Philippines: Adverse weather forecast across central, eastern, and southern regions through at least Dec. 20 /update 1

Severe weather is forecast across parts of the central, eastern, and southern Philippines through at least Dec. 20. A low-pressure area with a likelihood of cyclonic development known in the Philippines as Tropical Depression Querubin located to the southeast of Mindanao is forecast to bring heavy rainfall and thunderstorms to eastern and southeastern regions, as well as gusty winds over Davao Oriental Province and rough seas in coastal waters of the Philippines. The Philippine Atmospheric, Geophysical, and Astronomical Administration (PAGASA) has issued a Tropical Cyclone Wind Signal No. 1 warning (the lowest level on a five-tier scale) for Davao Oriental Province Dec. 17. A stationary front known as a shear line is also expected to bring heavy rainfall and thunderstorms to Bicol Region and Quezon Province and a weather trough associated with the low-pressure system is expected to bring showers and storms across the rest of Mindanao and the Visayas islands. Heavy downpours may trigger flooding in low-lying areas and landslides on unstable slopes.

As of Dec. 17, PAGASA has issued a weather advisory for heavy rainfall over parts of the region, with heavy-to-intense rainfall totals of 10-20 cm (4-8 inches) forecast across Davao Oriental Province Dec. 17-18, Dinagat Islands, Surigao del Norte, Surigao del Sur provinces Dec. 17-20, and Eastern Samar, Northern Samar, Samar, Leyte, Southern Leyte, and Biliran provinces Dec. 18-20. Moderate-to-heavy rainfall totals of 5-10 cm (2-4 inches) are forecast across other parts of the central and southern Philippines Dec. 17-20.

PAGASA has issued the following flood advisories across the country Dec. 16:

• Severe general flood advisories (the second lowest level on a four-tier scale): Across Bicol, Caraga, and Eastern Visayas and most of Davao regions.

• Moderate general flood advisories: Lanao del Sur, Maguindanao, and North Cotabato provinces in Bangsamoro Region; Quezon Province in Calabarzon Region; Bohol, Cebu, Negros Oriental, and Suquijor provinces in Central Visayas Region; and Marinduque, Occidental Mindoro, Oriental Mindoro, and Romblon provinces in Mimaropa Region.

Officials could update and extend the coverage of weather alerts over the coming days.

Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rain has saturated the soil.

Authorities could issue mandatory evacuation orders for flood-prone communities over the coming days. Disruptions to electricity and telecommunications services are possible where significant flooding or landslides impact utility networks.

Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters. Severe weather could also trigger flight delays and cancellations at regional airports. Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas with heavy rainfall and potential track inundation.

Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities, possible evacuations, and some employees' inability to reach work sites.