Area Forecast Discussion
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FXPQ60 PGUM 250852

Area Forecast Discussion
National Weather Service Tiyan GU
651 PM ChST Tue Jul 25 2017

.Marianas Synopsis...
An area of weakening showers was located to the north of the
Marianas was evident on satellite imagery. Otherwise, a mainly
partly cloudy sky was observed. Seas were generally 3 to 4 feet at
the buoys.


Overall, quiet weather will remain in places across the Marianas
into next week. An area of showers with embedded thunder moved to
the north of Saipan earlier. This area is weakening and should
continue to do so.

The Marianas will remain under a ridge with Typhoon Noru and
Tropical Storm Kulap to the north and Invest 99W to the west. The
airmass gets really dry at all levels, especially as the week
progresses. Isolated showers or even a thunderstorm can not be
ruled out Wednesday or Thursday, especially if the GFS is correct
and there is even modest UVV. No significant changes were made to
the prev fcst.


Increasing northerly swell is expected by the end of the week from
Typhoon Noru. Combined seas of 3 to 5 feet are expected for the
next few days. By the weekend we could be looking at high surf
conditions on north facing shores.


.Eastern Micronesia...
Two weak trade-wind disturbances will continue to trigger periodic
showers and thunderstorms near Chuuk and Pohnpei thru Wednesday
afternoon. By Wednesday evening, a surface ridge currently over
Kosrae should shift westward and provide partly cloudy skies for
both places. Farther east, a pronounced trade-wind convergence zone
can be seen between the equator and 5N; stretching east-
northeastward from south of the Marshall Islands at 174E across the
Date Line to beyond 160W. Convection associated with this zone is
going to reach Majuro by Wednesday afternoon, Kosrae by Wednesday
night, Pohnpei and Chuuk toward this weekend. Anticipate rainy
weather to persist across the Marshall Islands thru this weekend,
Kosrae, Pohnpei and Chuuk thru early next week.

The astronomical high tide or King Tide cycle is gradually
decreasing in heights but will still be high enough to affect the
Marshall Islands thru Thursday morning. Combining with a 6 to 7-foot
surf generated by a moderate east-southeast swell, splashing waves
could still occur along coastal roads and near the airport during
high tides.


.Western Micronesia...
The monsoon circulation, Invest area 99W has moved farther north
over the Philippine Sea to near 13N130E this evening. In response,
the fresh monsoonal southwest winds have also shifted northwest of
Koror and Yap. Outflow boundaries generated by convection west of
Koror can still trigger waves of showers and thunderstorms near
Koror and Yap thru Wednesday afternoon. Starting Wednesday night, a
surface ridge already southeast of Yap near 5N140E should build
northwestward and bring much quieter weather for both locations into
the weekend.

Decreased southwest winds and swell across the area have allowed
seas to subside below hazardous levels for small craft this evening.
Surf heights are also expected to fall this evening and should drop
below hazardous levels by Wednesday morning.


Marianas Waters...None.


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