Pacific ENSO Update

2nd Quarter, 2007 Vol. 13 No. 2

FSM Flag Federated States of Micronesia

Pohnpei State: First quarter rainfall throughout Pohnpei State was near normal at most locations, with a few atolls (most notably Mwoakilloa and Nukuoro) experiencing very wet conditions. An extreme daily rainfall event at Mwoakilloa at the end of February associated with a tropical disturbance passing through Pohnpei State brought the February monthly total to 25.97 inches (the highest monthly total at any recording location in all of the state during the first three months of 2007). For most of January it was quite dry on Pohnpei Island and on some atolls. It was so hot and dry on Pohnpei Island during January (with only 4.90 inches of rain at the Pohnpei WSO in Kolonia) that residents began to worry about the water supply and stream flow. Luckily, rains returned in February, and fears of drought were eased. Kapingamarangi was wet once again, and has been for many months. The tropical depression that became Typhoon Kong-Rey passed just to the southwest of Pohnpei Island in late March. This scenario was typical for this time of year, and does not indicate an increased risk of a typhoon or tropical storm for Pohnpei in the year ahead.  

Pohnpei Rainfall Summary 1st Quarter 2007

Station   Jan. Feb. Mar. 1st Qtr Predicted
Pohnpei WSO Rainfall (inches) 4.90 19.50 16.14 40.54 29.92
% of Normal 39% 199% 116% 112% 80%
Palikir Rainfall (inches) 8.54 10.11 16.50 35.15 32.44
% of Normal 60% 87% 114% 87% 80%
Kolonia Airport Rainfall (inches) 3.93 17.31 16.26 37.50 25.80
% of Normal 35% 186% 140% 117% 80%
Nukuoro Rainfall (inches) 22.64 14.97 12.71 50.32 28.12
% of Normal 193% 142% 93% 140% 80%
Pingelap Rainfall (inches) 9.76 8.66 13.87 32.29 31.24
% of Normal 79% 71% 96% 83% 80%
Mwokilloa* Rainfall (inches) 5.24 25.97 13.53 44.74 30.04
Kapingamarangi Rainfall (inches) 9.03 18.41 13.04 40.48 34.60
% of Normal 86% 179% 94% 117% 100%
Predicted rainfall refers to forecast made in 4th Quarter 2006 PEAC Newsletter.
* Long term normal is not established for these sites


Climate Outlook: Rainfall throughout Pohnpei State should be near normal for the foreseeable future. The rainfall at Kapingamarangi could drop below normal for the first time in many months if La Niña conditions develop during the summer. No typhoons or tropical storms are anticipated this year in Pohnpei State . Several tropical disturbances should begin near Pohnpei State and move away to the west to become tropical cyclones affecting Guam, Yap , or the CNMI. This pattern is normal, and was seen with the development of Typhoon Kong-Rey.

Predicted rainfall for Pohnpei State from May 2007 through April 2008 is as follows:

Inclusive Period

% of Long-Term Average Rainfall
Pohnpei Islands and Atolls Kapingamarangi
May - Jun 2007
100% 100%
Jul - Oct 2007
100% 95%
Nov 2007 - Jan 2008
100% 95%
Feb - April 2008
110% 90%

Source: UOG-WERI