Pacific ENSO Update

4th Quarter, 2004 Vol. 10 No. 4

American Samoa:  This year’s dry season in American Samoa was abnormally dry. During every month since April 2004 (except for July), it has been drier than normal. Rainfall at Pago Pago Airport for July, August, and September was 7.11 inches (113%), 2.67 inches (40%), and 4.95 inches (74%), respectively, amounting to 75% of normal for the 3-month period. Total rainfall during the months of May through September at Pago Pago Airport (typically the driest months) was 23.60 inches or 63% of the normal for the period. During October, near normal rainfall was experienced at American Samoa. The threat of a tropical cyclone in American Samoa for the upcoming tropical cyclone season that begins there in December 2004 may be slightly higher than normal.

Computer forecasts and a consensus of outlooks from several regional meteorological centers indicate that rainfall in American Samoa is likely to be near normal for the remainder of the year (the onset of the next rainy season). Thereafter, there is some indication that conditions may be dryer than normal. Long-range computer rainfall forecasts, however, have only limited skill in the tropical Pacific islands.

Predicted rainfall for American Samoa from November 2004 through October 2005 is:

Inclusive Period % of Long-Term Average
Nov - Dec 2004 (Start of Rainy Season)
90%
Jan - Apr 2005 (Heart of Rainy Season)
95%
May - Oct 2005 (Next Dry Season)
90%

source: UOG-WERI