The Philippines is experiencing a complex weather pattern driven by the convergence of a cold surge, the intertropical convergence zone (ITCZ), and a shear line. These systems are creating highly variable weather conditions, with heavy rainfall in some areas and dry conditions in others. Here, we explore the latest updates, forecasts, and the science behind these weather phenomena.
The Current Situation
A cold surge continues to flow southward, with open-cell cumulus clouds visible over Japan on satellite imagery, signaling the extent of this cold air mass. As the surge pushes further south, it interacts with the ITCZ and a shear line, creating a stationary boundary over Southern Luzon. This boundary is where cold, dry air from the north meets warm, moist tropical air, resulting in unstable weather conditions.
Meteorologist Robert Speta reports that while no organized tropical systems or low-pressure areas are currently forming, the convergence of these systems is enough to cause significant rainfall in certain regions. “This interaction dominates our forecast,” Speta explains, “but thankfully, no typhoon threats are expected in the extended outlook.”
Regional Rainfall Impacts
The heaviest rainfall is concentrated in Southern Luzon, including the Bicol region, Aurora, and eastern parts of Mindoro. Rainfall totals in these areas could reach 200-300 millimeters in the coming days, with localized flooding a possibility. Other affected regions include Eastern Samar and Eastern Leyte, which are experiencing significant moisture flow from the ITCZ. However, not all areas are equally impacted.
In Cebu and parts of Central Visayas, conditions remain relatively dry due to the shielding effect of surrounding islands. This geographical phenomenon highlights the variability of weather in the archipelago, where some areas can experience heavy rains while others remain sheltered.
The Science Behind the Weather
The cold surge originates from Siberia, bringing cold, dry air into East Asia and the Western Pacific. As this air mass moves southward, it interacts with the ITCZ—a zone of converging trade winds that generates clouds and precipitation. The shear line, which acts as a boundary between these air masses, becomes a focal point for rainfall and storm activity.
This setup is typical during the Northeast Monsoon (Amihan) season, which often brings cooler temperatures to the Philippines, especially in elevated areas. For instance, Baguio City has recorded lows of 15°C, with nearby Benguet seeing single-digit temperatures at night. These conditions are a stark contrast to the warmer, tropical weather experienced further south.
Extended Forecast
Looking ahead, most precipitation will remain concentrated south of Metro Manila through the weekend. Hourly forecasts suggest that rainfall will continue in Southern Luzon, Visayas, and Palawan, with temperatures ranging from 28°C to 30°C. Meanwhile, northern regions such as Ilocos Norte and Cagayan Valley will stay relatively dry, with cooler highs of 24°C to 27°C.
Large waves are expected along the eastern coasts of Luzon and Visayas due to strong northeasterly winds. Travelers and coastal residents should exercise caution, especially in areas prone to high surf and rough seas.
Long-Range Outlook
The Climate Prediction Center (CPC) forecasts stable conditions in the Western Pacific over the next two weeks. Ensemble models confirm the absence of tropical cyclone activity, providing some relief for communities still recovering from past storms.
Speta notes that while typhoon activity is low, the cold surge and associated rainfall could still have localized impacts. “It’s always important to monitor these systems closely,” he says, urging residents to stay updated through local weather agencies.
Frequently Asked Questions (FAQ)
1. What is a cold surge?
A cold surge is a mass of cold, dry air that originates from Siberia and flows southward during the Northeast Monsoon season. It often brings cooler temperatures and stronger winds to East Asia and the Western Pacific, including the Philippines.
2. What is a shear line?
A shear line is a weather boundary where cold, dry air meets warm, moist air. This interaction creates instability, leading to cloud formation and precipitation. In the Philippines, shear lines often cause localized heavy rainfall during the Amihan season.
3. What is the ITCZ?
The intertropical convergence zone (ITCZ) is a region near the equator where trade winds from both hemispheres meet. This zone is characterized by frequent cloudiness and precipitation, and it shifts location depending on the season.
4. Why is Cebu experiencing dry weather while other areas are rainy?
Cebu and other central islands are often sheltered from prevailing weather systems due to their geographical location. Surrounding islands can block moisture-laden winds, reducing rainfall in these areas.
5. Are there any tropical cyclones expected?
No tropical cyclones are expected in the Western Pacific over the next two weeks, according to the latest forecasts. However, localized weather systems, such as the cold surge and shear line, can still produce heavy rainfall in certain areas.
6. How can residents prepare for heavy rainfall?
Residents in affected areas should monitor updates from local weather agencies and prepare for potential flooding. It’s also advisable to secure loose items, check drainage systems, and stock up on emergency supplies.
7. What areas are most affected by the current weather?
Southern Luzon, including the Bicol region, Aurora, and eastern Mindoro, is experiencing the heaviest rainfall. Parts of Eastern Samar and Eastern Leyte are also affected. Northern regions, such as Metro Manila and Ilocos Norte, remain relatively dry.
8. Are there any travel advisories?
Coastal residents and travelers should exercise caution due to high waves along the eastern seaboard of Luzon and Visayas. Road travel in areas experiencing heavy rainfall may also be affected by flooding or reduced visibility.
9. What temperatures can we expect?
Temperatures in affected areas range from 28°C to 30°C in Southern Luzon and Visayas. Cooler temperatures of 24°C to 27°C are expected in northern regions, with Baguio City recording lows of 15°C.
10. How can I stay updated?
For the most accurate and timely updates, monitor weather bulletins from PAGASA or other local meteorological agencies. You can also follow Western Pacific Weather for additional insights and forecasts.
Acknowledgements
This update is made possible by the support of Patreon members and sponsors like Frontrunner Financial, an international firm specializing in tax and financial planning for expatriates. Speta extends his gratitude to all supporters and viewers of Western Pacific Weather for their continued engagement.
Stay safe, and as always, keep an eye on the skies.