Pacific ENSO Update

4th Quarter, 2008 Vol. 14 No. 4

FSM Flag Federated States of Micronesia

Yap State: The same monthly pattern of rainfall seen at Guam and in the CNMI (a dry July and August followed by a wet September) was note at all Yap Island locations and at Ulithi. Tropical disturbances passing through the region caused some widespread heavier rainfall events during September, yet it was not enough to overcome the dry conditions of July and August. The 3rd Quarter of 2008 yielded below normal rainfall totals at all Yap State sites. The WSO on Yap Island was the only location in Micronesia (other than the four Kosrae sites) to have a monthly rainfall value in excess of 20 inches during any month of the 3rd Quarter. This is direct evidence of the very tranquil weather conditions that have persisted in the region for more than two years.

Yap State Rainfall Summary 3rd Quarter 2008

Station   July August Sept. 3rd Qtr
Predicted
Yap Island
Yap WSO
 Rainfall (inches)
6.93
9.69
5.23
21.85
37.61
% of Normal
124%
119%
39%
80%
83%
Dugor*
 Rainfall (inches)
5.76
14.47
3.37
23.60
36.36
% of Normal
103%
178%
25%
86%
78%
Gilman*
 Rainfall (inches)
4.94
10.66
5.71
21.31
37.41
% of Normal
89%
131%
42%
77%
80%
Luweech*
 Rainfall (inches)
6.13
7.21
5.00
18.34
33.92
% of Normal
110%
88%
37%
67%
73%
Maap*
 Rainfall (inches)
8.36
11.11
3.69
23.16
38.61
% of Normal
150%
136%
27%
84%
83%
North Fanif*
Rainfall (inches)
6.96
12.13
5.65
24.74
36.83
% of Normal
125%
149%
42%
90%
79%
Rumung*
 Rainfall (inches)
6.33
12.10
7.12
25.55
37.04
% of Normal
113%
148%
53%
93%
79%
Tamil*
 Rainfall (inches)
7.18
10.19
5.45
22.82
35.98
% of Normal
129%
125%
40%
83%
77%
Outer Islands
Ulithi
 Rainfall (inches)
4.41
9.20
6.84
20.45
31.20
% of Normal
90%
119%
63%
87%
78%
Woleai
 Rainfall (inches)
6.52
5.76
4.04
16.32
28.58
% of Normal
59%
47%
31%
45%
46%
Predictions made in 2nd Quarter 2008 Pacifc ENSO Update newsletter.
* Long term normal is not established for these sites.

Climate Outlook: There is a slight risk of a damaging tropical cyclone in Yap State or its northern atolls in November or December of 2008; about the only place in Micronesia where there will be any tangible risk of gales (or stronger) from a tropical cyclone. The level of threat (5% chance) of damaging winds from a tropical storm or typhoon at Yap Island and at Ulithi, however, is relatively low. The threat is even less to the southeast at Woleai.

Predicted rainfall for Yap State from October 2008 through September 2009 is as follows:

Inclusive Period
% of Long-Term Average Rainfall /
Forecast Rainfall (inches)
Yap and Ulithi
Woleai

October - December 2008
(End of Rainy Season)

110%
(33.45 inches)
90%
(36.21 inches)

January - April 2009
(Next Dry Season)

100% 100%

May - June 2009
(Onset of Next Rainy Season)

120% 90%

July - September 2009
(Heart of Next Rainy Season)

100% 100%
Forecast rainfall quantities represent BEST ESTIMATES given the probabalistic forecast for each particular season and station.

source: UOG-WERI