814
FXPQ50 PGUM 262119
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
719 AM ChST Thu Jun 27 2024

.Marianas Synopsis...
Satellite shows partly sunny skies and isolated showers over the
Marianas Waters today. An upper-level low is seen to the north which
is triggering isolated thunderstorms north of Anatahan and south of
the Marianas Waters.

&&

.Discussion...
A relatively dry patter is hanging on, and will continue to do so
through the weekend. Next week is looking a little wetter though, no
surprise as we slip toward wet season. An upper-level low will
provide a slight chance of thunderstorms starting Friday night as it
moves slightly north of west. All eyes will be on western Micronesia
next week, watching to see if we really get a monsoon trough, or if
we just get a vague look alike that quickly fizzles. That could
profoundly influence how wet the week after next is for us.

&&

.Marine...
Seas of 5 to 7 feet will begin to diminish tonight as winds subside
from moderate with strong gusts down to just moderate. Seas will
reach 3 to 5 feet by late next week, and winds will become gentle to
moderate by Saturday. This will restore the benign marine conditions
that sailors were previously enjoying.

&&

.Eastern Micronesia and Chuuk...
Scattered showers and isolated thunderstorms continue to focus
around trade-wind troughs, one moving through Chuuk today and the
other moving through Pohnpei around noon, then deepening before
reaching Chuuk Friday. Added thunderstorm potentials in for those
periods based on satellite trends and in anticipation of these
features. A moderate surge in the trades is also aiding low-level
convergence, as illustrated in overnight scatterometry data.
Satellite-derived total precipitable water (TPW) data and model
trends shows relatively drier air moving in to the east of Majuro,
dampening shower potentials this afternoon to Friday morning, before
the arrival of another trough. Over the weekend and into next week,
models continue to show an ITCZ pattern rebuilding, increasing shower
and thunderstorms potentials once again.

Scatterometry data indicates moderate to fresh winds across the
region. Winds are expected to decrease to light to moderate over the
weekend. Combined seas of 4 to 6 feet are expected over the next
several days. A slight decrease in swell and wind waves over the
weekend will cause seas to subside to between 3 and 5 feet for
Chuuk, Pohnpei, and Kosrae.

&&

.Western Micronesia for Yap and Palau...
The bulk of convection has shifted north, in an area of convergent
trades that trail behind Invest 98W and attendent troughs. This will
provide a lull in weather for far western Micronesia, so only
expecting isolated to scattered showers for Yap and Palau today.
Additionally, added a slight chance of thunderstorms for Yap based on
a few thunderstorms showing up on satellite imagery southeast of
coastal waters. The latest WRF model run, indicates a weak
disturbance gradually developing in the southwest corner of the
region. This is expected to anchor a trough that will extend across
Palau and Yap and will continue to produce showery weather. So far,
ECMWF is the only model keying on elevated gust potentials for Yap,
up to 25 kts. This is something to continue to watch out for,
especially near heavier showers and thunderstorms. The overall
pattern resembles a monsoon pattern trying to establish itself. We
are in the right season for it, but still looking for a well-defined
trough connecting to southeast Asia, ushering in westerly, monsoon
moisture. This trough we are monitoring, has the right orientation,
but looks to be quickly shoved off to the northwest as an ITCZ
wedges itself along the equator early next week.

Buoy data indicates seas between 4 and 6 feet and is expected to
decrease to 3 to 5 feet over the weekend, and down to 2 to 4 feet by
Monday.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...None.
MP...None.
Marianas Waters...None.
&&

$$

Marianas: Stanko
Micronesia: Cruz