Post-Tropical Cyclone Nari (06W) – Tropical Cyclone Advisory #8 (FINAL): 1200 UTC 14 July 2025

…Nari becomes a post-tropical cyclone… …This is the last advisory…

Current storm information:

• Position: 39.7°N 142.7°E

• Movement: N at 30 knots (55 km/h)

• Intensity: 40 knots (75 km/h)

• Central pressure: 989 hPa

Trend:

• The post-tropical cyclone is forecast to weaken during the next 24 hours.

Watches and warnings:

• Storm warnings and high wave warnings are in effect along the northeastern coast of Honshu and the southeastern portion of Hokkaido.

• Yokosuka Naval Base is under TCCOR Storm Watch.

Hazards affecting land:

• The post-tropical remnants of Nari could produce storm-force winds, heavy surf, and heavy rain across the Aleutian Islands on Wednesday and Thursday. For additional information, including possible warnings, refer to products from your local weather office.

• U.S. military interests can get additional information from the Stars & Stripes Pacific Storm Tracker: https://www.stripes.com/theaters/asia_pacific/storm_tracker/ 

Discussion:

Nari has not generated any substantial convection for about 18 hours now, and the center of circulation is moving over dramatically colder waters off the eastern coast of Honshu. Although cyclone phase analysis indicates that Nari still has a deep warm core, there are well defined fronts very close to its center, with another cold front impinging upon the system from the west. In addition, surface observations from Japan indicate that gale-force winds are not reaching the coast, and Oceansat and HYSAT scatterometer data indicates the wind field has taken on an extratropical structure with the strongest winds extending far to the south and east of the center. All of this means that Nari is now a gale-force post-tropical cyclone, and this is the last advisory.

Post-tropical Nari is expected to be around for a while, and the Aleutian Islands and southwestern Alaska should monitor its progress. The cyclone is forecast to continue rocketing to the north during the next few hours before turning northeast over the Kuril Islands as it rounds the unseasonably strong subtropical ridge over the north central Pacific. Post-tropical Nari will likely weaken below gale force during the next couple of days as the circulation becomes stretched out, but by Wednesday, interaction with a large low over the Bering Sea will cause Nari to strengthen again as it exits the basin and moves over the Aleutians on Thursday.

This is the last advisory on Nari. For further information regarding Nari’s progress as an extratropical system, refer to products from the Japan Meteorological Agency and the U.S. National Weather Service.

Forecast positions and maximum winds

• 00 hrs: 39.7°N 142.7°E – 40 kts Post-tropical/extratropical

• 12 hrs: 44.6°N 144.5°E – 30 kts Post-tropical/extratropical

• 24 hrs: 47.9°N 149.9°E – 30 kts Post-tropical/extratropical

• 48 hrs: 47.5°N 170.5°E – 30 kts Post-tropical/extratropical

• 72 hrs: 52.5°N 173.2°W – 40 kts Post-tropical/extratropical

• 96 hrs: 57.5°N 178.5°W – 40 kts Post-tropical/extratropical

• 120 hrs: 56.3°N 171.5°W – 35 kts Post-tropical/extratropical