Philippines: Adverse weather forecast across parts of northern Luzon Island through at least Oct. 22

Event

A combination of weather systems are expected to bring adverse weather conditions to parts of northern Luzon and the Babuyan and Batanes islands through at least Oct. 22. As of Oct. 19, the Philippine Atmospheric, Geophysical, and Astronomical Administration (PAGASA) have issued a weather advisory due to the presence a shear line which is forecast to bring moderate to heavy rainfall to Cagayan (including the Babuyan Islands), Ilocos Norte, Batanes, and Apayao provinces Oct. 19-20. The heavy downpours could trigger flooding and landslides in parts of the affected areas. As of Oct. 19, PAGASA has issued moderate general flood advisories (the lowest level on a four-tier scale) for Ilocos Norte and Cagayan provinces.

A low pressure area currently located to the east of Luzon in the Philippine Sea, named Tropical Depression Obet by PAGASA, is forecast to develop into a tropical storm and approach the far north of Luzon by Oct. 21. The storm system is forecast to bring further moderate to heavy rainfall with intense downpours at times to the Babuyan Islands, Apayo, Ilocos Norte, and northern Cagayan Oct. 21 and light to moderate rainfall with heavy downpours at times to Batanes, northern Ilocos Sur, Abra, Kaling and the rest of Cagayan Oct. 21 and to Batanes, the Babuyan Islands, Apayao, Ilocos Norte, northern Abra, and northern Ilocos Sur Oct. 22.

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

Much of the affected area is currently recovering from widespread flooding and associated disruptions following the passing of tropical storm Neneng and tropical depression Maymay. Neneng passed over the Babuyan Islands early Oct. 16 and Maymay dissipated as it passed over central Luzon Oct. 13. Around 27,000 people in Cagayan Valley Region were affected by Neneng, which caused thousands of people to evacuate and damaged dozens of roads. Other parts of far northern Luzon also experienced disruption and evacuations during the passing of Neneng and similar impacts occurred in areas further south due to Maymay. Further sustained rainfall associated with the approaching weather systems could trigger additional flooding in areas where river levels are already high and the ground is saturated, as well as hamper ongoing recovery efforts.

Hazardous Conditions
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 located 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 rainfall 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.

Transport
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 airports in the region, including Tuguegarao Airport (TUG) and Laoag International Airport (LAO). Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas that see 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.

Advice

Monitor local media for weather updates and related advisories. Confirm all transport reservations and business appointments before travel. Make allowances for localized travel delays and potential supply chain disruptions where flooding has been forecast. Do not drive on flooded roads. Charge battery-powered devices in the case of prolonged electricity outages.

Resources

Philippine Atmospheric, Geophysical, and Astronomical Administration (PAGASA)