Area Forecast Discussion
Issued by NWS Tiyan, Guam

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000
FXPQ50 PGUM 212214
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
814 AM ChST Fri Mar 22 2024

.Marianas Synopsis...
Partly cloudy skies reign over the Marianas. Satellite imagery shows
in increase in cloud cover. Winds are, at the time of this writing,
light.

&&

.Discussion...
A weak disturbance near Satawal is flinging some moisture in the
direction of Marianas. This has increased the cloud cover of the
islands. Next, a shear line is moving southward from Alamagan to over
the main islands of the Marianas. This mixture, depending on arrival
times of both features may be the spark we need to break out of this
dry spell we are in, however, the timing of these two features is
very tricky to nail down when they will intersect. Current analysis
suggests they the shear line will get here first, then the moisture.

&&

.Marine/Surf...
A high risk of rip currents plus High Surf and Small Craft Advisories
remain in effect through Sunday night.

This is where the main concerns are. A strong low pressure system off
the coast of Japan is building a large fetch aimed at the Marianas.
This fetch (where swells are created) is anticipated to create 10 to
13 feet seas with the potential of becoming 15+ feet. If fetch
produces these larger waves, then a foot or two of coastal inundation
along north facing reefs may happen. If this event becomes an over
achiever High surf warning and hazardous seas warning may be needed.

&&

.Fire weather...
A fire weather watch is in effect through Sunday night, this may get
elevated.

With no rain yesterday, the KBDI was allowed to increase to 655,
this remains in the high category. Current relative humidity is below
60 percent. Wind are expected to build over today and continue to be
elevated through this shear line event at least and possibly through
most of next week. A wetting rain maybe possible with this event,
assuming a moisture injection from Micronesia happens as the models
suggest. However models are also suggesting that the moisture maybe
delayed at bit, and if so, we may just miss the showers altogether.

&&

.Eastern Micronesia...
The main weather feature affecting Eastern Micronesia is a trade-wind
trough south of Majuro. The showers with this trough are confined
south of 6N, so they may brush Kosrae, but will not affect Pohnpei or
Majuro to any great extent.

Around Sunday, Pohnpei could briefly have some gusts to 25 knots,
probably from the shear line. Otherwise benign marine conditions
will prevail throughout Eastern Micronesia.

&&

.Western Micronesia...
There are scattered showers near Chuuk right now, and they could last
through Saturday. There might be another brief blip Wednesday night,
but otherwise it will be getting drier again at Chuuk.

Yap could see scattered showers Saturday night through Monday,
probably with the shear line. If interaction with the weak
circulation occurs, Yap could see some substantial rainfall. Until
then, I`m going to take the under on that bet, and guess that the
rain amounts will be... underwhelming.

Koror, Palau could receive scattered showers Sunday through Monday
night, otherwise they will be fairly dry. The same general thoughts
apply as at Yap. The rainfall could be substantial if the right
interaction pops up, but for now I`ll take the under. I think there
will be scattered showers, but the accumulations will just not be
inspiring.

Yap could have a Small Craft Advisory on Saturday night and Sunday.
Otherwise, marine conditions at Chuuk will be challenging thanks to
the proximity of the shear line, but less than hazardous, while at
Palau benign marine conditions will continue.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...Fire Weather Watch through Sunday afternoon for GUZ001.

     High Rip Current Risk from this evening through late Sunday night
     for GUZ001.

     High Surf Advisory from 6 PM this evening to 6 AM ChST Monday for
     GUZ001.

MP...High Rip Current Risk from this evening through late Sunday night
     for MPZ001>003.

     High Surf Advisory from 6 PM this evening to 6 AM ChST Monday for
     MPZ001>003.

     Small Craft Advisory from 6 PM this evening to 6 AM ChST Monday for
     MPZ003.

Marianas Waters...Small Craft Advisory from 6 PM this evening to 6 AM ChST Monday for
     PMZ151>154.

&&

$$

Marianas: Bowsher
Micronesia: Stanko


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