It doesn't have a name, nor a forecast track, yet when it hits, the heavy rains it brings can paralyze the Philippines' mega cities. It's called Habagat or Southwest Monsoon and it is most felt during the middle of the year.
On Wednesday, Typhoon Fabian (In-Fa) was on its way out of the country and didn't even make landfall, yet millions woke up to downpours. That's the Habagat, stirred by the exiting storm, said PAGASA.
Habagat is a major wind system which develops when it's summer in the northern hemisphere and winter in the southern hemisphere, said PAGASA Climate Monitoring Officer in Charge Annalisa Solis.
Habagat winds blow from the southwest, hence its English name. When the wind patterns switch close to the Christmas months, the prevailing weather system is the Amihan or Northeast Monsoon, which is also wet.
"Kapag winter po sa southern hemisphere, malamig siya so 'yung malamig na hangin, pupunta siya sa mas mainit na hangin which is dito po sa northern hemisphere," Solis told reportr.
"Since tayo ay nasa gitna ng karagatan, 'yung hangin na 'yan na mainit na posibleng magdala ng pag-uulan dahil siya ay tatawid o dadaan sa malaking bahagi ng dagat, nagkukuha siya ng maraming moisture," Solis said.
Warm winds from the southwest cross the equator onto the Philippines. This happens during the summer season in the northern hemisphere, usually from June to August, hence the "summer monsoon."
It first reaches the western section of Luzon, including portions of Panay Island and Iloilo. When PAGASA records continuous rains over several days, it declares the onset of the rainy season. It also signals that the Habagat is here.
Habagat can be destructive, when it mixes with typhoons
When a weather disturbance forms near the southwest winds, it will interact and enhance the monsoon. It does not have to be inside the Philippine area of responsibility to bring rains in the country, just like what's happening with Typhoon Fabian.
This phenomenon recurs frequently in the Philippines. Remember August 2012, when Tropical Storm Haikui located outside the country northeast of Taiwan enhanced the southwest monsoon affecting Luzon and Visayas? The Marikina and Tullahan rivers swelled. After five days of rains, 112 were killed, according to the National Disaster Risk Reduction and Management Council (NDRRMC).
In 2013, the Habagat was enhanced by Tropical Storm Maring, bringing floods over the National Capital Region and nearby provinces. Some 32 people died due to the storm.
In 2018, three storms -- Henry, Inday, and Josie -- enhanced the habagat. Over 1.1 million individuals were affected by floodings. Four people were reported dead in its aftermath.
Then there's the epic floods spawned by Ondoy (Ketsana) in 2009. It's not a particularly strong storm based on wind speed, but it stirred the monsoon.
Here is a guide from PAGASA on what to do during and after flooding:
DURING THE FLOOD
- Avoid areas subject to sudden flooding.
- Do not attempt to cross rivers of flowing streams where water is above the knee.
- Beware of water-covered roads and bridges.
- Avoid unnecessary exposure to the elements.
- Do not go swimming or boating in swollen rivers.
- Eat only well-cooked food. Protect leftovers against contamination.
- Drink clean or preferably boiled water only.
AFTER THE FLOOD
- Re-enter establishments with caution using flashlights, not lanterns or torches. Flammables may be inside.
- Be alert for fire hazards like broken wires.
- Do not eat food and drink water until they have been checked for floodwater contamination.
- Report broken utility lines (electricity, water, gas, and telephone) to appropriate agencies authorities.
- Do not turn on the main switch or use appliances and other devices until these have been checked properly by an electrician.
- Consult health authorities for immunization requirements.
- Do not go to disaster areas. Your presence might hamper rescue and other emergency operations.