Republic of the Marshall Islands: Until recently, the RMI has been drier than normal. In fact, the long-term time series of rainfall at Kwajalein and at Majuro (which extend back into the 1950’s) show a statistically significant trend of decreasing rainfall at both islands. With this as a background, the recent wet conditions in the RMI are all the more unusual. During the first three months of the year, the RMI enters its normal dry season. During the 1st Quarter of 2011, there was as much rain in each of the dry season months as in a wet month of the rainy season. At Kwajalein, the 3-month total of 31.34 inches was 240% of normal, and the 36.98 inches of rainfall at Majuro was 162% of the normal 1st quarter rainfall. Unusual deep convection was continually noted, with unusual occurrences of lightning. A large portion of the high monthly rainfall in the RMI came in extreme 24-hour events of 2 or more inches. During April, the wet pattern seemed to break, and dry trade winds prevailed.

Republic of the Marshall Islands Rainfall Summary 1st Quarter 2011

Climate Outlook: The rainy season in the RMI slowly builds from April through June, then extends through the final quarter of the year. Abundant rainfall should continue in the RMI for the foreseeable future, but perhaps not so far above normal as during the past several months. Computer forecasts and the typical behavior of the climate when La Niña fades suggest that 2011 will have at least near normal rainfall. Since the cause of the long-term decline of rainfall in the RMI is not known, we can not know how to factor this trend into future rainfall forecasts.

Predicted rainfall for the RMI from April 2011 through March 2012 is as follows:

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

source: UOG-WERI