Tropical Storm Calvin on Monday was slowly weakening as it headed toward the Big Island, but it was moving rapidly to the west at 22 mph and was expected to hit the island tonight or Wednesday morning.
The National Weather Service posted a tropical storm warning for Hawaii County as of 5 p.m. Monday.
“Right now, we’re looking at heavy rainfall, potentially, for the Big Island,” said Eric Lau, a forecaster for the National Service in Honolulu. “We’re looking at 4 to 8 inches. So, impacts from that could result in flash flooding and the ponding of water in low-lying areas, potentially mudslides, as well.”
Forecasts say 10 inches of rain are possible mainly in the windward Big Island.
“You know, the one beneficial thing right now is that the system is moving fast, so it’s not going to sit over one area for a very, very long time,” Lau said. “We could see a six- to 12-hour window of heavy rainfall, and then Calvin will be exiting the area quickly and moving on to the rest of the island chain.”
To those who remember Hurricane Lane in 2018, that piece of information is a silver lining.
In late August that year, Lane, a former tropical cyclone, had already passed the Big Island and was being torn to remnants by wind shear when the storm’s outer rain bands dropped a deluge of historic proportions on East Hawaii.
Mountain View received 51.5 inches of rain in a four-day period. Damage to county facilities totaled about $20 million, and an estimated 152 homes were damaged, with 59 sustaining major damage from Lane.
Gov. Josh Green on Monday said he was “pretty confident that the storm is weakening sufficiently, that it won’t do much damage, but we’ll be ready.”
“The thing that we would really have to really worry about is if we ever have a direct hit on (Honolulu Harbor),” Green said.
Calvin, as of late Monday, was packing maximum sustained winds of 45 mph with locally higher gusts, but those should lessen a bit by the time the storm reaches the island.
“What we have is 30 to 40 mph with gusts to 60,” Lau said.
County Civil Defense Administrator Talmadge Magno said it’s unlikely Calvin will inflict the type of damage done by Lane or by Tropical Storm Iselle, which downed trees and power lines in 2014, mostly in Puna, and did at least $148 million in damage.
“I kind of draw similarities to last December’s Kona Low that came through. That brought high winds and flooding rains,” Magno said. “There wasn’t really warning-level big surf with that. What we saw with that was a lot of trees came down. There was a lot of blocked access on public roads and private roads. It took out a number of utilities.
“The flooding caused road closures and damaged some of the infrastructure in Ka‘u.”
Calvin also is expected to generate high surf, perhaps life-threatening surf, along the east-facing shores of the main Hawaiian Islands over the next couple of days.
At some of the big-box stores on Monday, shoppers were making their preparations.
“We’ve had a steady flow of customers today — people getting plywood, lumber, generators, batteries — getting prepared for the storm,” said a clerk at The Home Depot in Hilo.
A manager in the consumables department at Target in Hilo said they were selling food at a brisk pace, with stronger-than-normal sales of bottled water.
Mayor Mitch Roth said camping permits islandwide for today and Wednesday are cancelled, and only residents and farmers will be allowed to travel on Waipio Valley Access Road. In addition, two emergency shelters were being readied in Ka‘u at the Robert Herkes Gymnasium in Pahala and the Naalehu Community Center.
Roth urged all residents and visitors to take this storm seriously and to make the necessary preparations for potential impacts.
“While we hope for the best, it’s crucial that we plan for the worst,” he said in a statement. “The safety of our community is our top priority, and we are taking all necessary measures to ensure that everyone remains safe and well-prepared throughout the duration of the storm.”
Authorities all noted this is the first named storm in the Central Pacific this year, and an active hurricane season is expected because of El Nino.
“The storm season is from May until November,” Green said. “Always be ready. You should have two weeks of water, two weeks of medicine, some additional food in your household. You should also know where you’re going to go.
“The counties, on their websites, have all of the sites where you would go and be protected from the storm.”
Email John Burnett at jburnett@hawaiitribune-herald.com.
Email Grant Phillips at gphillips@hawaiitribune-herald.com.