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The 1974 Central Pacific Tropical Cyclone Season


Tropical Depression #11 formed in the ITCZ on the 6th and drifted westward to 9.7·N 140.OW at 09/0000Z. After entering the CPHC area of advisory responsibility it briefly headed for the Hawaiian Islands but never reached storm strength and at 13.6N 147.9W at 11/0000Z was downgraded to a disturbance with only 20-knot winds and no significant associated weather. The vortical remnant was followed another 12 hours to 14.ON 152.1W at which point it was no longer recognizable.


Satellite pictures during the morning of the 17th showed increased activity on the ITCZ near 12N 114W. By the end of the day a disturbance was identified and tracked westward at 16 knots. The westward speed slowed to about 10 knots as development took place, reaching tropical storm intensity near 14N 128W at 20/1800Z.

Named tropical storm IONE, with 35-knot winds, the system curved a little southwestward and weakened to a tropical depression on the morning of the 22nd and then continued west to near 12.5N 138.5W at 23/1800Z. Morning visual satellite imagery showed considerable intensification had taken place during the night and the depression was raised to hurricane classification with 65-knot winds.

IONE continued intensifying, with 100-knot winds by 24/0000Z, as it moved into the Honolulu area of responsibility near 13N 140W . The hurricane had been moving west- northwest at 10 knots with winds of 80-100 knots but then began to curve sharply and move slowly northward at 6-7 knots. By 26/1200Z IONE was centered near 17N 144W. It then slowly moved a little east of north, and weakened rapidly on the 27th; from a hurricane with 70- knot winds at 1200Z to a tropical storm with 50-knot winds at 1800Z and to a depression with 30-knot winds at 29/0600Z.

During this weakening period, IONE's track resembled a large inverted U, reaching its highest latitude at 19 . 5 N on the 27th before swinging southwestward. After being downgraded to a depression at the bottom of its southwestward track at 11.3N 146.7W, OLIVE drifted westward before ending its career on the 30th, 170 nautical miles south-southeast of South Point, Hawaii.


Infra-red satellite imagery early on the 21st indicated a tropical disturbance had formed in the ITCZ near 11N 147W. it drifted slowly northwest and intensified to depression stage during the next 24 hours. Visual imagery during the morning of the 22nd dictated the CPHC at Honolulu to issue the first advisory on the system, positioning it at 12.9N 149.6W with maximum sustained winds of 25 knots at 22/1800Z.

Moving west-northwestward at about 10 knots the system intensified to minimal tropical storm strength at 13.5N 152.9W at 23/1200Z. Early on the 23rd maximum sustained winds reached 40 knots while gales extended out 75 miles in all directions. However, before the day Was through OLIVE had dropped back to a depression near 14N 156W. The system maintained depression status for another 30 hours 0 before being downgraded to a disturbance at 14.5N 163.1W at 25/1200Z. The vortical remnants were recognizable on satellite imagery till 26/0600Z at 14.3N 16.8W, approximately 210 miles southeast of Johnston Island.