Why does Dagupan record the highest heat index daily?
THE regularity of the occurrence a high heat index in Dagupan City and Pangasinan since 2023 has made many wonder what appears to be a new phenomenon.
Well, here’s a scientific explanation finally from the Provincial Disaster Risk Reduction and Management Office (PDRRMO) .
In its Facebook post on April 16, 2024, PDRRMO said the four factors are: (1) Topography. 2) March Equinox, 3) Easterlies, and (4) its location in the Agno River Valley.
On topography, PDRRMO said Dagupan is a coastal area of the Lingayen Gulf where sea surface temperature has a big influence on climate and weather, therefore, its shoreline has the capacity to store heat or thermal energy that may bring in higher temperature to the surrounding environment.
The March Equinox makes the day longer than the night during summer because half of the earth is facing the sun and that allows longer time and heat beamed on the Philippines, particularly Northern Luzon where Dagupan City and Pangasinan are located.
On the other hand, the easterlies. composed of tropical winds coming from the Pacific Ocean, dominate winds during summer, bring sweltering heat to Dagupan and Pangasinan, consequently raising the level of temperature in these areas.
The last factor is the fact that Dagupan and the adjacent areas in Central Pangasinan are inside the Agno River Valley, where the chances of cloud formation and rains, and the wind that flows into the valley are lesser during summer, and where sun exposure is more intense than in any period of the year.
Meanwhile, analyzing the high heat index of 42 degrees celsius of Dagupan in March 26 and 29, 2023, the highest in the country during those days, Dr. Gerry Bagtasa, a professor at the University of the Philippines, was quoted to have enumerated three reasons why it feels incredibly hot in Luzon—particularly in Dagupan City—during the dry season.
He said, first, the city is in the tropics (or near the equator), and second, there’s longer daytime than nighttime, so there’s longer time to heat up everything again.
The third, is the interaction between winds coming from the east or from the Pacific and the mountains, creating what is known as ‘Foehn ‘winds, which are warm dry air rolling down the lee or leeward side of mountains (the opposite of prevailing winds).
Dr. Bagtasa said Foehn winds are what make the air hot and not the easterly winds but because of the Sierra Madre Mountains to the east. (Leonardo Micua)
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