Area Forecast Discussion
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FXPQ60 PGUM 220853
AFDPQ

Area Forecast Discussion
National Weather Service Tiyan GU
653 PM ChST Mon Oct 22 2018

.Marianas Synopsis...
It remains fairly quiet across the Marianas early this evening,
with a partly cloudy sky and isolated showers over the region.
Combined seas were mainly 3 to 4 feet. Tropical storm Yutu was
approximately 700 miles east-southeast of the Marianas.

&&

.Discussion...
Tonight through Tuesday night look relatively quiet across the
Marianas, with isolated showers. Then, things begin to deteriorate
as we get into the Wednesday to Thursday timeframe. Tropical Storm
Yutu, which is which is about 700 miles east-southeast of the
Marianas will approach the region Wednesday into Thursday. Have
ramped up winds and seas even further this forecast. There are now
tropical storm force winds in the Tinian and Saipan zones and
coastal waters forecasts. There will be breezy conditions at Guam
and Rota as well, and depending on the track of the storm, winds
may need to be increased or decreased at Guam and Rota.

Did not make many changes beyond Thursday, due to the presence of
Tropical Storm Yutu.

&&

.Marine...
Fairly benign Marine conditions are expected through Tuesday.
Then, expect wind and seas to increase into Thursday as Tropical
Storm Yutu approaches the region. Depending on the ultimate track
and strength of the system, the current forecast, could be
underdone, especially for the Tinian and Saipan waters. Marine
headlines may be needed at some point, even further south. Rip
current risk will likely become high by Wednesday and surf will
become hazardous. The latest guidance keeps swell higher on the
west side of the Marianas than the previous forecast even into
next weekend as the system moves away from the area.

&&

.Tropical systems...
Tropical Storm Yutu is currently located near 10N155E and is
moving to the west-northwest. It is expected to approach the
Marianas on Wednesday and move through the region Wednesday night
into Thursday.

Most of the guidance has come into agreement with the storm
expected to pass near or north of Saipan. The big disagreement
comes as to how near the passage will be. Several of the
models...ECMWF and NAVGEM are fairly close to Saipan while the GFS
and CMC are further away over the far northern Marianas Islands,
even closer to Pagan or between Pagan and Saipan. Obviously, a
distance of 50 or 100 miles or more makes a big difference on
impacts at any point, so there is still a lot of uncertainty at
this time.

&&

.Eastern Micronesia...
The major issue for part of the eastern half of Micronesia is
Tropical Storm Yutu. This storm is mainly affecting Pohnpei. This
afternoon the storm was 240 miles northwest of Pohnpei and moving
away. Pohnpei is on the eastern periphery of the storm and is
experiencing some of the outer rain-bands to the east of the center.
Expect numerous showers and isolated thunderstorms and gusty winds at
Pohnpei tonight. As Yutu moves away its influence on Pohnpei will
wane and showers and thunderstorms will decrease to isolated Tuesday.
Winds will also decrease by Tuesday. High pressure will build in by
Tuesday night and bring in partly cloudy skies by Wednesday night.

Further east a circulation could be found east of Majuro. This
circulation will remain weak and eventually become a surface trough.
The circulation and trough will still cause isolated showers and
thunderstorms tonight though Wednesday. Kosare will be far enough
from the activity that only isolated showers are expected there
through the forecast.

&&

.Western Micronesia...
The major issue for part of the western half of Micronesia is
Tropical Storm Yutu. This storm is mainly affecting Chuuk and was
280 miles east-northeast of Chuuk this afternoon. The tropical storm
will stay to the north of Chuuk but rain-bands to the south of Yutu
will push across the area tonight through Wednesday night. A monsoon
rain-band to the south of the tropical storm will keep scattered
showers and isolated thunderstorms at Chuuk through Friday. The
tropical storm and the associated monsoon will keep winds between
10 to 20 knots tonight through Friday with gust to 25 knots from
Tuesday through Wednesday night. The increased winds and proximity
of the tropical storms will also cause seas to increase slightly at
Chuuk the next few days.

The monsoon rain-band will remain south of Palau and Yap the next few
days, but will be close enough to Palau to generate isolated showers
and thunderstorms tonight through Saturday. A weak circulation to the
east of Yap will generate isolated showers and thunderstorms there
tonight. The tropical storm will move too far to the north of Yap...
and the monsoon rain-band will be too far south so only isolated
showers are expected at Yap Tuesday through Saturday. Enhanced flow
along the monsoon will elevate winds to 10 to 20 knots at Palau
Wednesday through Saturday.


&&

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

$$

Nierenberg/Ziobro


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