Federated States of Micronesia

Pohnpei State: Rainfall in Pohnpei State during the third quarter of 2004 was drier than normal at most observing sites (Pohnpei Island, Nukuoro, and Pingelap were dry; Kapingamarangi was wet). With the SST distribution shifting to a pattern consistent with El Niño (warmer-than-normal SST along the equator from Kapingamarangi eastward to the Galapagos Islands in the eastern Pacific), the rainfall distribution has also trended toward a pattern consistent with El Niño (drier than normal in the northern and western islands of Micronesia, and wet at islands near the equator — such as Kapingamarangi and Tarawa). The rainfall at the Pohnpei WSO (on the north side of Pohnpei Island) was 11.87 inches (66%) in July, 17.34 inches (105%) in August, and 12.57 inches (78%) in September, and 11.26 inches in October. For the 5-month period June through October, the 74.10 inches at the WSO was 99% of normal.

At Pingelap, observed rainfall in June, July, August, September, and October was 16.58 inches (102%), 12.04 inches (76%), 15.06 inches (101%), 9.31 inches (62%), and 7.02 inches (47%), respectively, for a 5-month total of 60.01 inches (78)%. At Nukuoro, observed rainfall in June, July, August, September, and October was 12.76 inches (105%), 6.42 inches (45%), 11.51 inches (101%), 13.65 inches (120%), and 4.89 inches (45%) respectively, for a 5-month total of 49.23 inches (82%). The rainfall at Kapingamarangi during June, July, August, September, and October was 20.17 inches (278%), 6.75 inches (65%), 15.82 inches (257%), 10.74 inches (182%), and 3.42 inches (71%) respectively. For the 5-month period June through October, the 62.65 inches at Kapingamarangi was 181% of normal. June through October are normally the driest months at Kapingamarangi, but persistent convection has been anchored along the equator in association with warmer than normal SST there. This convection has been producing substantial amounts of rain at Kanpingamarangi, which is located near the equator.

In cooperation with the Conservation Society of Pohnpei (CSP), and with help from the Nature Conservancy and the local office of the National Weather Service, researchers from the University of Guam have set up a network of rain gages in Pohnpei. This network of electronic and manual rain gages extends from coastal locations to the highest mountain peak (Nahna Laud) in the center of the island. During June, July, August, September, and October, the rain gage on top of Nahna Laud recorded 34.15 inches, 16.98 inches, 30.40 inches, 20.28 inches and 22.53 inches, respectively. The 5-month total of 124.34 inches was the highest recorded at any location in Micronesia! (Fig. 2a and 2b).

El Niño conditions bring an enhanced threat of a tropical cyclone to the eastern Caroline Islands. It is possible, during the next 3 months (November, December 2004, and January 2005) for a tropical storm to pass to the north of Kosrae bringing a period of heavy rains, gusty southwest winds, and high surf. Kosrae, fortunately is located close enough to the equator so that a direct strike by a strong tropical storm or a typhoon is very unlikely.

Predicted rainfall for Pohnpei State from Nov 2004 through Oct 2005 is as follows: