Tropical Depression 16W – Tropical Cyclone Advisory #1: 0000 UTC 7 August 2025

…Tropical Depression 16W nearly stationary near the Northern Mariana Islands… …Expected to begin moving westward later today…

Current storm information:

• Position: 18.4°N 147.8°E

• Movement: Nearly stationary

• Intensity: 25 knots (45 km/h)

• Central pressure: 1007 hPa

Trend:

• Some strengthening is forecast during the next 24 hours, and the depression will likely become a tropical storm by Friday.

Discussion:

Convection associated with the tiny tropical depression located near the northernmost CNMI has continued to become better organized, with a small central dense overcast now located just to the southwest of the circulation center. The center itself is intermittently exposed but well defined, and the system appears to be experiencing some moderate (20-25 kts) northeasterly shear. A recent (2330 UTC) ASCAT-C pass indicated that the system is producing an area of 25 to 30 kt winds in its southern semicircle, and combined with Dvorak fixes of T1.5 to T2.0, JTWC has upgraded the system to Tropical Depression 16W with 25 kt winds.

The forecast is a bit uncertain. Although steering currents are weak at the moment, strong subtropical ridging is expected to build eastward across the Ryukyu Islands and into the northern Philippine Sea. This should cause TD 16W to begin a northwestward motion later today, before turning almost due west on Friday and continuing in that direction through the end of the forecast period. Global models differ significantly in TD 16W’s potential intensity, with GFS and ECMWF ensemble model solutions ranging from TD 16W remaining weak to a very strong typhoon through midweek. Given the small size of the depression, it will likely be very sensitive to environmental changes, and seeing as the environment should generally be favorable, steady to rapid strengthening is forecast with 16W becoming a typhoon by the end of the forecast period. The wind values below are higher than in the JTWC forecast. Confidence in the forecast is fairly low, however.

Forecast positions and maximum winds

• 00 hrs: 18.4°N 147.8°E – 25 kts

• 12 hrs: 18.8°N 147.1°E – 30 kts 

• 24 hrs: 19.4°N 146.2°E – 40 kts 

• 48 hrs: 20.6°N 143.7°E – 50 kts 

• 72 hrs: 20.8°N 140.1°E – 65 kts

• 96 hrs: 20.8°N 135.8°E – 85 kts

• 120 hrs: 20.9°N 131.6°E – 100 kts