NASA Sees Pinhole Eye Seen in Weakening Tropical Cyclone Winston
NASA-NOAA's Suomi NPP satellite saw that Tropical Cyclone Winston maintained a pinhole eye as it tracked east of southern Vanuatu's islands in the Southern Pacific Ocean on Feb. 23. Infrared imagery showed bands of strong thunderstorms were wrapping into the low-level center of the storm.
On Feb. 23 at 0140 UTC (Feb. 22 at 8:40 p.m. EST) the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard NASA-NOAA's Suomi NPP satellite captured a visible image of Tropical Cyclone Winston that showed a pinhole eye as it was moving east of Vanuatu's southernmost islands.
Animated enhanced infrared satellite imagery indicated a slowly-decaying low-level circulation center with curved strong bands of thunderstorms wrapping into the center of the storm. The Atmospheric Infrared Sounder or AIRS instrument that flies aboard NASA's Aqua satellite provided infrared temperature data on the system on Feb. 23 at 01:53 UTC (Feb. 22 at 8:53 p.m. EST). Some cloud top temperatures were colder than minus 63 Fahrenheit/ minus 53 Celsius, indicating they were high into the troposphere. Cloud top temperatures that cold have shown that those storms can produce heavy rainfall
Joint Typhoon Warning Center (JTWC) said that at 1500 GMT (10 a.m. EST) Winston's maximum sustained winds dropped to 70 knots (80.5 mph/129.6 kph) making it a Category 1 hurricane. It was located about 303 nautical miles (348 miles/561.2 km) west-southwest of Suva, Fiji near 20.7 degrees south latitude and 173.8 degrees east longitude. Winston had increased in forward speed since Feb. 22 and was moving to the south-southeast to 9 knots (10.3 mph/16.6 kph).
JTWC forecasters expect that Winston will turn southwestward to west-southwestward on Feb. 24 as it transitions to the steering influence of a building sub-tropical ridge (elongated area of high pressure) to the south. Tc 11p is expected to weaken significantly after Feb. 24 as it encounters strong vertical wind shear and cooler sea surface temperatures.