Federated States of Micronesia

Chuuk State:  Rainfall in Chuuk State during the first half of 2010 had a large north-south gradient reflecting the placement of the trade-wind trough across the southern portions of the state. The northern atolls received the least amount of rain, and some of the atolls further south in the Mortlocks received the most. The 67.54 inches observed at Ettal Atoll in the southern Mortlocks was the highest observed 2010 First Half total throughout Chuuk State. The 34.97 inches and 25.22 inches observed at Fananu and Piis Panew, respectively, were among the lowest readings during the first half of 2010. The 49.61 inches recorded at the Chuuk WSO during the first half of 2010 was well below normal (81%).

Chuuk State Rainfall Summary 2nd Quarter and 1st Half 2010

Climate Outlook: Easterly low-level winds should continue to dominate the flow throughout Chuuk State for the next three months, with a below average number of days with west or southwest winds. The weather patterns during the remainder of 2010 are anticipated to be analogous to the atmospheric weather patterns seen during 2008 when easterly winds and tranquil weather persisted for the whole year. Rainfall should be near normal. Beginning in August and continuing through December, a few of the tropical cyclones of the western North Pacific basin will begin their lives in Chuuk State as depressions. One or two occurrences of gale-force winds associated with a developing tropical cyclone may affect Chuuk Lagoon or atolls to the north, especially in the fall of 2010. This represents a near normal risk of hazardous effects from tropical cyclones.

Because of the easterly wind anomalies expected to dominate the low-level wind pattern across Micronesia and the equatorial Pacific, the sea level should continue to rise, and sea-level anomalies should approach or exceed those seen in the region during 2008. Higher-than-normal sea level will expose the atolls of Chuuk State to a heightened risk of sea inundation, especially towards the end of the year (late November and December 2010). At this time of the year, the extra-tropical low pressure systems that move eastward from Japan may produce large northerly swells that will move south from their North Pacific origin and pass through Chuuk State causing coastal sea inundations from large waves on some atolls where similar conditions caused sea inundation in December 2008.

Predictions for Chuuk State from July 2010 through June 2011 are as follows:

Forecast rainfall quantities represent BEST ESTIMATES given the probabalistic forecast for each particular season and station.

source: UOG-WERI