Pacific ENSO Update
1st Quarter, 2005 Vol. 11 No. 1
American Samoa: The total rainfall of 95.76 inches in American Samoa during the calendar year of 2004 was below normal (79%). In both total annual rainfall and percent of normal annual rainfall, American Samoa was one of the driest locations covered in this summary (Fig. 1a, 1b). Only four of twelve months (February, March, July and October) during 2004 had above normal rainfall. Rainfall at Pago Pago Airport for October, November, and December was 11.52 inches (107%), 4.00 inches (37%), and 9.68 inches (67%), respectively, amounting to 70% of normal for the 3-month period. With warmer than normal sea surface temperatures persisting in the central equatorial Pacific, the threat of a tropical cyclone in American Samoa may be slightly higher than normal through April 2005 (at print time Tropical Cyclone Nancy and Olaf are passing through the region. Information on the effects of these typhoons will be included in the next Pacific ENSO Update).
Computer forecasts and a consensus of outlooks from several regional meteorological centers indicate that rainfall in American Samoa is likely to be below normal through the rest of the current rainy season and through the next dry season. Long-range computer rainfall forecasts, however, have only limited skill in the tropical Pacific islands.
Predicted rainfall for American Samoa from February 2005 through January 2006 is:
| Inclusive Period | % of Long-Term Average |
|---|---|
| Feb-Apr 2005 (Heart of Rainy Season) | 80% |
| May-Oct 2005 (Next Dry Season) | 90% |
| Nov 2005-Jan 2006 (Onset of Next Rainy Season) | 95% |
source: UOG-WERI