As Tropical Cyclone Ula was coming together, NOAA's GOES-West satellite captured an image of the consolidating storm in the Southern Pacific Ocean.
NOAA's GOES-West satellite captured an image of the tropical low pressure areas designated as System 92P in the South Pacific Ocean on Dec. 29, 2015 at 2322 UTC (6:22 p.m. EST). The low pressure area continued to consolidate and organize and was designated Tropical Cyclone Ula on Dec. 30, 2015, at 0900 UTC (4 a.m. EST), east of American Samoa.
At that time, Ula's maximum sustained winds were near 45 knots (53.7 mph/83.3 kph). It was located near 12.0 degrees south latitude and 166.5 west longitude, about 282 nautical miles (324.5 miles/522.3 km) east-northeast of Pago Pago, American Samoa. Ula was moving to the south-southeast at 13 knots (14.9 mph/24.0 kph).
Animated multispectral satellite imagery shows a rapidly-consolidating, compact low-level circulation center with tightly-curved convective banding of thunderstorms wrapping into a central dense overcast. Microwave satellite data shows an eye in that central dense overcast.
Forecasters at the Joint Typhoon Warning Center expect Ula to curve to the southwest, remaining south of Pago Pago while intensifying to hurricane-force on Dec. 31, 2015.
By Jan. 2, 2016, Ula is expected to slow begin curving to the southwest as it approaches Fiji. Ula is expected to track along the western edge of a sub-tropical ridge (elongated area) of high pressure where it will encounter increasing vertical wind shear associated with a shortwave trough (elongated area of low pressure). For updated forecasts, visit the Joint Typhoon Warning Center website: http://www.usno.navy.mil/JTWC/ and Fiji's Meteorological Service: http://www.met.gov.fj/.