tropical cyclones in PH

Merger possible as Tropical Storm Maring, Tropical Depression Nando interact

Acor Arceo
Merger possible as Tropical Storm Maring, Tropical Depression Nando interact

TROPICAL CYCLONES. Satellite image of Tropical Storm Maring (Kompasu) and Tropical Depression Nando as of October 9, 2021, 6:30 am.


Tropical Storm Maring (Kompasu) and Tropical Depression Nando could merge within 36 hours, says PAGASA early Saturday, October 9

Tropical Storm Maring (Kompasu) intensified further before dawn on Saturday, October 9, as it started to interact with Tropical Depression Nando.

Maring remains a “large tropical cyclone,” said the Philippine Atmospheric, Geophysical, and Astronomical Services Administration (PAGASA).

A merger between Maring and Nando could occur.


Maring now has maximum sustained winds of 85 kilometers per hour from the previous 65 km/h and gustiness of up to 105 km/h from the previous 80 km/h.

The tropical storm was located 875 kilometers east of Catarman, Northern Samar, in the early hours of Saturday.

It continues to move east northeast at 15 km/h.

Though Maring is not yet near land, PAGASA reiterated that the tropical storm is bringing more rain on Saturday.

Moderate to heavy rain

  • Eastern Visayas
  • Dinagat Islands

Light to moderate rain, with at times heavy rain

  • rest of Visayas
  • rest of Caraga
  • Bicol

There may also be light to heavy rain in Palawan and Occidental Mindoro starting Saturday afternoon or evening due to the southwesterlies or winds from the southwest, enhanced by Maring.

Isolated to scattered floods and landslides are possible. (READ: FAST FACTS: Tropical cyclones, rainfall advisories)

Meanwhile, there are still no tropical cyclone wind signals in effect. But due to the “expansive wind field” of Maring, occasional gusts may be experienced in the following areas:

  • Eastern Visayas
  • Caraga
  • Catanduanes
  • Albay
  • Sorsogon

Signal No. 1 could be raised for parts of Northern Luzon beginning Saturday or Sunday, October 10.

The highest possible tropical cyclone wind signal due to Maring remains Signal No. 2.

But PAGASA is not ruling out the possibility of raising tropical cyclone wind signals even in areas outside Northern Luzon, and the possibility of declaring higher wind signals, if there are changes in Maring’s intensity and track – including a potential merger with Nando.

A gale warning was also issued at 5 am on Saturday for the eastern seaboards of Southern Luzon, the Visayas, and Mindanao because of Maring. Waters are rough to very rough, with waves 2.8 to 4.5 meters high.

PAGASA advised fishing boats and other small vessels not to sail, while larger vessels must watch out for big waves.

In the eastern seaboards of the country that are not under the gale warning and in the western seaboard of Luzon, moderate to rough seas are expected on Saturday. Travel is risky for small vessels.

PROJECTED PATH. Forecast track of Tropical Storm Maring (Kompasu) as of October 9, 2021, 5 am.

Before dawn on Saturday, Nando was located 1,105 kilometers east of Northern Luzon.

The tropical depression accelerated while interacting with Maring, moving west at 25 km/h from the previous 20 km/h.

It maintained its strength, with maximum sustained winds of 55 km/h and gustiness of up to 70 km/h.

Nando is unlikely to directly affect weather in the Philippines. There are no rainfall warnings, no tropical cyclone wind signals, and no coastal hazards due to the tropical depression.

Nando is not likely to strengthen, and may even weaken into a low pressure area on Sunday.

PROJECTED PATH. Forecast track of Tropical Depression Nando as of October 9, 2021, 5 am.
Potential merger

Both Maring and Nando are still “embedded within the larger circulation of a monsoon depression.”

“Near-term erratic movement remains likely in the next 24 hours as the circulations of both Maring and Nando interact with each other in a potential merger event,” PAGASA said.

The merger could happen within 36 hours, or by Sunday.

The weather bureau added that Maring is likely to dominate the resulting merger cyclone, since it is stronger than Nando.

The merger cyclone may then intensify and become a severe tropical storm, also within 36 hours.

It may cross the Luzon Strait and pass over or close to Batanes and the Babuyan Islands between Monday evening, October 11, and Tuesday morning, October 12.

But the weather bureau noted that given “the trend of changes” observed, so far, and the “uncertainty” of the Maring-Nando merger, forecasts can still change.

Maring is the Philippines’ 13th tropical cyclone for 2021 and the second for October, while Nando is the country’s 14th for the year and the third for the month.

An average of 20 tropical cyclones form within or enter the Philippine Area of Responsibility each year. (READ: LIST: PAGASA’s names for tropical cyclones in 2021)

These are PAGASA’s latest estimates for the next six months:


  • October – 2 or 3
  • November – 2 or 3
  • December – 1 or 2


  • January – 0 or 1
  • February – 0 or 1
  • March – 0 or 1

The weather bureau is also monitoring the possible emergence of La Niña in the fourth quarter of 2021. –

Acor Arceo

Acor Arceo is the head of copy and editorial standards at Rappler. Trained in both online and TV newsrooms, Acor supervises Rappler’s coverage of disasters, handles the business desk, and ensures consistency in editorial standards across all sections.