Heavy rainfall from Tropical Storm Ada could spawn lahar flows from Kanlaon Volcano in Negros Island, the Philippine Institute of Volcanology and Seismology (Phivolcs) said Friday.

In an advisory issued at 11 AM, PHIVOLCS said rains from Ada could trigger "volcanic sediment flows or lahars, sediment-laden streamflows or muddy run-off and related siltation in rivers and drainage areas" around the volcano.

"Prolonged heavy rainfall could generate life-threatening lahars and sediment-laden streamflows on major channels draining the southern, western and eastern slopes of Kanlaon Volcano," said PHIVOLCS.

Kanlaon volcano is currently under Alert Level 2.

PHIVOLCS warned that lahars could originate not only from recent volcanic deposits but also from weakened slopes previously destabilized by Supertyphoon Tino in November 2025.

Post-eruption and non-eruption lahars alike could pose serious risks to nearby towns and cities, Phivolcs said.

Communities in Bago City, La Carlota City, La Castellana, Moises Padilla, San Carlos City in Negros Occidental, and Canlaon City in Negros Oriental, along rivers such as the Ibid, Cotcot, Talaptapan, Malaiba, Panubigan, Buhangin–Indurayan, Najalin, Inyawan, Maragandang, Panun-an, Intiguiwan, Camansi, Maao, Tokon-tokon, Masulog, Binalbagan, Taco, and Linothangan rivers are particularly vulnerable.

"These communities as well as those further downstream of the above channels are advised to be prepared in case evacuation becomes necessary and to avoid traversing affected streams even those farther downslope of the volcano," said Phivolcs.

"Kanlaon lahars, which were shown by Supertyphoon Tino to be strong enough to transport enormous volumes of gravel and boulders, could threaten communities by their force of impact, inundation, burial and wash out.

The bureau reiterated to local government units and residents in high-risk areas to closely monitor weather updates and take pre-emptive measures to ensure their safety.