Understanding rainfall forecast
CEBU CITY, Philippines—The Philippine Atmospheric Geophysical Astronomical Services Administration has forecast that Typhoon Yolanda can dump 10 millimeters (mm) to 30mm of rain along its path.
The supertyphoon has a diameter of around 600 kilometers, capable of blanketing the whole of Visayas, northern and northeastern Mindanao and Bicol and southern Luzon.
In Cebu City, the Department of Engineering and Public Works (DEPW) of the City Hall said that 50mm of rainfall in a day could cause flooding in areas closer to the Mactan Channel with elevations of zero to 10 meters above sea level. A 50mm rainfall is 2.083mm of rainfall in an hour on the average.
At 10mm of rain, 50mm can be reached in five hours. At 30mm, it can be reached in 1.6 hours.
The DEPW said a 200mm rain in a day can cause severe flooding in low-lying areas and in the city’s waterways. At 10mm, it is 20 hours of continuous rain. At 30mm it is 6.6 hours of continuous rains.
The city’s main waterways, according to the DEPW, are Bulacao River, Tagunol Waterway, Kinalumsan River, Guadalupe River, Estero Parian, Lahug River and Mahiga Creek.
