NASA-NOAA’s Suomi NPP satellite provided forecasters with a visible image of a weaker and more asymmetrical Tropical Storm Phanfone on Dec. 27 as it continued moving through the South China Sea.

Satellite imagery gives forecasters a look at the structure and strength of tropical cyclones. Visible imagery helps forecasters understand if a storm is organizing or weakening. If a storm appears more circular in nature it is an indication the storm is consolidating and strengthening. If a storm appears more elongated or asymmetrical, it is a sign that the storm is weakening.

In the visible image captured by Suomi NPP’s Visible Infrared Imaging Radiometer Suite (VIIRS) instrument, Phanfone appeared more asymmetrical.

Forecasters at the Joint Typhoon Warning Center in Pearl Harbor, Hawaii noted that Phanfone is being affected by vertical wind shear, which is a factor in elongating the storm. Wind shear are winds around the storm that blow against it at different levels in the atmosphere. The storm is also being weakened by dry air moving into it from the west. Dry air saps the ability for thunderstorms to form, and thunderstorms make up a tropical cyclone.

At 10 a.m. EST (1500 UTC) on Dec. 27, Phanfone’s maximum sustained winds had dropped to 50 knots. It was located in the South China Sea, near latitude 15.0 degrees north and longitude 115.9 degrees east, approximately 461 nautical miles east of Da Nang, Vietnam.

Phanfone is moving across the South China Sea in a westerly direction and is continuing to weaken. The forecasters at the Joint Typhoon Warning Center expect the storm to dissipate by Dec. 29, just off the coast of Vietnam.

Tropical cyclones and hurricanes are the most powerful weather events on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.

Rob Gutro
NASA’s Goddard Space Flight Center

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https://www.windy.com/-Hurricane-tracker/hurricanes?satellite,13.881,108.831,5,internal

Now the storm has moved into the South China Sea and NASA’s Terra satellite captured an image of the tropical cyclone.

On Dec. 26, 2019, the MODIS instrument that flies aboard NASA’s Terra satellite provided a visible image of Tropical Storm Phanfone re-strengthening in the South China Sea.

Phanfone’s maximum sustained winds peaked near 95 knots on Dec. 25 at 4 a.m. EST (0900 UTC) as it passed through the Philippine archipelago.

On Dec. 26, 2019, the Moderate Imaging Spectroradiometer or MODIS instrument that flies aboard NASA’s Terra satellite provided a visible image of Phanfone that showed the storm maintained its circular shape after crossing the Philippines. A rounded shape of a tropical cyclone indicates an organized storm.

The MODIS image revealed bands of thunderstorms spiraled into the low-level center of circulation.

At 10 a.m. EST (1500 UTC) on Dec. 26, the Joint Typhoon Warning Center noted that Tropical Cyclone Phanfone was located near latitude 14.0 degrees north and longitude 117.4 degrees east, about 554 nautical miles east-southeast of Da Nang, Vietnam. Maximum sustained winds were 75 knots (86 mph/139 kph). Phanfone is moving to the northwest.

Phanfone is forecast to begin a weakening trend and move toward Hainan Island, China. After two days, the storm is expected to weaken to a tropical depression.

NASA’s Terra satellite is one in a fleet of NASA satellites that provide data for hurricane research.

Tropical cyclones and hurricanes are the most powerful weather events on Earth. NASA’s expertise in space and scientific exploration contributes to essential services provided to the American people by other federal agencies, such as hurricane weather forecasting.

Rob Gutro
NASA’s Goddard Space Flight Center

Related content

• NASA Analyzes Tropical Cyclone Phanfone’s Water Vapor Concentration
• What’s the difference between a hurricane, typhoon, cyclone and tornado
• What is the difference between sustained winds and wind gusts

https://www.windy.com/-Hurricane-tracker/hurricanes?satellite,13.881,108.831,5,internal