State weather bureau PAGASA issued Tropical Cyclone Bulletin Number 1 on Tropical Depression "Isang," at 11 a.m. on  Friday, August 22, 2025. 

The Low Pressure Area (LPA) east of Aurora has developed into Tropical Depression Isang (#IsangPH) and made landfall over Casiguran town, Province of Aurora. 

At about 10 a.m., the center of #IsangPH was estimated based on all available data in the vicinity of Casiguran, Aurora (16.3°N, 122.1°E).

• Intensity

Maximum sustained winds of 55 km/h near the center, gustiness of up to 90 km/h, and central pressure of 1002 hPa

• Present Movement

Westward at 15 km/h

• Extent of Tropical Cyclone Winds

Strong winds extend outwards up to 200 km from the center

TROPICAL CYCLONE WIND SIGNALS (TCWS) IN EFFECT

TCWS No.1

(Wind threat: Strong winds)

Warning lead time: 36 hours

Range of wind speeds: 39 to 61 km/h (Beaufort 6 to 7)

Potential impacts of winds: Minimal to minor threat to life and property

Luzon:

Batanes, Cagayan, Isabela, Quirino, Nueva Vizcaya, Apayao, Kalinga, Abra, Mountain Province, Ifugao, Benguet, Ilocos Norte, Ilocos Sur, La Union, Pangasinan, the northern and central portions of Aurora (Casiguran, Dinalungan, Dilasag, Baler, Maria Aurora, Dipaculao, San Luis) and the northern portion of Nueva Ecija (Lupao, Carranglan, Pantabangan, San Jose City)

OTHER HAZARDS AFFECTING LAND AREAS

Heavy Rainfall Outlook

Refer to Weather Advisory issued No. 4 at 11 a.m. on August 22, 2025 for the heavy rainfall outlook due to Tropical Depression ISANG and the Southwest Monsoon.

Severe Winds

The wind signals warn the public of the general wind threat over an area due to the tropical cyclone. Local winds may be slightly stronger/enhanced in coastal and upland/mountainous areas exposed to winds. Winds are less strong in areas sheltered from the prevailing wind direction.

• Minimal to minor impacts from strong winds are also possible within any of the areas under Wind Signal No. 1.

The Southwest Monsoon slightly enhanced by #IsangPH will bring strong to gale-force gusts over the following areas (especially in coastal and upland areas exposed to winds):

• Today (August 22, 2025): Aurora (areas not under Wind Signal) Zambales, Bataan, Metro Manila, CALABARZON, MIMAROPA, Camarines Norte, Camarines Sur, Catanduanes, Burias Island, Western Visayas, Negros Island Region, Central Visayasa, Dinagat Islands, Southern Leyte, Surigao del Norte, and Camiguin.

• Tomorrow (August 23, 2025): Batanes, Cagayan, Ilocos Region, Cordillera Administrative Region, Zambales, Bataan, Tarlac, Pampanga, Bulacan, Metro Manila, Cavite, Rizal, Palawan, Occidental Mindoro, Romblon, Burias Island, Camarines Sur.

• Sunday (August 24, 2025): Kalayaan Islands.

HAZARDS AFFECTING COASTAL WATERS

24-Hour Sea Condition Outlook

No Gale Warning hoisted at this time.

Up to rough seas over the following coastal waters:

• Up to 3.0 m: The seaboards of Batanes and Cagayan.

• Mariners of small seacrafts, including all types of motorbancas, are advised not to venture out to sea under these conditions, especially if inexperienced or operating ill-equipped vessels.

Up to moderate seas over the following coastal waters:

• Up to 2.5 m: The seaboards of Isabela, Ilocos Norte, and Ilocos Sur.

• Up to 2.0 m: The seaboard of Aurora and Zambales; the western seaboards of Bataan and Lubang Island.

• Mariners of motorbancas and similarly-sized vessels are advised to take precautionary measures while venturing out to sea and, if possible, avoid navigation under these conditions.

TRACK AND INTENSITY OUTLOOK

• #IsangPH will move generally westward during the forecast period. On the track forecast, it will traverse Northern Luzon in the next 12 hours, emerge over the West Philippine Sea tonight, and eventually exit the Philippine Area of Responsibility tomorrow (23 August) morning or afternoon.

• #IsangPH is forecast to intensify into a tropical storm tomorrow morning and may reach severe tropical storm category while approach the waters south of Hainan, China. However, intensification into a tropical storm at a much earlier time (e.g., several hours after emerging over the West Philippine Sea) is not ruled out.

Considering these developments, the public and disaster risk reduction and management offices concerned are advised to take all necessary measures to protect life and property. Persons living in areas identified to be highly or very highly susceptible to these hazards are advised to follow evacuation and other instructions from local officials. For heavy rainfall warnings, thunderstorm/rainfall advisories, and other severe weather information specific to your area, please monitor products issued by your local PAGASA Regional Services Division.

The next tropical cyclone bulletin will be issued at 2 p.m. today, August 22, 2025. 

(Courtesy: DOST-PAGASA)