Tropical Depression (#93W) – Tropical Cyclone Advisory #1: 1200 UTC 1 August 2025

……Tropical depression well to the east of Okinawa could become a tropical storm over the weekend… …Not expected to be a threat to land……

Current storm information:

• Position: 25.7°N 135.3°E

• Movement: E at 14 knots (25 km/h)

• Intensity: 30 knots (55 km/h)

• Central pressure: 996 hPa

Trend:

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

Discussion:

The tropical depression located well east of Okinawa is not particularly well organized, but available data suggests its circulation is becoming better defined. The system, basically the remnant of the large monsoon gyre that dominated the East China and Philippine Seas for the past couple of weeks, still has some monsoonal characteristics. The circulation is fairly broad and convection is wrapping rather loosely into it from the south and west. There is little in the way of convection directly over the center or to the northwest, likely due to northeasterly subsidence from Tropical Storm Krosa’s outflow. Although the wind field is quite broad, HYSAT scatterometer data from around 0830 UTC suggests the depression is producing winds of 30 kts.

TD 93W is currently embedded within strong southwesterly flow along the western periphery of a mid- to upper-level ridge anchored over the west central Pacific, which explains its unusual eastward motion. This steering flow is the same as what is currently steering Krosa, and as a result TD 93W is more or less forecast to follow Krosa during the next few days. Since 93W will be involved with the same upper-level trough Krosa is, the environment is expected to be only marginally favorable for development, and it will become even less so over the weekend as it encounters the large pool of cooler waters left behind by Krosa earlier this week. Therefore, only some slow strengthening appears likely as 93W rounds the subtropical ridge and becomes swept up into the mid-latitude westerlies. As Krosa weakens, so will the shear, and 93W could strengthen a little more toward the end of the forecast period.

Forecast positions and maximum winds

• 00 hrs: 25.7°N 135.3°E – 30 kts

• 12 hrs: 27.7°N 137.2°E – 30 kts

• 24 hrs: 30.1°N 138.9°E – 35 kts

• 48 hrs: 34.7°N 144.7°E – 35 kts

• 72 hrs: 35.2°N 153.4°E – 35 kts

• 96 hrs: 35.1°N 157.5°E – 40 kts

• 120 hrs: 37.5°N 159.9°E – 40 kts