Pacific ENSO Update

2nd Quarter, 2007 Vol. 13 No. 2

American Samoa:  The 1st quarter of 2007 started off with wet conditions across American Samoa. Above-normal rainfall totals were recorded at Pago Pago International Airport, which received 51.67 inches of rain for the quarter (138.5% of normal). Likewise, Aasufou recorded 80.09 inches (149.9% of normal) for the three month period. The most rainfall received for both stations during this quarter occurred in January, when WSO Pago Pago received 21.01 inches (149.9% of normal) and Aasufou received 36.76 inches of rainfall (198.5% of normal).

— WSO Pago Pago

American Samoa Rainfall Summary 1st Quarter 2007
Station   Jan. Feb. Mar. 1st Qtr Predicted
Pago Pago WSO
Rainfall (inches) 21.01 10.35 20.31 51.67 43.93
% of Normal 150% 85% 182% 138% 120%
Aasufou
Rainfall (inches) 36.76 17.58 27.56 80.09 64.11
% of Normal 199% 98% 142% 150% 120%
Predicted rainfall refers to forecast made in 4th Quarter 2006 PEAC Newsletter.

Climate Outlook: American Samoa has passed through the heart of its rainy season, and is now entering the onset of the next dry season (May to June 2007). It has been very wet in American Samoa for many months. However, with sea surface temperatures cooling and forecasts favoring weak La Niña conditions to develop, American Samoa will likely experience near normal to below normal rainfall through June and slightly below normal rainfall through the heart of the 2007 dry season. As of the 24 th of April, the Pago Pago Weather Service Office has only recorded 3.19 inches of rainfall for the month (28.6% of normal).

The threat of a damaging tropical cyclone in any of the islands of American Samoa is nearly over for this season. It was anticipated that the cyclone threat for American Samoa (and the South Pacific in general) was going to be higher than average because of El Niño. In fact, the cyclone numbers were below average for the South Pacific, and there is only a very small chance for another hurricane to affect the region during the next two months.

Predicted rainfall for American Samoa from May 2007 through April 2008 is as follows:

Inclusive Period
% of Long-Term Average Rainfall
May - Jun 2007 (Onset of Next Dry Season)
90%
Jul – Sep 2007 (Heart of Next Dry Season)
85%
Oct 2007 – Jan 2008 (Onset of Next Rainy Season)
95%
Feb – Apr 2008 (Heart of Next Rainy Season)
100%

source: UOG-WERI