Federated States of Micronesia

Yap State: 2007 annual rainfall totals at all Yap Island locations were generally in the range of 130 to 140 inches, which is approximately 10 to 20 inches above the typical value for a calendar year. Throughout much of the past year, many of the disturbances that became the tropical cyclones of the western North Pacific passed north of Yap, contributing to the abundant rainfall. The weather on Yap Island was otherwise uneventful, with no reports of unusually heavy rain or high winds. To the south, Woleai was quite dry, with a 2007 annual rainfall total of 96.54 inches (69% of normal). The shift of tropical cyclone activity to the north of Yap may account for the lack of rain at Woleai during the final quarter of 2007. At Ulithi, the 2007 rainfall was above normal by the same magnitude as on Yap Island. The total of 145.26 inches at Dugor on Yap Island was the highest recorded value for all of Yap State for the calendar year of 2007.

Yap State Rainfall Summary 4th Quarter 2007

Climate Outlook: All of the islands of Yap State should have abundant rainfall for the next three months, and will probably remain wet for most months of the coming year. La Niña is at its peak now and will wane during 2008. Past years with similar ENSO conditions have brought above-average rains to Yap State. Woleai should be wet until the monsoon trough pulls well to its north in August through October, and this may result in a period of relative dryness there as was seen during 2007.

Stronger than normal trade winds and sub-surface ocean heating in the western North Pacific will continue to keep sea levels above normal. Tropical cyclone activity in the western North Pacific is expected to be higher than it was during the quiet 2007. During August through December 2008, 2 or 3 typhoons should pass to the north of Yap Island and Ulithi producing gusty westerly winds and hazardous seas in the island waters. The odds of damaging winds from a tropical cyclone on Yap or any of its northern atolls will be approximately 10 to 15% for the calendar year 2008, which represents a slightly elevated risk.

Predicted rainfall for Yap State from February 2008 through January 2009 is as follows:

source: UOG-WERI