A newly named tropical depression, Mirasol, formed just off the eastern coast of Luzon on Tuesday, prompting the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) to raise Tropical Cyclone Wind Signal No. 1 across portions of northern Luzon. The system is expected to move inland early Wednesday morning, bringing widespread rainfall to northern and central Luzon before exiting toward the Luzon Strait by late Wednesday night or Thursday morning.
According to PAGASA’s latest advisory, Mirasol is currently moving west-northwest at about 15 kilometers per hour with maximum sustained winds of 45 kilometers per hour near the center and gusts up to 55 kph. The system is forecast to make landfall along the Isabela coast before tracking across the Cagayan Valley, then emerging over water between Batanes and Taiwan. Once back over water, Mirasol could strengthen into a tropical storm and possibly reach typhoon intensity as it moves northwest into the open waters of the western North Pacific.
Rainfall, Not Winds, Pose Greatest Threat
Meteorologists stress that the main hazard from Mirasol will be heavy rainfall, not destructive winds.
“While the core winds of this system are not expected to be damaging at this time, what we are looking at is a broad swath of heavy precipitation across northern Luzon,” said meteorologist Robert Speta. “Localized squalls may occur near the center, but widespread flooding rains will be the primary threat.”
Forecast guidance from both the European Centre for Medium-Range Weather Forecasts (ECMWF) and the Global Forecast System (GFS) shows 50 to 150 millimeters of rain falling from Wednesday through Thursday over the Cagayan Valley and the eastern slopes of the Sierra Madre mountains. Higher localized totals are possible along mountainous terrain where orographic lifting enhances precipitation.
PAGASA has also warned of potential flooding and landslides, particularly in low-lying and mountainous areas that have experienced persistent rainfall over recent weeks.
Timeline: When and Where Impacts Are Expected
Mirasol is forecast to make landfall around dawn on Wednesday near Isabela province, then track inland across the northern part of Luzon during the day. The system’s low-level center may weaken slightly as it crosses the Sierra Madre, but rainfall will continue to spread out across much of northern and central Luzon.
By Wednesday afternoon into evening, widespread moderate to heavy rainfall is expected across both Region II (Cagayan Valley) and Region I (Ilocos Region), including the provinces of Cagayan, Isabela, Ilocos Norte, and Ilocos Sur.
By Thursday morning, as Mirasol exits into the Luzon Strait, the system’s core rainfall is expected to taper over northern Luzon. However, the broader southwest flow behind the depression will likely redevelop afternoon convection along the western slopes of Luzon, including La Union, Pangasinan, and Zambales.
“Even though the center of Mirasol may be gone by then, lingering moisture and afternoon instability will keep showers in the forecast through Thursday and Friday,” Speta said. “The southwest flow wrapping behind the system could also send scattered showers as far south as Palawan and Metro Manila by late in the week.”
A brief lull in widespread rainfall is possible by late Friday into Saturday as drier air filters in from the north. However, forecasters caution that the ground will likely remain saturated, leaving the region more vulnerable to localized flooding if additional rainfall occurs.
Monsoonal Pattern Continues
The development of Mirasol fits into a broader monsoonal pattern that has dominated the western Pacific in recent weeks. Warm sea surface temperatures combined with a weak La Niña have fueled persistent troughing across the region, allowing multiple low pressure areas to form and move across the Philippines in succession.
“We’ve had several named systems over the last month and a half, and even when we don’t have a typhoon, the moisture just keeps coming,” Speta said. “The energy is spread out along this trough, and it’s been feeding repeated rainmakers.”
Mirasol is the latest in a string of systems to affect the region, and while its winds may not be strong, its timing during the peak of the rainy season increases the risk of hydrological impacts.
Safety and Preparedness
Authorities are urging residents in areas under Signal No. 1 to prepare for heavy rainfall and possible flooding. PAGASA advises the public to monitor official bulletins for possible upgrades in warning signals if Mirasol strengthens, and to be alert for advisories from local disaster risk reduction offices regarding possible evacuations or road closures.
Meteorologists emphasize that checking official sources such as PAGASA should be a top priority when making safety decisions.
“I’ll always do my best to explain what’s happening and what it means,” Speta said. “But when it comes to evacuations or emergency actions, those decisions must come from your local officials and PAGASA.”
Looking Ahead
After emerging into the Luzon Strait late Thursday, Mirasol is expected to move northwest into the open western North Pacific. There, forecasters say conditions appear favorable for intensification into a tropical storm, and possibly even a typhoon, as the system encounters warmer waters and reduced wind shear.
While this track would take the storm away from the Philippines, its departure could draw additional southwest monsoon moisture back over western parts of the country, potentially keeping scattered showers in the forecast into the weekend.
Bottom line:
- Landfall expected Wednesday morning near Isabela
- Heavy rain across Cagayan Valley and northern Luzon Wednesday into Thursday
- Flood and landslide risk in low-lying and mountainous areas
- Gradual clearing possible Friday into Saturday
PAGASA continues to issue updates on Tropical Depression Mirasol, and residents are urged to stay tuned to official forecasts as the system moves across Luzon.