Pacific ENSO Update

3rd Quarter, 2006 Vol. 12 No. 3

FSM Flag Federated States of Micronesia

Pohnpei State:During the 2nd Quarter of 2006, the rainfall throughout Pohnpei State was near normal on Pohnpei Island. Pingelap and at Mwoakilloa were drier than most locations on Pohnpei Island. Nukuoro and Kapingamarangi were wetter than normal. It has been wetter than normal on Kapingamarangi for a very long time (perhaps because of the effects of continually warmer than normal SST on the cloud systems in the area).

The 2nd Quarter rainfall total of 56.42 inches at Palikir was the highest reading in Pohnpei State, followed by 53.49 inches at Nukuoro. The 100.25 inches of rain at Nukuoro during the first 6 months of 2006 was one of the highest rain readings in all of Micronesia for that period.

Rainfall on top of Nahna Laud (the highest mountain in the interior rainforest of Pohnpei island) continued to be generally higher than at any other location. The rain gages at that site have been in operation for three years as a joint project between UOG and the Conservation Society of Pohnpei (CSP) sponsored by the U.S. Geological Survey. Twelve-month totals at the Nahna Laud site have reached as high as 331 inches.

Pohnpei Rainfall Summary 2nd Quarter 2006
Station   Apr. May Jun. Quarterly Total 1st Half Total
Pohnpei Island
Pohnpei WSO Rainfall (inches) 14.12 17.61 16.47 48.30 74.38
% of Normal 86% 92% 96% 92% 83%
Palikir* Rainfall (inches) 14.52 22.83 19.07 56.42 95.64
% of Normal 80% 108% 100% 96% 96%

Nahna Laud*

Rainfall (inches) 28.24 20.93 N/A N/A N/A
Atolls of Pohnpei State
Nukuoro Rainfall (inches) 23.35 15.04 15.10 53.49 100.25
% of Normal 156% 102% 124% 128% 129%
Pingelap Rainfall (inches) 7.02 13.01 12.82 32.85 67.93
% of Normal 41% 76% 79% 65% 76%
Mwokilloa* Rainfall (inches) 7.73 10.55 15.63 33.91 60.33
Kapingamarangi Rainfall (inches) 14.50 3.19 19.06 36.75 81.53
% of Normal 107% 31% 263% 118% 124%
* Long term normal is not established for these sites


Climate Outlook:

The risk of a damaging tropical storm or typhoon at any island in Pohnpei State is unlikely during 2006. The early stages of developing tropical cyclones may bring some episodes of heavy rain to Pohnpei for the remainder of the year, but these systems should not become tropical storms or typhoons until they move well away from Pohnpei.

Normal rainfall conditions is expected throughout Pohnpei State for the remainder of 2006. The rainfall at Kapingamarangi continues to exceed expectations. The three driest months on Kapingamarangi are typically August, September and October. Based on continually wet conditions there for the past two years, and a similar pattern of SST as during the past two years, the rainfall at Kapingamarangi may continue to be wet.

Predicted rainfall for Pohnpei State from July 2006 through Jun 2007 is as follows:

Inclusive Period

% of Long-Term Average
Pohnpei Islands and Atolls
 Kapingamarangi
Jul - Sep 2006 100% 110%
Oct - Dec 2006 100% 100%
Jan - Mar 2007 100% 100%
Apr - Jun 2007 110% 95% (?)
Source: UOG-WERI