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000
FXPQ50 PGUM 060822
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
622 PM ChST Thu May 6 2021

.Marianas Synopsis...
Partly cloudy skies with fresh trade winds and isolated showers and
thunderstorms prevail across the Marianas this evening. Buoys show
seas between from 6 feet to just over 8 feet.

&&

.Discussion...
Model guidance continues to trend toward a drier weekend. The GFS now
shows around 0.5 to 0.75 inch of rainfall through Sunday night while
the ECMWF keeps rainfall amounts below 0.5 inch across the Marianas.
Most of the previously expected showers look to remain south of Guam,
however, unstable conditions will be over the islands for the next
several days. Based on this, decided to decrease showers to isolated
for the weekend, maintaining isolated thunderstorms through Monday
night. By Tuesday, a more stable atmosphere is expected across the
region.

&&

.Marine...
Latest buoy observations show seas from 6.66 feet at Tanapag to 8.14
feet at Ipan. Seas are expected to remain between 6 and 8 feet
through Friday night before beginning to slowly subside over the
weekend. This will continue to produce dangerous rip currents along
east facing reefs. Trade winds also remain near 20 knots with
frequent gusts to 25 knots. This is expected to continue through
Friday afternoon, when winds will subside slightly, just enough to
fall below levels hazardous to small craft operations.

&&

.Fire weather...
Gusty winds combined with a KBDI of 564 to maintain a high fire risk
today. Spotty showers along with higher RHs and fuel moisture helped
to keep conditions below Red Flag Warning criteria. Similar
conditions are expected for Friday as well. the Fire Weather Watch
will remain in effect and if conditions dry out a bit more, a Red
Flag Warning may be needed for Friday afternoon.

&&

.Eastern Micronesia...
Dry weather is seen at Majuro while a large cluster of showers and
thunderstorms is seen nearer Pohnpei and Kosrae. This is largely
associated with a band of trade-wind convergence along 5N and a surge
of trade winds to the north. Low-level cloud motions indicate some
showers moving at 25-35 kt. The outlook for both Pohnpei and Kosrae
remains quite wet as models show deep convection continually
developing in the area. Especially seen in the GFS, nearly-
stationary, or even slow eastward-moving, convective cells hint at
the continuing presence of strong upper-level westerlies the next few
days. While it is likely there will be some short-term lulls in
convection at both locations, the general pattern will remain wet.
For Majuro, dry trades will persist another couple of days, but
moisture will increase late weekend or early next week as the axis of
trade-wind convergence shifts closer.

As noted earlier, stronger trades will persist across the region the
next couple of days. For Pohnpei and Kosrae, with stronger gusts in
the showers, these conditions will be hazardous for small craft.
Even if winds are not particularly strong at the moment in your
location, quickly-approaching showers will bring rapidly-changing
conditions with stronger winds and much choppier seas. Have also
bumped sea heights up slightly, both to account for effects from the
stronger winds, but also to come into closer agreement with ECMWF
wave guidance which is averaging 1-2 ft higher than global wave. Over
the weekend, though, seas and winds will slowly improve.

&&

.Western Micronesia...
A pair of surface troughs near and southeast of Yap and Palau have
caused showers to increase across both areas while also increasing
local winds--particularly noted in the 00Z Yap sounding with near 40
kt low-level winds. Heavy showers and thunderstorms then stretch
eastward to near Chuuk where winds are also gusty. Chuuk showers and
thunderstorms will continue overnight, but should let up slightly
heading into the weekend as the east-west band of deeper moisture
shifts just south of Chuuk. However, models show showers moving back
in late in the weekend. In addition, upper-level winds could become
increasingly supportive of heavy showers and thunderstorms early
next week as an upper-level trough digs south to near 15N, placing a
50-60 kt jet streak northeast of Chuuk, just north of 10N. Such
positioning of features could help reinforce upward motions.

Off-and-on showers and thunderstorms will continue at Yap and Palau
the next several days with deep moisture staying focused between 7N
and 11N. Over the weekend, models continue to hint at varying degrees
of a monsoon trough trying to develop over the Philippines or even
stretching into the Palau/Yap region. While surface winds are
expected to decrease over the weekend, such a long-term trend will
lead to additional changes to wind forecasts. For now have opted to
expand the period of variable wind direction at Koror into next week
as models all show differing scenarios of gentle winds.

Stronger trades will persist at Yap and Chuuk the next day or 2 with
stronger gusts seen near showers. Have indicated that these winds
will lead to hazardous conditions for small craft. Winds are
ultimately expected to subside some over the weekend, beginning
Friday night.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...High Rip Current Risk through late Friday night for GUZ001>004.

     Fire Weather Watch through Friday afternoon for GUZ001.

Marianas Waters...Small Craft Advisory until 6 PM ChST Friday for
 PMZ151>154.

&&

$$

Marianas: Kleeschulte
Micronesia: Aydlett