A tropical storm strengthened into a powerful typhoon in less than 12 hours, forcing the state weather forecasting agency to raise storm signal warning to its highest for the day on areas in Visayas and Mindanao led by prime tourist spot Siargao, Samar, Leyte.

As of 8 pm Monday, Typhoon ''Tino'' was located 95 km southeast of Guiuan, Eastern Samar. It had winds of up to 140 kilometers per hour and gusts of up to 170 kilometers per hour.

The dark skies over Metro Manila is caused by the shear line, said the Philippine Atmospheric, Geophysical, Astronomical and Astronomical Services Administration (Pagasa).

It slowed down from 30 kilometers per hour to 20 kilometers per hour as it heads west. It is expected to make landfall or pass very close to HomonhonI Islands or Dinagat Islands Monday night, instead of Guiuan, the Pagasa 8 pm bulletin said.

Pagasa forecasts a second landfall over Leyte or Southern Leyte early Tuesday morning before crossing Visayas and northern Palawan until early Wednesday.

''Heavy rainfall, severe winds, and storm surge may still be experienced in localities outside the landfall point and the forecast confidence cone,'' Pagasa said.

Tropical Cyclone Warning Signal No.4 was raised over the extreme southeastern portion of Eastern Samar (Guiuan), the southern portion of Leyte (Mahaplag, Abuyog, City of Baybay, Inopacan, Hilongos, Hindang, Bato, Matalom, Javier), Southern Leyte, Camotes Islands, and the northeastern portion of Bohol (Pres. Carlos P. Garcia, Getafe, Trinidad, Ubay, Bien Unido, Talibon).

Tropical Cyclone Warning Signal No.3 is up over the southern portion of Eastern Samar (Mercedes, Lawaan, Balangiga, Giporlos, Quinapondan, Salcedo), the southern portion of Samar (Marabut), the central portion of Leyte (Tanauan, Palo, Tabontabon, Isabel, Merida, Palompon, Ormoc City, Dagami, Pastrana, Burauen, Albuera, Macarthur, La Paz, Mayorga, Dulag, Julita, Tolosa, Matag-Ob, Villaba, Kananga, Jaro), the northern and central portions of Cebu (Borbon, Sogod, Catmon, Carmen, Danao City, Compostela, Liloan, Lapu-Lapu City, Cordova, Consolacion, Mandaue City, Cebu City, Asturias, Balamban, Tuburan, Tabuelan, Tabogon, City of Talisay, City of Bogo, San Remigio, Medellin, Daanbantayan, Sibonga, City of Carcar, San Fernando, City of Naga, Minglanilla, Toledo City, Aloguinsan, Pinamungahan, Barili, Dumanjug) including Bantayan Islands, and the central and eastern portions of Bohol (San Miguel, Mabini, Buenavista, Inabanga, Danao, Dagohoy, Guindulman, Pilar, Alicia, Candijay, Anda, Jagna, Duero, Sierra Bullones, Carmen, Sagbayan, Clarin, Tubigon), the northern portion of Negros Oriental (Vallehermoso, Canlaon City, City of Guihulngan), the northern portion of Negros Occidental (Hinigaran, Moises Padilla, Isabela, La Castellana, Pontevedra, San Enrique, La Carlota City, Cadiz City, Bago City, Enrique B. Magalona, Toboso, Valladolid, Salvador Benedicto, Sagay City, Bacolod City, Murcia, City of Escalante, Calatrava, San Carlos City, Silay City, Pulupandan, City of Victorias, City of Talisay, Manapla), Guimaras, and the eastern portion of Iloilo (Concepcion, Barotac Nuevo, Ajuy, Iloilo City, Anilao, Barotac Viejo, Leganes, Zarraga, Dumangas, Banate) and the rest of Surigao del Norte. DMS