Tropical Storm Nari (#06W) – Tropical Cyclone Advisory #7: 0000 UTC 14 July 2025

…Nari losing tropical characteristics… …Strong winds occurring along the eastern coast of Honshu…

Current storm information:

• Position: 34.0°N 141.7°E

• Movement: N at 18 knots (30 km/h)

• Intensity: 45 knots (85 km/h)

• Central pressure: 982 hPa

Trend:

• Weakening is forecast during the next 24 hours, and Nari is expected to become a post-tropical cyclone tonight.

Watches and warnings:

• Storm warnings and high wave warnings are in effect for eastern Fukushima, Ibaraki, and northeastern Chiba prefectures.

• Gale, storm, and heavy surf advisories are in effect along much of the eastern coasts of Honshu and Hokkaido.

• Yokosuka Naval Base is under TCCOR Storm Watch.

Hazards affecting land:

• Nari is expected to produce strong winds, heavy surf, and heavy rain along the eastern coasts of Honshu and Hokkaido today and tonight. 

• 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:

Extratropical transition is well underway as Nari begins to parallel the eastern coast of Honshu. Most of the central convection associated with Nari has dissipated, with only a few puffs of convection here and there. The circulation center is fully exposed with a substantial amount of dry air entrained within it. In addition, there is a well-defined cold front forming to the south of Nari’s center, while Nari’s outflow is becoming entangled within a stationary front to the north. JMA has an intensity estimate of 50 kts, but there are no observations or estimates that support an intensity of that high. The current intensity is listed as 45 kts, hedged between Dvorak estimates of T3.0 to T3.5 and lower CIMSS ADT and D-PRINT estimates of 37 and 40 kts.

Nari will soon be moving over much colder waters. Although it is currently in an area of low shear, the cooler waters will likely put an end to Nari’s efforts to produce organized convection, and interaction with frontal boundaries should cause Nari to rapidly become a post-tropical cyclone tonight. The post-tropical cyclone will be around for a while - it should steadily weaken as it races northward, then northeastward. As it approaches the International Date Line, Nari will interact with another extratropical low over the Bering Sea, and this will result in Nari restrengthening to gale force as it moves over the Aleutian Islands by the end of the forecast period. 

Forecast positions and maximum winds

• 00 hrs: 34.0°N 141.7°E – 45 kts

• 12 hrs: 38.9°N 142.8°E – 35 kts Post-tropical/extratropical

• 24 hrs: 44.1°N 145.5°E – 30 kts Post-tropical/extratropical

• 48 hrs: 49.2°N 156.5°E – 30 kts Post-tropical/extratropical

• 72 hrs: 48.2°N 175.5°E – 35 kts Post-tropical/extratropical

• 96 hrs: 49.5°N 172.5°W – 35 kts Post-tropical/extratropical

• 120 hrs: 52.5°N 166.5°W – 35 kts Post-tropical/extratropical