CURRENT CONDITIONS

Many of the islands of Micronesia typically enter their dry season at the start of the calendar year; and on some islands (especially those north of 10º N), the dry season persists until June or July. On islands located further to the south, abundant rains occur throughout the entire year. The rainfall distribution in Micronesia during the first three months of 2006 was characterized by a sharp north-south gradient (north dry, south wet) superimposed on a gradual east-west gradient (east dry, west wet) related to La Niña circulation anomalies and an active Australian Northwest Monsoon. There was abundant rainfall south of roughly 7ºN (for example, Kosrae), and very dry conditions at some islands located to the north of 8ºN (for example, the northern Marshall Islands) (Fig. 1a, 1b). The first quarter rainfall totals were generally highest in the southernmost islands of each State. Yap State was drier than normal except at Woleai, which is furthest south. Chuuk State was generally drier than normal except in some of the Mortlocks, which are further south. In Pohnpei State, locations furthest north (such as some of the sites on Pohnpei Island) were moderately dry, whereas islands further to the south (such as Nukuoro and Kapingamarangi) were wetter. Kosrae and the Republic of Palau had abundant rains. Guam and the CNMI started off wet in January and February then were very dry in March and April. Rainfall in American Samoa was phenomenal during February when a vigorous northwest monsoon persisted in the area, and some tropical cyclones passed nearby as they moved southeastward along the axis of the monsoon trough. When the northwest monsoon retreated westward in March, the rainfall in Samoa was much lower, and tropical cyclone activity shifted westward into the Coral Sea and the top end of Australia. First quarter rainfall totals were less than 80% of normal at some locations within Chuuk State, the northern RMI, and on Guam. First quarter rainfall totals in excess of 120% of normal occurred in some of the southernmost islands of Chuuk State, Pohnpei State, and the RMI; and exceeded 120% of normal throughout Palau and American Samoa. The highest First Quarter rainfall total recorded in Micronesia was the 62.20 inches at Utwa on Kosrae; Nukuoro and the Palau International Airport followed next with 46.76 inches and 46.58 inches, respectively. The lowest recorded First Quarter rainfall total in Micronesia was the 7.12 inches at Wotje in the northern RMI, where all reporting locations indicated less than 10 inches for the 3-month period.

Dry conditions are anticipated to continue throughout much of Micronesia in the northernmost locations that were dry in the First Quarter. The trade wind trough has been re-established over southern Micronesia, and rainfall should be abundant in most areas south of 8ºN by the end of April, for areas south of 10ºN by the end of May, and for the Mariana Islands by the end of July. Residents in the northern Marshall Islands are encouraged to conserve water until the rains return. For most of Micronesia, the dry season has ended, but for some locations, the wet season has not yet begun. These areas ( Yap, CNMI, Guam and northern RMI) are in the transition to the wet season. Rainfall in American Samoa should remain near normal now that the Northwest Monsoon is over and the South Pacific Convergence Zone has moved away from the islands.

Most of the statistical and coupled model forecasts indicate ENSO neutral conditions in the tropical Pacific through the end of 2006. The spread of the most recent statistical and coupled model forecasts (weak La Niña to weak El Niño) indicates uncertainty in the outlooks for the last half of the year. Current conditions (stronger-than-average easterly winds over the central equatorial Pacific and slightly cooler Eastern Pacific sea surface temperatures) indicate that there are some residual weak La Nina conditions lingering, however most of the statistical and coupled models show this trend weakening further and predict ENSO neutral for the next 3-6 months; The synopsis from the CPC EL NIÑO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC DISCUSSION posted on the U.S. Climate Prediction Center web site on May 11, 2006 was for “ENSO-neutral conditions are expected to prevail during the next 3-6 months” .