Brewing tropical storm to bring flood risk to Philippines in final days of 2018

By Kristina Pydynowski, AccuWeather senior meteorologist

By Eric Leister, AccuWeather senior meteorologist

December 27, 2018, 7:41:14 AM EST

A tropical depression is expected to spread flooding rain across the northern and central Philippines later this week and into this weekend.

The tropical depression churning toward the Philippines has been given the local name of Usman. When named by the Japanese Meteorological Agency (JMA), the official issuing agency in the western Pacific basin, it will be called Pabuk.

The JMA will designate it as Pabuk when it gains tropical storm strength, which AccuWeather meteorologists anticipate will happen before the depression reaches Samar Island.

Regardless of its exact strength, residents of the central Philippines and Luzon (mainly southern and eastern areas) are being put on alert for the risk of flooding.

Rain from the storm reached the eastern coast of the central Philippines on Thursday and central and northern parts of the country will endure further downpours through this weekend.

Usman is expected to make landfall on Samar Island early Friday afternoon before continuing on a westward track across the nation.

Usman is not forecast to depart the Philippines until Saturday night after it crosses Palawan.

"Due to the slow movement, heavy rain and flooding are the biggest threats from this storm," AccuWeather Meteorologist Tyler Roys said.

The central Philippines will endure a prolonged period of heavy rainfall with Roys expecting a widespread 75-150 mm (3-6 inches) and an AccuWeather Local StormMax™ of 300 mm (12 inches).

"Given the recent heavy rain last week and what Usman will produce, the flood threat is enhanced," he stated.

Residents from Borongan City, Cebu, Iloilo and Legazpi should remain vigilant for flash flooding in the upcoming days. Low-lying, urban and other poor drainage areas will be most susceptible to flooding.

Rivers and streams can overflow their banks and inundate neighboring land and communities. There is also a risk of mudslides in the higher terrain.

Remember never to drive through flooded roads to avoid a potentially deadly situation. Air travel can have some cancellations or delays.

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"While the storm is expected to track through the central Philippines, there will also be heavy rainfall and the risk of flooding and mudslides along the eastern coast of Luzon," according to AccuWeather Senior Meteorologist Dave Houk.

These areas can also expect 75-150 mm (3-6 inches) of rain and an AccuWeather Local StormMax™ of 300 mm (12 inches).

"As tropical moisture surges northward, a wind-swept rain will get wrung out over these communities this weekend," he said.

While the storm is not expected to rapidly strengthen, it can become strong enough to cause minor wind damage and sporadic power outages.

Manila can face a period of these strong winds, along with rain heavy enough to cause localized flooding and travel disruptions on Friday night into Saturday night.

After impacting the Philippines, Usman will move into the South China Sea to close out 2018. A brief period of strengthening is expected as the storm remains over the open water Sunday into early Monday.

"Conditions should become less conducive and cause Usman to weaken as it approaches Vietnam Monday night and Tuesday," according to Roys.

A turn toward the southwest will take the storm just south of southern Vietnam during the middle of next week and a direct hit is not forecast at this time.

Heavy rain may still spread into central and southern Vietnam at the start of the new year, raising the risk for flash flooding and mudslides.

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