Originating from an area of disturbed weather near the Philippines in mid-August 1985, the system gradually became better organized, and was upgraded into a tropical storm early on August 16.

However, after turning north and crossing the Shanghai Peninsula and the Yellow Sea, Mamie made a second landfall near Yantai as a tropical storm.

After turning northwest and re-entering the Yellow Sea, Mamie moved ashore for the third and final time near Dairen.

Following an increase in banding features and outflow, a Tropical Cyclone Formation Alert (TCFA) was issued by the JTWC that afternoon.

[4][nb 2] On August 16, the tropical storm began to turn northwest in response to the strengthening of a subtropical ridge north of Mamie and a westward-moving mid-latitude cyclone.

[1] At 0000 UTC on August 17, the JTWC classified Mamie as a typhoon while the JMA reported winds of 105 km/h (65 mph), a severe tropical storm.

[1] Mamie only gradually weakened overland, but according to the JMA, the storm's winds had decreased to 105 km/h (65 mph) midday on August 18.

[4] After crossing the Shanghai Peninsula, Mamie entered the Yellow Sea while turning north along the western periphery of a subtropical ridge, and at 0600 UTC, struck Yantai[1] as a minimal tropical storm.

[4] Following a turn towards the northwest, Tropical Storm Mamie briefly emerged into the Yellow Sea before making a third and final landfall just west of Dairen at noon.

[4] Due to interaction with the mountainous terrain of China, Mamie began to dissipate over land, and by 0000 UTC on August 20, the JTWC ceased watching the cyclone.

[6] Shortly after making landfall, Mamie was considered the worst storm to affect northeastern China in 26 years.

[9] After making landfall, Typhoon Mamie dropped 420 mm (17 in) of rain in Liaoning, where the storm flooded 300,000 ha (741,315 acres) of farmland.