Newly developed Tropical Depression Wilma, shear line to dump rain

MANILA, Philippines – The low pressure area inside the Philippine Area of Responsibility developed into a tropical depression at 8 am on Thursday, December 4.

It was given the local name Wilma, as the country’s 23rd tropical cyclone for 2025. It is also the first tropical cyclone for December.

In a press conference past 11 am on Thursday, the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) said Wilma was located 625 kilometers east of Catarman, Northern Samar, as of 10 am.

The tropical depression is moving west southwest at 20 kilometers per hour, with maximum sustained winds of 45 km/h and gustiness of up to 55 km/h.

PAGASA expects Wilma to make its first landfall in Eastern Visayas or Dinagat Islands between Friday evening, December 5, and Saturday morning, December 6. Then it is projected to cross the Visayas until Monday, December 8; emerge over the Sulu Sea; and move over the northern portion of Palawan between Monday evening and Tuesday morning, December 9.

The weather bureau added that Wilma could slightly intensify before hitting land, “but will likely remain a tropical depression throughout the forecast period.”

Although Wilma is likely to remain a tropical depression, it will trigger moderate to intense rain — mainly in parts of the Visayas and Mindanao — in the next three days. Floods and landslides are expected.

Thursday noon, December 4, to Friday noon, December 5

• Heavy to intense rain (100-200 millimeters): Northern Samar, Eastern Samar
• Moderate to heavy rain (50-100 mm): Samar, Biliran, Leyte, Southern Leyte, Cebu, Bohol, Negros Oriental, Negros Occidental, Surigao del Norte, Dinagat Islands, Agusan del Norte, Misamis Oriental, Camiguin

Friday noon, December 5, to Saturday noon, December 6

• Heavy to intense rain (100-200 mm): Northern Samar, Eastern Samar, Samar, Leyte, Biliran, Cebu, Negros Occidental
• Moderate to heavy rain (50-100 mm): Southern Leyte, Bohol, Negros Oriental, Siquijor, Aklan, Capiz, Iloilo, Antique, Guimaras, Surigao del Norte, Dinagat Islands, Agusan del Norte, Misamis Oriental, Misamis Occidental, Camiguin

Saturday noon, December 6, to Sunday noon, December 7

• Heavy to intense rain (100-200 mm): Romblon, Aklan, Capiz, Iloilo, Antique, Guimaras, Negros Occidental
• Moderate to heavy rain (50-100 mm): Masbate, Northern Samar, Samar, Biliran, Leyte, Cebu, Bohol, Negros Oriental, Siquijor

Wilma is also bringing strong winds. PAGASA raised Signal No. 1 for the following provinces at 11 am on Thursday, which means they have lead time of 36 hours to prepare for strong winds from the tropical depression:

• Northern Samar
• Eastern Samar
• Samar
• Biliran
• Leyte
• Southern Leyte
• Surigao del Norte including Siargao Island and Bucas Grande Island
• Dinagat Islands

In areas not under a tropical cyclone wind signal, strong to gale-force gusts are still possible due to the northeast monsoon or amihan.

Thursday, December 4

• Ilocos Region, Cordillera Administrative Region, Cagayan Valley Aurora, Bataan, Calabarzon, Occidental Mindoro, Oriental Mindoro, Romblon, Marinduque, Bicol, Visayas

Friday, December 5

• most of Luzon and Visayas

Saturday, December 6

• most of Luzon, Visayas, Zamboanga Peninsula, Misamis Occidental

In addition, Wilma and the northeast monsoon are affecting conditions in the country’s seaboards.

Up to very rough seas (travel is risky for all vessels)

• Northern and eastern seaboards of Catanduanes; seaboard of Northern Samar – waves up to 5.5 meters high
• Seaboards of Batanes, Babuyan Islands, Cagayan, Ilocos Norte, and Eastern Samar; northern seaboard of Aurora; eastern seaboards of Polillo Islands, Albay, and Sorsogon; northern and eastern seaboards of Camarines Norte and Camarines Sur – waves up to 4.5 meters high

Up to rough seas (small vessels should not venture out to sea)

• Seaboard of northern mainland Quezon; remaining seaboard of Aurora – waves up to 4 meters high
• Seaboard of Ilocos Sur; eastern seaboards of Dinagat Islands and Siargao-Bucas Grande Islands – waves up to 3.5 meters high
• Seaboards of La Union, Pangasinan, and Surigao del Sur – waves up to 3 meters high

Up to moderate to rough seas (small vessels should take precautionary measures or avoid sailing, if possible)

• Seaboard of Pangasinan; western seaboards of Bataan and Occidental Mindoro including Lubang Island; eastern seaboard of Davao Oriental – waves up to 2.5 meters high
• Seaboards of northern Palawan including Cuyo Islands, Romblon, Aklan, and Antique; northwestern seaboard of Masbate including Burias Islands; western seaboard of Marinduque; eastern seaboard of Oriental Mindoro – waves up to 2 meters high

Shear line

Aside from Wilma, the shear line, or the point where cold air from the northeast monsoon converges with the easterlies or warm winds from the Pacific Ocean, will bring significant rain as well.

These provinces in Southern Luzon are expected to be affected by the shear line:

Thursday noon, December 4, to Friday noon, December 5

• Heavy to intense rain (100-200 mm): Catanduanes, Albay, Sorsogon
• Moderate to heavy rain (50-100 mm): Masbate

Friday noon, December 5, to Saturday noon, December 6

• Heavy to intense rain (100-200 mm): Catanduanes, Albay, Sorsogon, Masbate
• Moderate to heavy rain (50-100 mm): Romblon, Camarines Norte, Camarines Sur

Saturday noon, December 6, to Sunday noon, December 7

• Moderate to heavy rain (50-100 mm): Quezon, Marinduque, Oriental Mindoro, Camarines Norte, Camarines Sur, Catanduanes, Albay, Sorsogon

Floods and landslides are likely, too.

PAGASA advised the public to monitor updates on both Wilma and the shear line. – Rappler.com