Based on the Severe Weather Bulletin #12 issued at 08:00 AM today by the Philippine Atmospheric Geophysical and Astronomical Services Administration (PAGASA), Severe Tropical Storm “ULYSSES” is expected to intensify into a typhoon in the next 12 to 24 hours affecting Metro Manila and portions of CALABARZON and Central Luzon. Heavy to intense rainfall can be expected on these areas which could generate volcanic sediment flows or lahars, muddy streamflows or muddy run-off in rivers and drainage areas on Pinatubo and Taal volcanoes. DOST-PHIVOLCS thus strongly recommends increased vigilance and readiness of communities in pre-determined zones of lahar and related hazards on these volcanoes.

 

Prolonged and intense rainfall may generate non-eruption lahars on major rivers draining western Pinatubo Volcano where significant deposits of the 1991 PDCs remain on the watershed. Pinatubo lahars are likely be channel-confined and occur on the upper to middle reaches of the Sto. Tomas- Marella and Bucao River systems but may transition to muddy streamflows and floods on the lower reaches and affect adjacent communities of San Marcelino, San Narciso, San Felipe and Botolan, Zambales Province. Muddy streamflows may likewise be generated along the O’Donnell and Pasig-Potrero River systems draining the Pinatubo edifice to the north and southeast, respectively and affect downstream communities in Tarlac and Pampanga Provinces.

 

Prolonged and heavy rainfall may also generate muddy streamflow and muddy runoff around Taal Volcano, particularly on the slopes west of Taal Lake where thin remnant ash can be remobilized in streams and roads and overland of the lakeward slopes. In particular, muddy streamflow and runoff can recur on previously affected communities of Agoncillo and Laurel, Batangas Province.

 

DOST-PHIVOLCS strongly advises the communities and local government units of the above identified areas of risk to continually monitor the storm conditions and take pre-emptive response measures for their safety from “ULYSSES.”

 

 

DOST-PHIVOLCS