles. The storm is expected to gather strength as it continues on its current path until at least Wednesday, according to the center.
"We expect a slow, forward movement and gradual intensification through the forecast period," said National Weather Service forecaster Tom Birchard.
"Ana could develop into a hurricane by Wednesday night."
But Birchard stressed that the current forecast period extends only to Saturday, at which point Ana is still expected to be a couple of hundred miles southeast of Hawaii island.
"It’s too early to tell," Birchard said. "The potential impacts could come next week."
Should the storm proceed in a straight path, it could hit the south side of Hawaii island, piling onto recent woes in a Puna district still recovering from Tropical Storm Iselle and bracing for the arrival of the June 27 Kilauea lava flow, which could reach Pahoa in two weeks.
Hawaii County Civil Defense Director Darryl Oliveira said county personnel will canvass the area door to door to warn residents about the storm.
"Many people in some of these areas may not be aware of what’s happening outside their own community," he said. "If we can do something to raise awareness, we can prevent anyone getting hurt or potential problems."
Oliveira warned that the storm is likely to generate high surf near Kapoho, Punaluu, Vacationland and Kings Landing.
Storm conditions could also affect Civil Defense’s ability to conduct aerial surveys of the June 27 lava flow, which was just over a half-mile from the nearest street in Pahoa after advancing about 85 yards between Sunday and Monday.
In advance of any potential tropical storm or hurricane emergency, the National Weather Service has been encouraging residents to stock up on essential items and to monitor weather forecasts for important updates.
As Birchard noted, the state has some immediate weather concerns due to an upper-level low (also called a cold-core cyclone) unrelated to the approaching tropical storm.
The massive pool of cold interacting with warm ocean conditions triggered thunderstorm activity from Hawaii island to Oahu on Monday.
The instability prompted the weather service to issue a winter weather advisory for the summit areas of Hawaii island, effective through 6 a.m. Tuesday.
The advisory warned of accumulations of up to 3 inches of snow in summit areas above 12,000 feet, with locally higher amounts due to thunderstorms.
Temperatures were expected to dip into the mid-20s in the affected areas.
The weather service also issued a flood advisory for Hawaii island due to heavy rain extending from 8 miles northeast of Kawaihae to Pepeekeo. Heavy rain was also detected from Keahole Point to Milolii and from Naalehu to Wood Valley.
The advisory expired at 4:15 p.m.
Heavy showers are expected to continue to move in a northwesterly direction across the island chain through Tuesday.
The thunderstorms have brought associated high lightning activity.
"If you are outside and you can hear thunder, you can be hit by lightning," Birchard said. "Like we always tell people here, ‘Don’t be Hawaii’s first lightning death.’"
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Freelance reporter Megan Moseley contributed to this report.
