Tropical Depression 13W – Tropical Cyclone Advisory #3: 1200 UTC 2 August 2025

…Tropical Depression 13W remains poorly organized…

Current storm information:

• Position: 29.6°N 139.6°E

• Movement: NE at 15 knots (25 km/h)

• Intensity: 30 knots (55 km/h)

• Central pressure: 998 hPa

Trend:

• Some slow strengthening is possible during the next 24 hours, and the depression could become a tropical storm on Sunday.

Discussion:

To be quite blunt, Tropical Depression 13W is a very ugly system. It consists of a partially exposed and elongated swirl of low clouds with a few fragmented bands of convection wrapping loosely into it from the east. The depression is embedded within an upper-level trough, which is squeezing the system and preventing convection from wrapping fully into the circulation center. A recent HYSAT scatterometer pass also indicated that the strongest winds associated with the depression are limited to the southeastern quadrant, with very light winds north and west of the center. This scatterometer pass suggested the winds are around 30 kts, so that remains the current intensity.

TD 13W is close to the northwestern periphery of the ridge anchored over the west central Pacific, and so it should gradually turn toward the east-northeast during the day on Sunday. Although the environment appears to be favorable for strengthening with warm SSTs and low shear, the compressed nature of the system and its poorly defined circulation will likely be a check on any significant strengthening. 13W is therefore forecast to only strengthen slightly during the next day or two. By Tuesday, 13W should encounter much cooler waters and begin to interact with a baroclinic zone, and this should result in 13W becoming a post-tropical cyclone by Wednesday.

Forecast positions and maximum winds

• 00 hrs: 29.6°N 139.6°E – 30 kts

• 12 hrs: 32.6°N 141.8°E – 30 kts

• 24 hrs: 35.0°N 145.5°E – 35 kts

• 48 hrs: 37.0°N 153.6°E – 40 kts

• 72 hrs: 37.5°N 159.8°E – 35 kts

• 96 hrs: 40.0°N 164.7°E – 35 kts Post-tropical/extratropical

• 120 hrs: 41.8°N 174.0°E – 35 kts Post-tropical/extratropical