Pacific ENSO Update

3rd Quarter, 2007 Vol. 13 No. 3

FSM Flag Federated States of Micronesia

Chuuk State: Rainfall amounts during the first half of 2007 varied substantially across Chuuk State: dry in the north (e.g., Fanan Ounoun and Piis Panew) and wet in the south (e.g., Ettal, Lukunoch and Ta). It was very dry throughout much of Chuuk State early in the year (January through March), and wetter thereafter. Effects of drought and substantial sea inundation on some of the northern atolls earlier in the year is still causing some problems, particularly the salt-induced withering of taro patches and other staple food plants such as breadfruit trees. The 61.88 inches of rainfall during the first half of 2007 at the WSO on Weno Island was 101% of normal, and was one of the higher values of rainfall in Chuuk State for this period. Only Ta, with a six month total of 76.97 inches, received more rain than the amount recorded at the WSO.

Chuuk State Rainfall Summary 2nd Quarter 2007

Station   Apr. May June 2nd Qtr Predicted (2nd Qtr) 1st Half 2007
Chuuk WSO Rainfall (inches)
8.79
10.98
15.92
35.69
34.60
61.88
% of Normal
71%
90%
136%
98 %
95%
101%

Piis Panew*

Rainfall (inches)
7.39
8.85
4.98
21.22
34.60
30.52
Xavier HS Rainfall (inches)
12.47
7.26
14.53
34.26
34.60
54.61

Lukunoch*

 Rainfall (inches)

9.98

5.40
12.42
27.80
34.49
60.43
Ettal* Rainfall (inches)
10.28
9.76
3.14
23.18
34.49
59.51

Ta*

Rainfall (inches)
11.23
14.57
10.86
36.66
34.49
76.97

Fananu*

Rainfall (inches)
9.04
12.04
9.56
30.64
32.78
46.56
Onoun* Rainfall (inches)
6.17
11.75
10.90
28.82
32.78
46.06

Losap*

Rainfall (inches)
8.71
10.55
9.82
29.08
34.60
52.21

Nama*

Rainfall (inches)
10.87
11.86
11.31
34.04
34.60
60.69

Polowat

Rainfall (inches)
8.89
10.39
7.01
26.29
26.13
56.61
Predicted rainfall refers to forecast made in 1st Quarter 2007 PEAC Newsletter.
* Long term normal is not established for these sites
** Estimated

Climate Outlook: Easterly trade winds should continue to dominate the flow in eastern Micronesia (Pohnpei and eastward), and keep rainfall average to slightly below average there. Monsoon and storm activity will have more influence in western Micronesia (Chuuk and westward, including all islands of Chuuk State), where the rainfall should be near normal with substantial month-to-month variations. Beginning in August and continuing through December, several of the tropical cyclones of the western North Pacific basin will begin their lives in Chuuk State as depressions. These depressions will bring episodes of heavy showers across Chuuk State before they move northwestward and become named cyclones somewhere beyond Guam on their journey to Philippine or East Asian waters. No damaging wind from any tropical cyclone is anticipated anywhere in Chuuk State until late in the year (October through December), when any one of these depressions may become a tropical storm within the boundaries of Chuuk State.

Forecast rainfall for Chuuk State from August 2007 through July 2008 is as follows:

Inclusive Period
% of Long-Term Average Rainfall /
Forecast Rainfall (inches)
Chuuk Lagoon, and Northern Mortlocks
Polowat
Northern Atolls

Southern
Mortlocks
Aug - Oct 2007
100%
(38.08 inches)
100%
(40.25 inches)
100%
(38.08 inches)
100%
(39.52 inches)
Nov 2007 - Jan 2008
110%
110%
100%
100%
Feb - Apr 2008
100%
100%
90%
100%
May - July 2008
110%
100%
100%
100%
Forecast rainfall quantities represent BEST ESTIMATES given the probabalistic forecast for each particular season and station.

source: UOG-WERI