Severe Tropical Cyclone Thelma was a tropical cyclone that affected Influence northern Australia from 6 December 1998 until 12 December 1998 .

Cyclone Thelma was one of the most intense tropical cyclones to be observed Perception_active off the coast of Australia .

Thelma formed Coming_to_be in the Arafura Sea north of the Northern Territory while intensifying Cause_change_of_strength rapidly into a Category 5 cyclone , passing Motion_directional very near the Tiwi Islands and posing Causation a severe threat to Darwin , but passed Motion_directional by at a distance of .

Thelma was the first known Category 5 cyclone to be observed Perception_active in the Timor Sea , and was also the most intense cyclone to threaten Warning Darwin since Cyclone Tracy on Christmas Eve in 1974 .

Forming Coming_to_be out of a tropical disturbance on November 1 , 1991 , several hundred kilometers north-northeast of Palau , the depression that would become Becoming Thelma tracked Self_motion generally westward .

Hours before moving Motion over the Visayas , Thelma attained Getting its peak intensity with estimated ten-minute sustained winds of 75 km/h ( 45 mph ) and a barometric pressure of 992 mbar ( hPa ; 29.29 inHg ) .

Thelma ultimately succumbed Death to wind shear and degraded Cause_change_of_position_on_a_scale to a tropical depression .

While passing Motion_directional over the Philippines , Thelma 's interaction with the high terrain of some of the islands resulted in Causation torrential rainfall .

This made Thelma the deadliest tropical cyclone in Philippine history , surpassing Cause_change_of_position_on_a_scale a storm in 1867 that killed Killing 1,800 , until later surpassed Cause_change_of_position_on_a_scale by Typhoon Haiyan ( Yolanda ) in 2013 which killed Killing at least 6,300 people .