Strong Wind in Guam, February 6 to 10, 2023

Area Forecast Discussion
National Weather Service Tiyan GU
721 AM ChST Mon Feb 6 2023

.Marianas Synopsis...
Moderate trades prevail in the Marianas. Satellite imagery and
Doppler radar indicate fast-moving sprinkles across Rota's coastal
waters. Buoys show seas are between 7 and 8 feet.

&&

.Discussion...
Little change was made to the forecast. Introduced scattered showers
for this afternoon, as a weak trough is moving through from the east,
with its southern sector producing slight convergence that may trip
over Guam and Rota as well. The rest of the forecast remains
unchanged, with minor wrinkles expected to bring isolated showers
through much of the forecast period. Thunderstorm potential remains
negligent due to lack of updraft potentials and seasonably dry mid-
levels. Variability in the trades may occasionally bring gusts to 30
mph the next several days, with more substantial winds expected to
arrive towards the weekend as a high pressure system moves off the
coast of Japan and increases the pressure gradient with the tropics.

&&

.Marine...
Combined seas of 6 to 8 feet will build an additional foot or two
late this week as trade swell strengthens and a longer-period north
swell makes it to the region by early next week. As the winds and
seas build, this may introduce sea conditions hazardous to small
craft by the weekend. A High rip current risk will remain for east
facing reefs of the Marianas for the rest of the week, briefly
dropping to moderate risk Wednesday as trade swell temporarily
weakens but picks up once again thereafter.

&&

.Eastern Micronesia...
Morning satellite imagery showed an area of clouds and showers over
the eastern half of Micronesia, mainly over the Marshall Islands.
Scatterometer data over the same area showed an area of winds with
speeds between 20 to 30 mph. The area of winds are associated with a
trade-wind surge that continues to develop over the eastern half of
Micronesia. The showers are the result of these winds generating low-
level convergence.

Expect breezy conditions at Pohnpei, Kosrae, and Majuro today. A
continuous progression of high pressure centers passing across the
Northwest Pacific north of the area will keep the pressure gradient
elevated throughout the forecast. The will cause the breezy
conditions to be persistent at the three forecast locations through
the coming weekend.

Low-level convergence associated with the increased winds will bring
scattered showers and isolated thunderstorms to Majuro through
Sunday. This convergence and associated shower activity will progress
westward. The morning satellite imagery showed only a few clouds
over Pohnpei and Kosrae. Models show the showers increasing over
these two locations as the convergence increase. The low-level
convergence will persist through the forecast. The convergence
combined with the occasional ITCZ pattern and deep-layer moisture
will continue to produce a higher chance of showers and thunderstorms
at Pohnpei and Kosrae through at least Sunday.

Persistent winds between 25 and 30 knots are expected over the
coastal waters of Pohnpei, Kosrae, and Majuro through at least
Friday. Friday is the end of the forecast, but models show frequent
gusts to 25 knots possible over the three forecast locations through
at least Sunday. The higher winds will generate higher wind waves.
The wind waves combined with increasing swell will produce higher
combined seas. The winds and most likely the seas will be hazardous
to small craft over Pohnpei, Kosrae and Majuro through the week. As
mentioned earlier, the coastal forecast only goes to Friday, but
these elevated winds and seas and any associated advisories are
likely to persist into the coming weekend.

The northeast swell at Kosrae has increased enough so that surf is
hazardous on east facing reefs of Kosrae. Expect the surf to remain
hazardous on east facing reefs of Kosrae through the week. As
mentioned above, seas and swells will increase over the region, which
will produce the possibility of hazardous surf developing at both
locations.

&&

.Western Micronesia...
Satellite imagery showed an areas of on and off showers and
thunderstorms south of Palau, Yap, and Chuuk. This activity is
associated with low-level convergence north of a near-equatorial.

As Palau is further south, activity developing north of the near-
equatorial trough will occasionally expand northward enough to brush
Palau. Expect a higher chance of showers and thunderstorms at Palau
tonight, Thursday and Thursday night. Yap is further north with
activity passing south of that location. Only isolated showers are
expected through Friday. Models show a circulation developing along
the near-equatorial trough by the end of the week. Convergence north
of it will bring a higher chance of showers and thunderstorms to
Palau and Yap Friday night through Sunday.

Further east...drier air will keep showers isolated over Chuuk through
tonight. The area of increased trade-winds mentioned above over
eastern Micronesia will push west and make it to Chuuk by Tuesday.
This will produce breezy conditions at times over Chuuk Tuesday
through the end of the week. Low-level convergence associated with
the surge will bring a higher chance of showers and thunderstorms
Tuesday through Wednesday night. The circulation development
mentioned above will begin further east. Low-level convergence north
of it will bring a high chance of showers and thunderstorms at Chuuk
Thursday through Friday. Trade-wind convergence will continue the
higher chance of showers and thunderstorms through Sunday.

As the trade-wind surge over eastern Micronesia expands westward, it
will cause winds between 25 and 30 knots over the coastal areas of
Chuuk Tuesday through Friday, possibly longer. The increase in winds
will generate higher wind waves. The wind waves combined with
increasing swell will produce higher combined seas. The winds and
most likely the seas will be hazardous to small craft over Chuuk
Tuesday through Friday.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...High Rip Current Risk through late Tuesday night for GUZ001.

MP...High Rip Current Risk through late Tuesday night for MPZ001>003.

Marianas Waters...None.
&&

Marianas: Montvila
Micronesia: Ziobro