Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

FXPQ60 PGUM 280737

Area Forecast Discussion
National Weather Service Tiyan GU
533 PM ChST Fri Apr 28 2017

.Marianas Synopsis... Southeast winds prevail over the Marianas this
afternoon. Low-level convergence will produce periods of scattered 
showers over Guam and Rota this evening. Isolated thunderstorms are 
possible across all the island through the night. 


Afternoon satellite imagery showed a large area of scattered showers
and isolated thunderstorms just northwest of the local area. Small
segments of these showers were getting close to Guam and Rota and
lightning was detected just to the northwest of Guam. While the 
large area of showers will remain north and northwest of the 
local area models hint at a brief period of scattered showers this
evening near Guam and Rota. With the model and satellite data 
agreeing, added scattered showers to Guam and Rota through 12Z. 
Since lightning was detected have isolated thunderstorms through 
tonight for all the islands. 

Models agree on a return to a drier weather pattern with isolated
showers expected through at least mid-week. Southeast winds will 
prevail through Saturday with east winds returning sometime on 
Saturday night. 


Scattered showers and isolated thunderstorms are expected in the 
Guam and Rota waters this evening, especially to the west of the 
islands. Isolated thunderstorms are possible through the whole 
night across all the coastal waters.

Observations this afternoon from Ritidian, Tanapag, and Ipan buoys 
indicate combined sea heights around 4 feet. Expect combined seas 
of between 3 to 5 feet through the weekend. An east swell of 3 to
5 feet is expected through Tuesday. Tanapag buoy does show a 
northeast swell as does the WW3 model guidance. Model data indicate
that this swell will end Saturday. Surf will be 5 to 7 feet on east
facing reefs with little change the next few days. The surf on all
other will be around 1 to 3 feet. 

Southeast winds will prevail through Saturday becoming east Saturday
night. Wind speeds will be between 10 to 15 knots through Tuesday.


.Eastern Micronesia...
In the near term, a disturbance to the east of Kosrae appears to 
be weakening and should have little impact on the area. However, 
scattered showers and isolated thunderstorms are developing further
south between Kosrae and the equator and if these hold together, 
could bring rain to Kosrae later.

Otherwise, an overall dry trade wind pattern is expected through
Saturday night/early Sunday when another trade wind disturbance
will bring a renewed chance of showers and thunderstorms, mainly 
for Kosrae and Pohnpei.  This feature will move through by Tuesday,
with a return to more isolated showers. 


.Western Micronesia...
The remnants of Tropical Depression Muifa are moving away from the
region, but the area close to what is left of the circulation 
center still has plenty of showers and thunderstorms. South of the
main center there were some scattered showers near Palau, and some
isolated showers near Yap. Overall, rain chances should decrease,
though there could be some afternoon convection over Palau on 
Saturday. Beyond that, a drier pattern appears to return.


Marianas Waters...None.

National Weather Service Glossary of Abbreviations