MANILA, Philippines ? Parts of Northern Luzon were placed under signal number 1 after the low pressure area east off Luzon intensified into a tropical depression, an official from the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa) said Monday.

In a telephone interview, Pagasa weather Chief Nathaniel Cruz said that the tropical depression, codenamed ?Tino?, is the 20th tropical cyclone that has entered the Philippine area of responsibility for the year and the first for the month of November.

This latest weather disturbance was reported a day after tropical storm ?Santi? (international name: Mirinae) exited the country.

In its latest weather bulletin, Pagasa said Tino was seen 270 kilometers east of Tuguegarao City packing maximum sustained winds of 55 kilometers per hour near the center.

The weather disturbance is forecast to move west northwestward at 15 kilometers per hour.

Storm Signal warning number 1 has been raised over Isabela, Cagayan, Babuyan Island, Calayan Islands and the Batanes Group of Islands, Pagasa said.

Residents in low-lying areas and near mountain slopes in areas under signal number 1 were advised to take all the necessary precautionary measures against possible flashfloods and landslides, the state-run weather bureau said.

Meanwhile, the rest of Northern Luzon will experience occasional rains and gusty winds caused by the Northeast monsoon.

Cruz added that the tropical depression is not expected to intensify due to the northeast monsoon which is a ?cooler and relatively dry air mass.?

?It does not promote further intensification of tropical depression Tino. However, the northeast monsoon will bring strong winds and rough seas especially to the eastern seaboards of northern Luzon,? Cruz said.

By Tuesday afternoon, Tino is forecast to be at 90 kilometers north of Aparri, Cagayan or over the Vicinity of Calayan island.

Tropical depression Tino is expected to be at 420 kilometers northwest of Aparri, Cagayan or 330 kilometers west northwest of Basco, Batanes by Wednesday afternoon, Pagasa said.