Sunday, January 29, 2012

TS Sendong (Washi)

Anatomy of a Disaster

Track map of Tropical Storm Washi. The points show the location of the storm at 6-hour intervals.

On December 12, 2011, a developing area of low pressure had persisted about 945 km south-southeast of Guam. Situated along the southern edge of a subtropical ridge, the system tracked steadily westward towards the Philippines. The following day, the system was classified as a tropical depression.  Maintaining a westward track, the depression was forecast to intensify slowly over the following three days. By December 14, convection redeveloped over the low and the system  has attained tropical storm status - Tropical Storm Washi (international designation).

Early on December 15, Washi entered the Philippine area of responsibility. Upon doing so, PAGASA began issuing advisories and assigned the cyclone with the local name Sendong. On December 16, Sendong reached its peak strength as a severe tropical storm and made its first landfall along the east coast of Mindanao. Upon landfall, Sendong shifted its path at the last minute. It shifted slightly north and made its landfall in Hinatuan, Surigao Del Sur instead of Boston, Davao Oriental. It passed through Bukidnon, Cagayan de Oro and towards Iligan Bay.

After passing Mindanao, Sendong weakened due to land interaction, but the storm regained its strength quickly in the Sulu Sea. Late on December 17, Sendong crossed Palawan and arrived in the South China Sea, and the system moved out of the Philippine Area of Responsibility on December 18.  Washi weakened to a tropical depression and dissipated on December 19, because of cool, dry air in association with the Northeast Monsoon.

Death and Devastation in Iligan City

Those along large rivers, steep slopes and river valleys are instant catch basins and would act as funnels channeling floodwaters from the mountains to the populated low lying areas of the city. 

Since the rains fell on landslide-prone areas and/or where the natural forest had been illegally logged , the heavy rains were able to run off quickly and create devastating flash floods.


This part of the Philippines is not usually pounded by strong typhoons and the city is unaccustomed to tropical storms and didn't anticipate that a typhoon with a signal number 2 will pour such amount of  rainfall. Sendong was not an especially intense storm but the torrential rains and resulting mudslides caught Iligan off guard.  Since the storm hit in the middle of the night, and affected an unprepared population that had no flood warning system in place, the death toll was tragically high. Hundreds were swept to their deaths in one of the worst calamities to strike the city in decades. In addition to the lives lost, thousand of houses were swept away, destroyed or damaged.

Heavy rains + mudslide + logs/uprooted trees + no flood warning system = Death and Devastation

Let us continue to pray for all the victims of  Typhoon Sendong, especially for those who lost their loved ones.


Iligan Blogger’s Society, Inc.
The Washington Post

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