Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service tiyan GU
609 am chst Thursday Apr 17 2014

Marianas synopsis...
the tropical disturbance northwest of Chuuk near 10n149e...jtwc invest
area 98w...is finally displaying a fairly concentrated area of
deep convection on infrared satellite imagery...and the northwest
fringe of that area is now seen on Guam radar. Scattered showers
and a few thunderstorms associated with a weak trough are also
seen on radar well west of the islands...but only isolated showers
are present in the marianas waters. Seas have increased to 5-7 feet
at the ritidian and Saipan buoys...and remain around 4 feet at ipan.

&&

Discussion...
no changes were needed...as models are in consistent agreement
with previous runs and each other...still keeping 98w weak is it
slides by south of Guam the next couple of days...but bringing
scattered showers and isolated thunderstorms to the marianas Friday-
Sat.

&&

Marine/surf...
seas are rising as north swell ramps up to 5 feet today...peaks at
6 feet tonight...then drops back to 5 feet on Friday. Surf will get
close to hazardous...rising to 6-8 feet tonight...and will need to
be closely watched.

&&

Eastern micronesia...
the near-equatorial trough remains stretched across Pohnpei and
Kosrae to south of Majuro at the Equator. Showers and thunderstorms
are present south of the trough axis...south of Pohnpei and Kosrae.
More showers are seen near Majuro and towards the date line.
Scattered showers were added back to the Majuro forecast for this
morning as this cluster of showers moves through. Drier trades are
found behind these showers towards the date line. A drier pattern
will be in place at Majuro for the weekend. For Pohnpei and
Kosrae...forecast remains unsettled the next few days. The near-eq
trough will remain nearly stationary until Friday. Models show the
trough will shift southwest Friday and Saturday. In the meantime
GFS still shows a circulation developing southeast of Kosrae
moving northwest on Saturday and Sunday. Forecast in the middle to
long range hinges on whether this feature develops and passes over
these locations...bringing showers and thunderstorms...or remains
a trough passing near or south of these locations.

&&

Western micronesia...
showers and thunderstorms persist near the circulation centered
between Guam and Chuuk. 12z ascat shows the center at 10n149e. A
near-equatorial trough runs from 9n130e...across Yap...through the
circulation and across Chuuk into eastern micronesia. Models backed
off the moisture at Chuuk today...going well with morning satellite
imagery. However...12z Chuuk sounding showed a precipitable water of 2.62 inches.
Moisture content seems ripe for development of more showers today.
Day shift will have to keep close eye in case an update is needed
for scattered showers. Models show the circulation heading west-northwest
through Saturday. As it does...conditions will gradually improve
at Chuuk into the weekend. Forecast at Yap and Palau maintains a
dry bias with light winds through the weekend. A more southerly
track of this circulation would bring more showers to both
locations over the weekend. For now...no changes to the Koror and
Yap forecasts.

&&

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

$$

Middlebrooke/M. Aydlett