Pacific ENSO Update
2nd Quarter, 2005 Vol. 11 No. 2
Extreme month-to-month variation in rainfall marked the first three months of 2005. At most recording locations, February’s rainfall was very low; as low as one inch in several locations in Chuuk State and the Republic of Palau. A special abbreviated supplement to the ENSO Newsletter was issued to address islander’s concerns that the very dry February would lead to a more sustained drought. Forecasters at PEAC felt that February’s very low rainfall was an extreme short-term event that would abate in subsequent months. Throughout Micronesia, one month of very low rainfall is sufficient to cause substantial draw-down of stream flow on high islands (such as Pohnpei), problematic losses to rain catchments and other sources of surface water, stress to local crops, and wildfires on islands with large tracts of grasslands (such as Guam). In March and April 2005, rains returned in abundance to many islands, alleviating concerns of a prolonged drought.
For the first quarter of 2004, most of the islands of Micronesia and American Samoa had near normal to above normal rainfall (Fig. 1a, 1b). Only the northernmost islands, such as the CNMI and Kwajalein, experienced persistent dryness that was considerably less than normal for this period.
Near normal rainfall is anticipated throughout much of Micronesia and American Samoa for the next 3 to 6 months; however, large month-to-month variability is expected.
The general consensus among international computer climate forecasts is for a continued slide away from weak El Niño conditions back toward ENSO Neutral conditions during mid-2005. For more information, see the CPC EL NIŅO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC DISCUSSION for May.