MANILA, Philippines (2nd UPDATE) – Tropical storm "Falcon" continued to intensify Friday morning and may be classified a severe tropical storm by the afternoon, weather bureau PAGASA said.

Department of Science and Technology (DOST) Undersecretary Graciano Yumul said Falcon has gotten bigger with a diameter of 500 kilometers. He said if things do not change, Falcon will be considered a "severe tropical storm" by the afternoon.

As of 11:00 a.m., Falcon was spotted 330 km East of Basco, Batanes, moving north northwest at 19 kph. It is packing maximum sustained winds of 85 kph near the center and gusts of up to 100 kph.

Yumul warned that stronger rains will be experienced over Central and Northern Luzon as Falcon will further strengthen the southwest monsoon.

Falcon merged with a low pressure area and poured heavy rains in Metro Manila Thursday, causing neck-deep floods in some areas.

Areas such as Taguig, Quezon City, Manila, San Juan and Marikina suffered from flooding.

In Marikina, residents living near Tumana River were told to voluntary evacuate after the water level reached at a critical level.

Local officials in Albay told nearly 15,000 families to evacuate after the Bicol River, Lake Bato, and Lake Buhi neared overflow.

Falcon is expected to be 500 km North Northeast of Basco, Batanes by Saturday morning.

Signal no. 1 is still hoisted over Calayan, Babuyan Group of Islands and Batanes Group of Islands while storm warning signals were lowered elsewhere.

Flights cancelled

As of 10:00 a.m. today, a total of 26 domestic flights have been cancelled at the Ninoy Aquino International Airport (NAIA) Terminal 3 and Manila Domestic Terminal 4 as Falcon continues to bring rains over the country.

The following flights in NAIA 3 were cancelled:

• 5J 521 MNL-Naga
• 5J 522 Naga-MNL
• 5J 513 MNL-San Jose, mindoro
• 5J 514 San Jose, Mindoro-MNL
• 5J 897 MNL-Caticlan
• 5J 898 Caticlan-MNL
• 5J 913 MNL-Caticlan
• 5J 914 caticlan-MNL
• 5J 901 MNL-Caticlan
• 5J 902 Caticlan-MNL
• 5J 899 MNL-Caticlan
• 5J 900 Caticlan-MNL
• 5J 905 MNL-Caticlan
• 5J 906 Caticlan-MNL
• 5J 917 MNL-Caticlan
• 5J 918 Caticlan-MNL
• 5J 903 MNL-Caticlan
• 5J 904 Caticlan-MNL
• 5J 911 MNL-Caticlan
• 5J 912 Caticlan-MNL
• 5J 893 MNL-Caticlan
• 5J 894 Caticlan-MNL
• 5J 891 MNL-Caticlan
• 5J 892 Caticlan-MNL

Meanwhile, the following flights in MDT 4 were cancelled:

• DG 601 MNL-Basco
• DG 602 Basco-MNL

In a statement, Philippine Airlines said that as of 2 p.m., operations remain normal with some flights experiencing delay.

Yesterday, a total of 51 domestic flights were also cancelled.

Residents in low lying and mountainous areas under signal no. 1 are alerted against possible flashfloods and landslides.