Tropical Storm Mun (04W) - Tropical Cyclone Advisory #12, 0000 UTC 7/7/25

…Mun weakening over increasingly cold waters…

Current storm information:

• Position: 35.0°N 148.9°E

• Movement: N at 5 knots (10 km/h)

• Intensity: 45 knots (85 km/h)

• Central pressure: 992 hPa

Trend:

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

Watches and warnings:

• There are no land-based watches or warnings in effect.

Hazards affecting land:

• None.

Discussion:

Mun’s satellite presentation has continued to degrade since the previous advisory. Convection associated with the tropical cyclone has become increasingly shallow and displaced to the south of the circulation center by strong upper-level northeasterly shear. The circulation itself is mostly exposed and becoming elongated from north to south, and is embedded in an increasingly dry air mass. Mun is also becoming detached from the upper-level trough it had been under for the last couple of days, which is allowing the system to feel the full force of the shear. The intensity is lowered to 45 kts, which could be generous given Dvorak fixes ranging from T2.5 to T3.0. 

Mun has moved over the northern edge of the 26°C isotherm in the subtropical Pacific, and SSTs are expected to get steadily colder as it moves further north. Between increasingly cold waters and powerful shear, Mun will likely cease generating convection during the next 12 hours or so, which will result in Mun becoming a post-tropical cyclone as soon as tonight. The post-tropical cyclone is forecast to merge with a large extratropical low pressure system moving off Sakhalin Island on Tuesday. The forecast includes a point at 48 hours, but it’s very likely Mun will have ceased to be a distinct entity by then.

Forecast positions and maximum winds

• 00 hrs: 35.0°N 148.9°E – 45 kts

• 12 hrs: 36.5°N 148.6°E – 35 kts Post-tropical

• 24 hrs: 38.2°N 148.9°E – 30 kts Post-tropical/remnant low

• 48 hrs: 42.0°N 158.5°E – 30 kts Post-tropical/remnant low

• 72 hrs: Absorbed by larger extratropical low