Federated States of Micronesia

Yap State:  Rainfall throughout Yap State during 2006 was close to normal. The first half of 2006 was somewhat dry, but monthly rainfall in excess of 15 inches was experienced at many locations in during the 4th quarter. Much of the heavy rainfall in these months was from passing tropical disturbances and developing tropical cyclones, some of which went on to become devastating typhoons in the Philippines. Only one tropical cyclone adversely affected Yap during 2006. During the morning of the July 1, Tropical Storm Ewiniar (TC04W) passed approximately 40 miles to the southwest of Yap. This severe tropical storm caused a surprising amount of damage on Yap Island from sea inundation. The highest waves during the storm came at high tide, and there was substantial inundation that flooded coastal roads and damaged some homes. Sea inundation levels were approximately half of those generated by Typhoon Sudal. A boat at mooring broke loose and damaged the official tide gage in Colonia.

In an atypical pattern, Ulithi received a higher 2006 annual total of rainfall than at the Yap WSO, which, in turn, received more rainfall than Woleai. This appears to be an artifact of several developing tropical cyclones that passed to the north of Yap Island and produced heavy rainfall at Ulithi and on Yap Island , with lesser amounts to the south. Most reporting sites on Yap Island and on Ulithi received between 25 to 35 inches of rain during the 4th Quarter, and between 115 to 125 inches for the entire year.

Yap State Rainfall Summary 4th Quarter 2006

Climate Outlook: Below normal rainfall is anticipated throughout all of Yap State for the first six months of 2007. Island residents are urged to participate in voluntary water conservation measures, and to undertake low-cost repairs and maintenance of the means of obtaining drinking water. If extreme dry conditions develop in the next 3 to 6 months, then a more serious effort may be required to ensure adequate water supplies for all islanders. The magnitude of the dry conditions expected for the next 6 months is not anticipated to be as extreme as the dry conditions experienced in the first 6 months of 1983, 1992, or 1998. Most locations are expected to receive 60% to 70% of the rainfall normally expected during the first six months of 2007. However, month-to-month variations in rainfall patterns (which are unpredictable) may cause any location to experience less than half of normal rainfall during any one or two of the months from January through June of 2007. As on Guam, Yap Island is prone to wildfires during very dry conditions, and residents may wish to clear away brush and combustible materials from areas they wish to protect from fire. At this time, the dry conditions are not expected to be as bad as those experienced during 1998.

Predicted rainfall for Yap State from February 2007 through January 2008 is as follows:

source: UOG-WERI