NASA sees Tropical Cyclone Gita weakening

IMAGE: On Feb. 16, GPM data showed that the heaviest precipitation, falling at rate of about 51 mm (2 inches) per hour, was shown west of Gita's eye.

Image credit: 
Credits: NASA/JAXA, Hal Pierce

NASA-NOAA's Suomi NPP satellite and the GPM core satellite passed over Tropical Cyclone Gita is it began weakening from vertical wind shear.

Warnings and watches are in effect for New Caledonia and Zealand is on alert for Tropical Cyclone Gita. In New Caledonia, the majority of the territory is on pre-alert with the exception of the Ile des Pins, which is on Alert #2. New Zealand is expected to be affected by Gita on February 19 and 20 and the meteorological service is tracking the storm.

The Global Precipitation Measurement mission or GPM core observatory satellite's Microwave Imager (GMI) instrument had a fairly good view of Tropical Cyclone Gita on February 16, 2018 at 0316 UTC (Feb. 15 at 10:16 a.m. EST). GPM's Dual Frequency Precipitation Radar (DPR) swath only covered the area west of GITA's main area of precipitation. The weakening tropical cyclone was passing the southeastern tip of New Caledonia. Although weakening, Gita still had winds estimated at over 90 knots (104 mph). Rainfall derived from GMI data showed that the heaviest precipitation, falling at rate of about 51 mm (2 inches) per hour, was shown west of Gita's eye. GPM is a joint mission between NASA and the Japan Aerospace Exploration Agency, JAXA.

On Feb. 16 at 0206 UTC (Feb. 15 at 9:06 p.m. EST) the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard NASA-NOAA's Suomi NPP satellite showed the eye of Gita southeast of New Caledonia. Some high level clouds have filled in the eye, but it was still quite visible in the VIIRS image.

On Feb. 16 at 10 a.m. EST (1500 UTC) Tropical Cyclone Gita's maximum sustained winds were near 92 mph (80 knots/148 kph). Gita was centered near 23.8 degrees south latitude and 167.6 east longitude, about 135 nautical miles southeast of Noumea, New Caledonia. Gita was moving to the west-southwest at 11.5 mph (10 knots/18.5 kph).

At that time, the Joint Typhoon Warning Center (JTWC) noted that "animated enhanced infrared satellite imagery shows a weakening tropical cyclone with a decaying convective structure, and vertical wind shear is pushing the thunderstorms away from the center of circulation.

Strong vertical wind shear are now sapping tropical cyclone Gita's strength. The JTWC predicts that the tropical cyclone will continue to weaken as Gita moves southwestward and encounters cooler ocean waters. Gita is expected to change course and move toward the southeast in a few days. A recent JTWC forecast indicates that Gita will transition to an extra-tropical low and move to a location between New Zealand's North and South Islands on February 20, 2018.

The Meteorological Service of New Zealand noted "Tropical Cyclone Gita continues to track southwards on Sunday and is likely to encounter an upper trough in the northern Tasman Sea. The system is likely to undergo extra-tropical transition on Sunday before tracking to the southeast towards New Zealand on Monday under the influence of the upper trough."

For updated warnings and watches in New Zealand, visit: http://www.metservice.com/warnings/tropical-cyclone-activity.

Credit: 
NASA/Goddard Space Flight Center