NASA watches as Vietnam braces for Tropical Storm Sonca

NASA's Aqua satellite took a look at an elongated Tropical Storm Sonca in the South China Sea as it approached Vietnam where it is expected to make landfall. Tropical Depression 08W strengthened into a tropical storm on July 23 and was renamed Sonca.

On July 24 at 1:45 a.m. EDT (05:45 UTC) the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA's Aqua satellite captured a visible-light image of Tropical Storm Sonca approaching Vietnam. Sonca appears slightly elongated in the visible imagery. Forecasters at the Joint Typhoon Warning Center who looked at Sonca with multispectral satellite imagery noted that the central convection and thunderstorms associated with the storm were displaced slightly to the west of the center as a result of wind shear. That displacement makes the storm appear somewhat elongated on visible imagery.

That easterly wind shear is weakening, however, which will allow Sonca to strengthen slightly before it makes landfall just south of the city of Vinh. Vinh is the capital of Ngh? An Province and is located on the North Central Coast.

At 5 a.m. EDT (0900 UTC) on July 24, Sonca's maximum sustained winds were near 46 mph (40 knots/74 kph). It was centered near 17.0 degrees north latitude and 110.9 degrees east longitude. That's about 161 miles east-northeast of Da Nang, Vietnam. Sonca was moving west at 5.7 mph (5 knots/9.2 kph).

Warnings and watches stretch from the North Bacbo Gulf in northern Vietnam to Cau Mau to Binj Thujan in the south.

Sonca is forecast to strengthen to 57 mph (50 knots/92 kph) before making landfall in central Vietnam on July 25.