The low-pressure area (LPA) east of the country has intensified into a tropical cyclone and was locally named "Gener" (international name: Saola) on Saturday.
The Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA) upgraded the weather disturbance into a tropical depression on Saturday morning but it rapidly intensified into a tropical storm in the afternoon.
Signal No. 1 has been raised over Isabela, Cagayan, Calayan and Babuyan Group of Islands, and Batanes Group of Islands.
As of 5 p.m. Saturday, "Gener" was located at 250 kilometers northeast of Virac, Catanduanes, or 450 km east-southeast of Casiguran, Aurora.
It has maximum sustained winds of 65 kilometers per hour and gustiness of up to 80 kph.
"Gener" continues to move north-northwest at 15 kph.
The tropical cyclone is not expected to make landfall but PAGASA warned that the weather disturbance will enhance the southwest monsoon or "hanging habagat" and will still bring rains over Southern Luzon, Visayas, and Mindanao, particularly over the western section.
PAGASA warned fishing boats and other small seacraft not to venture out into the seaboards of Southern Luzon, Visayas, and Mindanao due to the combined effects of "Gener" and the southwest monsooon.
Likewise, residents in the low-lying and mountainous areas in Southern Luzon, Visayas, and Mindanao were warned against possible flash floods and landslides.
Tropical storm "Gener" is expected to be at 290 kms northeast of Casiguran, Aurora, by Sunday afternoon and at 130 kms northeast of Basco, Batanes, by Monday afternoon.