[3] The system's tropical cyclone development potential within 24 hours was further upgraded to medium by the JTWC as its broad low-level circulation began to consolidate; however, atmospheric convection was disorganized.

[7] On November 13, at 00:00 UTC, the Japan Meteorological Agency (JMA) assessed that the system had developed into a tropical depression near the Marshall Islands.

[nb 1] Continuing westwards,[9] wind shear decreased, with the JTWC upgrading the system's tropical cyclone development potential within 24 hours to medium on November 14.

[16] 33W made landfall on Hernani, Eastern Samar on November 20, at 17:00 UTC,[11] with the JTWC downgrading it to a disturbance an hour later[12] as the system's convection fragmented.

Now in the Sulu Sea,[11] the system's low-level circulation moved closer to convection,[18] and on November 21, at 12:00 UTC, the JTWC upgraded 33W back to a tropical depression.

[11] On November 22, at 00:00 UTC, both the JMA and the JTWC upgraded 33W to a tropical storm as deep convection covered the system's low-level circulation, with the former assigning it the name Usagi.

[9][12][19] Now in a favorable environment with low wind shear, the system's low-level circulation slowly consolidated and became better defined despite still being partially exposed.

[21] On November 23, an eye appeared on SSMIS microwave imagery,[22] and at 06:00 UTC, the JMA upgraded Usagi to a severe tropical storm.

[23] Later in the day, a combination of land interaction and unfavorable environmental conditions caused Usagi to weaken[11] as its convective structure deteriorated.

[24] Rainbands collapsed[25] as the system turned northwest,[11] and by November 25, both the JMA and the JTWC had downgraded Usagi to a tropical storm[9][12] as central convection weakened.

[33] 88,787 people were mobilized to aid in the storm response,[34] with 1 thousand police officers and officials being prepared in Cần Giờ District.

[42] Rainfall totals in Ho Chi Minh City averaged 300–400 millimetres (12–16 in), with many buildings remaining partially flooded after Usagi's passage.