Weather

715 
fxpq60 pgum 112145 
afdpq 


Area forecast discussion 
National Weather Service tiyan GU 
745 am chst sun Oct 12 2008 


Synopsis... 
pgua WSR-88D shows scattered showers to the west of the marianas. 
Lesser isolated shower coverage is moving in from the east as a 
surface trough of low pressure exits the area. 


&& 


Discussion... 
gfs40 brings another little surface trough of low pressure just 
south of the marianas around Tuesday. Most of the showers should 
pass to the south of Guam but it may merit mention of scattered. 
Left it isolated for now but this is probably the major forecast 
problem for the day shift. This is currently the activity near 
Chuuk which then moves toward the marianas for Tuesday. 


Overall pattern is starting to resemble a dry season pattern now. 
Day 10 of the gfs40 features a cold front pushing all the way down 
to 25n. Much of the precipitation is being caused by trade-wind 
convergence rather than troughs or wet-season type features. Will 
need to watch and see if wet season tries to make a resurgence 
later. 


&& 


Marine... 
swells will increase as trade winds continue to blow east of the 
marianas. Surf is expected to remain below hazardous levels. 
Combined sea heights are also expected to remain below Small Craft 
Advisory criteria. Mariners should still be attuned to the 
changing conditions however. 


&& 


Eastern micronesia... 
a semi dry season pattern is taking shape over eastern micronesia. 
As confirmed by the latest upper air data from kwajalein...a dry 
moderate trade-wind surge has already reached the northern Marshall 
Islands and will continue to move southwestward into the southern 
Marshalls this evening. Weak convergence along the leading edge of 
the surge is expected to create some clouds and a few showers this 
evening over Majuro. Nice weather will then follow and last through 
Monday night. 


Even though both infrared satellite and Quikscat imagery have revealed a 
weak surface trough approaching Kosrae from the east this morning... 
the trade surge sweeping southwestward is expected to dissolve it 
and dry things out tonight into Monday evening. Weak trades over 
Pohnpei are also going to pick up tonight as the surge makes it way 
there late tonight. Afterward...passing trade-wind showers regime 
will return from east to west toward midweek. 


In response to the surging trade winds...seas will rise to between 5 
and 6 feet across the region by Monday morning. Surf along north and 
east facing reefs will also reach 6 to 7 feet by Monday evening but 
below high surf advisory criteria. 


&& 


Western micronesia... 
a strong trade-wind disturbance will continue to impact Chuuk and 
surrounding waters with showers...thunderstorms and gusty winds through 
this afternoon. Conditions are expected to greatly improve tonight 
as it pushes farther northwest of the island. Drier moderate trades 
will provide a brief break on Monday. However...a trend toward more 
frequent trade-wind showers will come back by midweek. 


In the wake of the departing trough...a ridge is forming over Yap 
and Palau this morning. Hazy sunshine can be expected over the area 
today as the ridge strengthens. The disturbance currently over Chuuk 
will track west-northwestward and arrive at just south of Guam on 
Tuesday. Therefore clouds will begin to increase with showers 
approaching by midweek. For now...the brunt of the precipitation might pass 
north of Yap. 


&& 


Gum watches/warnings/advisories... 
GU...none. 
Marianas waters...none. 
&& 


$$ 


Stanko/chan