Pacific ENSO Update

2nd Quarter, 2006 Vol. 12 No. 2

FSM Flag Federated States of Micronesia

Yap State:  The total 1st Quarter 2006 rainfall at the WSO on Yap Island was below normal at 12.36 inches (64%). All other recording locations on Yap Island were wetter than at the WSO, with 1st Quarter rainfall totals generally between 15 to 20 inches. The highest 1st Quarter rainfall recorded on Yap Island was the 19.89 inches (103%) measured at Tamil. In all of Yap State, the highest 1st Quarter rainfall total of 29.43 inches (111%) was recorded at Woleai, which (at its more southern location) is normally wetter.

Yap State Rainfall Summary 1st Quarter 2006
Station   Jan. Feb. Mar. Total
Yap Island
Yap WSO Rainfall (inches) 4.49 3.33 4.54 12.36
% of Normal 61% 56% 76% 64%
Dugor* Rainfall (inches) 4.64 5.78 5.93 16.35
Gilman* Rainfall (inches) 5.81 3.20 6.40 15.41
Luweech* Rainfall (inches) 5.21 2.98 5.91 14.10
Maap* Rainfall (inches) 7.86 6.06 3.70 17.62
North Fanif* Rainfall (inches) 6.03 6.04 5.02 17.09
Tamil* Rainfall (inches) 7.39 6.26 6.24 19.89
Outer Islands
Ulithi Rainfall (inches) 2.84 4.43 7.12 14.39
% of Normal 46% 87% 140% 88%
Woleai Rainfall (inches) 15.99 2.70 10.74 29.43
% of Normal 150% 36% 129% 111%
* Long term normal is not established for these sites

Climate Outlook:

The tropical cyclone threat for Yap during 2006 should be near normal, with the greatest threat occurring in the months of September through December. One or two tropical storms may form near Yap during May through July of 2006 bringing heavy rainfall. In the latter half of 2006, approximately 2 or 3 tropical cyclones should pass close enough to Yap (and/or its outer islands) to cause gales. The odds of a direct strike by any typhoon at Yap Island and at Ulithi is between 1 in 10 and 1 in 14 in any given year. The threat is even less further south at Woleai. While we expect no direct strikes by a typhoon of any island or atoll of Yap State during 2006, residents should always be prepared for the possibility.

Predicted rainfall for Yap State from May 2006 through April 2007 is as follows:
Inclusive Period
% of Long-Term Average
Yap and Ulithi
Woleai
May - Jun 2006 (end of dry season) 110% 90%
Jul-Oct 2006 (heart of next rainy season) 110% 110%
Nov - Dec 2006 (onset of next dry season) 100% 100%
Jan - Apr 2007 (heart of next dry season) 110% 100%
source: UOG-WERI