SAIPAN — National Weather Service meteorologist-in-charge Brandon Aydlett told Good Morning Marianas Saturday morning that the latest forecast track from the Joint Typhoon Warning Center reflects a Category 4 typhoon moving through the Marianas near Guam, and urged residents across the island chain to use the remaining good weather days to complete preparations before conditions deteriorate Monday.
“The latest forecast track out of JTWC does reflect a Category 4 typhoon moving through the Marianas currently right near Guam,” Aydlett said during a live interview on GMM.
Aydlett said tropical storm-force winds of at least 39 mph are expected to arrive in the Marianas starting Monday morning to midday, reaching Guam first and then Tinian and Saipan several hours later. He cautioned that the event will be prolonged, with impacts lasting from Monday midday through Wednesday afternoon or beyond.
“Don’t be surprised. It’s going to be long going,” Aydlett said.
As of the interview, Chuuk Lagoon was already being pounded by the storm, with reports of 70 mph winds at the center, large trees coming down, shoreline erosion and flooding on the western-facing islands inside the lagoon. Aydlett said Chuuk faces another 24 to 36 hours of dangerous conditions including risk of mudslides on steep terrain.
On the track, Aydlett acknowledged remaining model variability but said the forecast cone still places a 30 to 40 percent chance of typhoon conditions for Guam, 20 to 30 percent for Rota, and a 10 to 20 percent chance for Tinian and Saipan.
“While we still have that center track right over Guam, it could still go closer to Rota or even farther north,” he said. “We’ve seen it in the past.”
Aydlett explained the NWS watch and warning process, noting that watches would be issued around the 48-hour mark before the onset of damaging tropical storm-force winds, and warnings at the 24-hour mark. He said residents should pay close attention to the shift in language from “possible” in a watch to “expected” in a warning.
“Possible means something could happen or it could veer north or south and we might be spared,” Aydlett said. “When we get closer, that certainty in the forecast increases. And then the wording is going to be ‘expected.’ Something is imminent or eventually occurring. So pay attention to that wording — it is very important.”
On rainfall, Aydlett warned that the slow movement of the storm raises the threat of significant flooding.
“With this slow motion, we could be facing some significant rainfall-related flood concerns,” he said. “Heavy rainfall rates persisting for multiple hours is going to take a toll. Saipan does have some vulnerabilities in some of the low-lying areas in the southern half of the island.”
He urged residents in substandard structures to consider sheltering with family or friends in concrete buildings before conditions deteriorate.
Aydlett said NWS has extended shifts and is preparing for the long haul.
“This is going to be an endurance race,” he said. “This is going to really stress a lot of people, especially government workers, agency heads, as they go through the decision-making down to the residential level. So be prepared for this long event.”
He also offered a reminder about information sharing on social media.
“Make sure the information you’re looking at has a date and timestamp on it and it reflects the latest information,” Aydlett said. “Social media does not do the best job in parsing old information as it can be shared and comes back at the top of your newsfeed.”
NWS Guam updates are available at weather.gov/gum. The next advisory at the time of the interview was scheduled for 11 a.m. with a forecast track update at 2 p.m.
Watch the full update on the NMI News Service Facebook page and YouTube channel.
