The Joint Typhoon Warning Center upgraded Invest 99W to a medium chance for development overnight and may issue a tropical cyclone formation alert in the coming days, National Weather Service Guam Warning Coordination Meteorologist Landon Aydlett said on Good Morning Marianas Wednesday, a shift from Tuesday’s weekly outlook, which had rated the disturbance “sub low.”
Aydlett said forecast models and the general steering pattern move 99W generally northward toward Wake Island as it goes into the North Pacific. “Not every disturbance, not every tropical cyclone has its eye set on the CNMI,” he said, urging the public to read full advisories rather than react to map symbols. “These things go in different directions.”
The JTWC has also opened a second area of investigation, Invest 90W, on a weak circulation closer to the Marianas along the monsoon trough that stretches from former Typhoon Saudel’s wake through both systems. Aydlett said 90W actually looks better organized at the surface than 99W but its future is inconclusive and it may meander, while models favor 99W for development. A third disturbance may emerge in the Philippine Sea to the west; nothing developing there looks like a problem for the region, he said.
The immediate weather Wednesday morning was on Guam, where a flood advisory was upgraded to a flash flood warning for the southern half of the island at about 7 a.m., running through 8:30 a.m., as heavy showers trained over the area. Aydlett flagged Cross Island Road and the Leo Palace area as concerns, with runoff flushing through central Guam’s rivers toward Pago, Talofofo and Ylig bays. Rota saw lighter showers, and Saipan and Tinian largely stayed dry through the morning.
The trough will keep winds light and variable across the CNMI for a couple of days, making afternoon island convection possible, with the wet monsoonal pattern of scattered to locally heavy showers holding through the end of the week. “This is as wet season as it gets,” Aydlett said.
Aydlett, just back from a work trip through Chuuk and Pohnpei, said Typhoon Saudel’s approach had him ready to fly back early. “That was too close for comfort,” he said, noting the office’s preseason outlook anticipated a busy year, and the region should expect a number of tropical systems in the coming weeks.
