System 96W intensified overnight in the South China Sea and became Tropical Storm Pakhar during the morning hours of March 29.
NASA's Tropical Rainfall Measuring Mission (TRMM) satellite passed over Pakhar on the same day and saw that it was generating mostly light to moderate rainfall around the entire system, with areas of heavy rain in the southwestern and northeastern quadrants.
Light to moderate rainfall rates were between 0.78 to 1.57 inches (20 to 40 millimeters) per hour and heavy rain was falling at a rate of 2 inches (50 mm) per hour. The banding of thunderstorms has continued to consolidate and strengthen since March 28, which accounts for the cyclone's increase in strength, according to a NASA statement.
On March 29 at 1500 UTC (11 a.m. EDT) Pakhar's maximum sustained winds virtually exploded from 35 knots (40.2 mph/64.8 kph) to 60 knots (69 mph/111 kph) within 12 hours because it is in an environment with lower wind shear and warm sea surface temperatures.
Pakhar is about 300 nautical miles east of Ho Chi Minh City, Vietnam. It is moving to the west-northwest at about 3 knots (3.4 mph/5.5 kph).
Forecasters at the Joint Typhoon Warning Center expect Pakhar to make landfall in central Vietnam, north of Ho Chi Minh City on March 31. Residents should prepare for rough surf along beaches, gusty winds and heavy rainfall.