MANILA, Philippines?(UPDATE) Tropical depression "Maring" has maintained its strength as it continues to move northward, the Philippine Atmospheric, Geophysical, and Astronomical Services Administration said Wednesday.

Meanwhile, another low pressure area was seen 690 kms east of Casiguran, Aurora, Pagasa said.

In its latest weather bulletin, Pagasa said that Maring was seen 130 kilometers west of Vigan City or 150 kms west northwest of Baguio City.

The weather disturbance has maintained its strength of 55 kph near the center and is moving northward "slowly," the state-run weather bureau said.

Storm warning signal number 1 remain raised over the provinces of Ilocos Norte, Ilocos Sur, La Union, Abra, Pangasinan, and Zambales, Pagasa said.

Maring is expected to enhance the southwest monsoon bringing occasional rains over Luzon, Pagasa said.

"Residents in low-lying areas and near mountain slopes are advised to take all necessary precautionary measures against possible flashfloods and landslides," Pagasa warned.

Maring is forecast to be 90 kms west northwest of Laoag City by Thursday morning, at 250 kms northwest of Laoag City by Friday morning, and 480 kms northwest of Laoag City by Saturday morning, Pagasa said.