Status Report

Late-season Central Pacific tropical depression forms

By SpaceRef Editor
December 31, 2015
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Tropical Depression 9C formed in the Central Pacific, 30 days after the official end to the Central Pacific Hurricane Season. An image from NOAA’s GOES-West satellite revealed the late-season tropical depression was still struggling to organize.

Tropical Depression 9C (TD9C) formed at 0300 UTC on Dec. 31 (10 p.m. EST on Dec. 30) in the Central Pacific, just north of the Equator and far to the southwest of the Johnston Atoll.

NOAA’s Central Pacific Hurricane Center (CPHC) said that TD9C is the sixteenth tropical system of the year to either form within or pass through the central north pacific basin.

An image from NOAA’s GOES-West satellite on Dec. 31 at 1200 UTC (7 a.m. EST) showed that newly formed Tropical Depression 9C appeared elongated. Tropical cyclones strengthen as their structure becomes more circular. An elongated system is a weaker system. The image was created by the NASA/NOAA GOES Project at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

NOAA’s Central Pacific Hurricane Center (CPHC) noted that TD9C’s structure continues to suggest an elongated east to west oriented system. That indicates there likely is still a low-level trough-like (elongated area of low pressure) feature associated with the depression. The CPHC discussion on Dec. 31 said that the trough-like feature is “not unexpected when examining the unusual belt of strong westerly winds south of the equator…as well as the extensive area of 30 knot easterly winds to the north of TD9C.”

By 0900 UTC (4 a.m. EST) on Dec. 31, the center of TD9C was located near latitude 2.5 degrees north and longitude 175.8 degrees west. That’s about 1,070 miles (1,720 km) south-southwest of Johnston Island and about 1,770 miles (2,850 km) southwest of Honolulu Hawaii. TD9C was moving toward the northwest near 3 mph (6 kph) and that general motion is expected to continue through Friday, Jan. 1. The estimated minimum central pressure is 1001 millibars.

Maximum sustained winds are near 35 mph (55 kph) with higher gusts. Little change in intensity is expected during the next couple of days, because of strong easterly vertical wind shear in the area as shown by data from ships. NOAA’s Central Pacific Hurricane Center noted that if TD9C avoids dissipation, it could reach tropical storm strength by Monday, January 4, 2016 as it crosses the International Date Line and moves into the Northwestern Pacific Ocean basin.

TD9C is not near any land areas, so no watches are warnings are in effect. For updated forecasts, visit:

SpaceRef staff editor.