Scientific Forecaster Discussion
Area forecast discussion
National Weather Service tiyan GU
533 am chst Tuesday Sep 16 2014
radar shows widely scattered showers and isolated thunderstorms
over the east and southeast parts of the coverage area with larger
areas of rain northwest of Guam. Satellite infrared shows several areas
of clouds and showers east of the marianas to beyond 155e. Ascat
analysis indicates the weak circulation associated with invest
area 96w was near 11n141e and drifting westward. VAD gradient
winds are southeast 15-20 knots. Buoys show combined seas of 4 to 5 feet
with directional components from west and east-northeast.
models indicate wet monsoon-type weather will continue the next
couple days while invest area 96w gradually develops and drifts
westward and then northwestward. Only minor changes were made to
the public forecast at this time.
mixed sea conditions are expected this week. Adjustments were made
to wave grids based on ww3 model which indicates several different
smallish swell components could affect sea conditions besides the
basic east and west swells already in the forecast. Nothing big is
in the forecast but subtle changes to sea conditions will need to be
monitored. Refreshed wind grids with latest GFS model data.
latest model runs initialize reasonably well with infrared satellite
imagery and 12z ascat analysis. A surface trough stretches from
near Pohnpei...over Kosrae and Majuro to near the date line at 11n.
Shower coverage has decreased along the trough so showers were
reduced to isolated today at Majuro...but maintained isolated
thunderstorms. Isolated thunderstorms were added to Kosrae and
Pohnpei with their proximity to the trough. More showers are
crossing the date line east of the trough and will reach Majuro
tonight. Models forecast drier weather for late Wednesday and Thursday
across the region. Later in the week models show a convergent
pattern setting up that could bring more moisture by the weekend
to the Marshall Islands and Kosrae.
dry weather is seen at Chuuk this morning with surface ridging
wedged in across the state. Dry weather will persist through
tonight. Unsettled weather will develop across the state ahead of
a surface trough approaching from the east. Drier weather will
return for the end of the week. Forecast is questionable in the
long term as models show a convergent light and variable wind
pattern Friday and Saturday in eastern micronesia. Models for now
keep associated weather near and east of Pohnpei.
At Koror and Yap...a broad circulation centered near Yap at
11n139e this morning remains the main weather feature. Scattered
showers and isolated thunderstorms have reached both locations
this morning. Models still depict a wet pattern at least through
tonight for both locations. Stronger southwest winds will build in
behind the disturbance as it continues towards the west-northwest
on Wednesday. Ridging will usher in drier weather for the end of