MANILA - Typhoon "Lawin" has maintained its strength and speed as it moves towards Northern Luzon, and is expected to gain strength before making landfall, the state weather bureau said.

Almost all provinces in Northern Luzon have been placed under storm signal number 1 Tuesday afternoon as "Lawin" nears.

In its 5 p.m. weather bulletin, PAGASA said the following areas under signal number 1:

Ilocos Norte, Apayao, Calayan Group of Islands, Batanes Group of Islands, Isabela, Kalinga, Abra, Ilocos Sur, Mt. Province, Ifugao, Quirino, Nueva Vizcaya, Benguet, La Union, Aurora, Nueva Ecija, Pangasinan, Catanduanes, Polillo Islands

These areas are expected to have minimal rainfall on Wednesday, but will be battered by "moderate to intense rains" when "Lawin" makes landfall Wednesday afternoon, PAGASA said.

Storm signals 4 and 5 may be raised over Cagayan, Calayan Group of Islands, Apayao, Ilocos Norte, and Northern Isabela by Wednesday evening as these provinces are in the direct path of the typhoon, PAGASA said.

The state weather bureau also warned of storm surges measuring up to five meters high along the coasts of Cagayan, Calayan Group of Islands, Isabela and Ilocos Norte as "Lawin" continues to pack winds up to 185 kilometers per hour (kph) and gustiness up to 230 kph as it continues to move west northwest at 25kph.

"Lawin" is also expected to make landfall over Cagayan Area by Thursday early morning (Oct. 20) then will cross Apayao and Ilocos Norte. "Lawin" is expected to leave the Philippine Area of Responsibility (PAR) on Friday, said PAGASA.

The Magat dam continues its spilling operation with three water gates opened, the Binga dam opened two gates, while the Ambuklao dam opened a single gate.

Other major dams in Luzon such as the San Roque, Pantabangan, and Angat dams have yet to reach their spilling levels, officials said.