Area forecast discussion 
National Weather Service tiyan GU 
504 PM chst Thursday may 23 2013 


Synopsis...radar and satellite indicate isolated showers within 
the marianas marine zones. Satellite imagery indicates the band of 
showers associated with the weak surface trough moved north of the 
marianas marine zones. 


&& 


Discussion... 
reasoning follows continuity from the last 36 hours except the 
weak trough forecast to bring a slight chance of thunderstorms 
moved north of the marine zones. Models continue in general 
agreement with satellite imagery and continue to indicate trade- 
wind flow over the marianas forecast zones with a few embedded 
weak troughs the next several days. Since the first trough moved 
north of Saipan and no longer shows signs of thunder...and since 
the k-index and precipitable water on the morning satellite decreased to 26 and 
1.77 respectively since last night...thunder has been removed 
from the forecast for tonight. 


The next distinguishable trough on the models appears to arrive at 
the marianas about Tuesday or Wednesday. Except for the slightly 
wetter conditions from the weak troughs...expect generally dry 
conditions for the marianas the next several days. 




&& 


Eastern micronesia... 
synoptic configuration has not changed much during the past day or 
so. Trade-wind convergence zone remains focused between 2n and 8n. 
TUTT overlying all 3 forecast points is shearing any deep convection 
that develops to the north of 8n. Did extend scattered showers for 
Pohnpei tonight and for Kosrae through Friday night based on 
satellite trends and near term model solutions. Convection to the 
west of Majuro has stopped back building for now...but evening shift 
should monitor satellite imagery in the vicinity of Majuro just in 
case. Otherwise...do not expect weather setup over eastern 
micronesia to change very much during the next 5 days. Zone of 
trade-wind convergence should generally remain focused to the south 
of Majuro and Pohnpei. Trade-wind surge arriving by the weekend 
should dry things out a bit for the first part of next week. Did add 
a foot to combined seas for all 3 forecast points Sunday through 
Tuesday to account for increasing trade-wind waves and swell during 
this time frame. 


&& 


Western micronesia... 
a weak circulation was centered southwest of Pohnpei near 4n155e. 
Most of the attendant convection was located to the east of the 
center. A convectively inactive TUTT was moving westward away from 
Yap and Koror. Forecast for western micronesia generally follows 
persistence. Backed Chuuk winds overnight from east to northeast 
to factor in the wind field on the west side of the circulation 
centered to the southeast. Added mostly cloudy skies and isolated 
showers to the Chuuk forecast for Friday and Friday night. Believe 
remnants of circulation will provide some moisture and instability 
during that time frame. Forecasts for Yap and Koror remain 
unchanged. Models still keep deep-layer ridging in control over 
these locations. Remnants of circulation should dissipate before 
making as far west as Yap and Koror. 


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


$$ 


Devita/McElroy