We often associate the cold with sadness and distance. Walking the streets alone in the cold weather triggers emotional responses among people. In the Philippines, the cold typically heightens during February. It is the season for “hugot” or emotive lines. But have you ever wondered why February marks the coldest time in the Philippines?
Based on historical climate data (1900 through 2012), the months of January to February are among the coldest months in the Philippines. It is during this time when the Northeast Monsoon, locally known as amihan, nears its peak. It is associated with the cool, dry air blowing from the polar region of Siberia, Mongolia and the Northern reaches of the Chinese mainland where polar air is consequently pushed clockwise and downward by a strong anticyclone (high pressure) system.
Typically, the amihan wind cycle persists during the months of October through late March.
It brings about cooler temperatures and blustery winds. These prevail from the north and eastern areas and some occasional light drizzles may also be experienced. Much to most people’s liking, amihan also carries generally fair weather with periods of cloudless skies.
For many of us who live in the tropics, we are used to humid and hot conditions, which is why the cool and fair weather brought by amihan is desirable. However, despite being suitable for some, it can spell treacherous sea conditions. It makes sea travel challenging for mariners and fisherfolk, especially those living along the exposed seaboards of Luzon and Visayas.
Cold surge
A cold surge during amihan is distinctly referred to as a steep rise of surface pressure, coupled with a sharp drop of surface temperature, and a strengthening of northerly surface winds. The effects will also depend on the complex orography (physical geography in relation to existence of mountains) and geographical profile of a certain area.
The cold surge originates from Lake Baikal, located in southeastern Siberian region deep in the Russian subcontinent during winter. When the average sea level pressure exceeds 1,030 hectopascals (a unit of pressure) from late November to early March, it creates an anticyclone which is enhanced by the surrounding mountains that prevent the cold air from flowing away.
Another characteristic of the Siberian high is its wind profile that goes down into the river valleys. Katabatic winds refer to drainage winds — those that have high density, and come from higher elevations moving downwards a slope via gravitational pull.
Meanwhile, to the east along the Pacific Coast, there is a belt of very strong northerly winds. The offshore flow is known as the winter monsoon.
In the Philippines, the effects will be a gradual cooling of surface temperature, bringing notably cold and dry air. However in some cases, it also brings rainfall. In the past few weeks, we have already experienced chilling temperatures of about 10.1 degrees Celsius in Baguio City, or even lower temperatures in upper elevations of Benguet and Mt. Province.
In Metro Manila, the lowest temperature on record so far stands at 18.5 degrees Celsius (February 1).
This cool-dry season also brings dangerous sea conditions, however, especially along the exposed shores of the country, particularly over Batanes and Babuyan Island Groups, Ilocos provinces, Cagayan, Isabela, and across the inland waters of the archipelago, particularly in MIMAROPA, the Bicol region and the Visayas. Being weather-aware is the first step to becoming #WeatherWiser!
