170
FXPQ50 PGUM 230744
AFDGUM

Area Forecast Discussion
National Weather Service Tiyan GU
544 PM ChST Sun Feb 23 2025

.Marianas Synopsis...
Partly cloudy skies and breezy conditions continue across the
Marianas. Scattered showers are seen in an east-west oriented
convergence band just south of Guam coastal waters, but to the north,
dry conditions prevail. Surface observations and scatterometry show
fresh to strong trade winds across much of the CNMI.

&&

.Discussion...
A dry and breezy trade wind regime continues, with a brief lull in
wind speed expected for Monday and Monday night. Winds and seas will
diminish long enough for marine and surf hazard products to expire
Monday, but most will need to be re-issued around midweek as trades
begin to surge again, associated with strong eastward-moving high
pressure passing north of the CNMI. Showers are expected to remain
isolated throughout the forecast period, with chances increasing in
the latter half of the week due to nearby shear line activity.

&&

.Marine/Surf...
A Small Craft Advisory remains in effect through early Monday
morning, with combined seas of 7 to 10 feet expected tonight.
Additionally, a High Surf Advisory remains in effect for north facing
reefs of the Marianas, and a High Rip Current Risk is in place for
north and east reefs through tonight. Fresh to strong winds will
diminish overnight, becoming moderate to fresh Monday through Monday
night with a temporary relaxation in the pressure gradient. Northerly
swell will weaken in the meanwhile. By Tuesday night, trade winds
will begin to surge again, and a Small Craft Advisory will likely
need to be re-issued. Stronger trade swells will arrive as the next
major northerly swell moves into the region by around midweek, which
will likely necessitate the re-issuance of surf hazard products.
However, this will be preceded by surging trade winds that will
likely bring seas hazardous to small craft.

&&

.Fire weather...
Only a trace of rain was recorded yesterday, allowing the KBDI to
rise to 661, which remains in the high category. The convergence
boundary and associated showers in today`s forecast have shifted
south and east of the Marianas, allowing drier, more favorable fire
weather conditions to set in to the north over Guam. Relative
humidity values fell below 60 percent this afternoon, which, in
combination with elevated gusty winds are allowing Red Flag criteria
to be met, and a Red Flag Warning was issued for today. The fire
threat will be higher in the southern portions of Guam over the next
several days. Winds are expected to diminish for tomorrow, but a Red
Flag Warning may need to be reissued if sustained wind speeds remain
higher than expected.

&&

.Eastern Micronesia...
Eastern Micronesia remains mostly dry north of 5N, with scattered
showers and a few thunderstorms south of 5N, mainly south of Pohnpei
to southwest of Kosrae. Around midweek, models indicate that a band
of trade-wind convergence will develop and move into Kosrae and
Pohnpei, remaining south of Majuro. The GFS and ECMWF want to bring
high-end scattered showers to both locations. However, the models
have been overestimating shower potential across the region for some
time now. Therefore, maintained POPs (Probability of Precipitation)
around the 30 percent range. Majuro looks to remain dry through the
week. By the end of the week, the entire region will return to a dry
trade-wind pattern.

Otherwise, breezy conditions with mostly fresh to occasionally strong
winds will prevail across Pohnpei and Kosrae through Monday and at
Majuro through Tuesday as a trade-wind surge associated with a
transiting mid-latitude high continues. the high will continue to
move east, allowing the surge to ease over Pohnpei and Kosrae
Monday, lingering a bit longer at Majuro. Meanwhile, a long-period
north swell currently in Pohnpei and Kosrae states will transit
through the region, combining with trade-wind swell and wind waves to
produce seas hazardous to small craft operations. Due to the
combination of seas and winds, a Small Craft Advisory remains in
effect for all three locations. Pohnpei and Kosrae should see
decreasing winds and seas by Monday afternoon, with Majuro seeing
some relief Tuesday afternoon.

We will continue to monitor conditions at Majuro and across the
Marshall Islands for the possibility of wave runup and possible
inundation later this week due to above normal high tides expected
around Thursday into Saturday.

&&

.Western Micronesia...
A trade-wind surge remains the main synoptic feature affecting much
of western Micronesia. Occasional upticks in low-end scattered showers
are expected at Palau and Yap for much of the forecast period, as
minor perturbations in the trades make their way across. By midweek,
winds are expected to become strong to near-gale during the peak in
pressure gradient during the passage of the aforementioned
subtropical high (mentioned in Discussion) north of the tropics. A
mostly dry regime induced by diffusive trades is expected at Chuuk
the next several days, before shower and thunderstorm coverage
increase significantly as a tropical disturbance forms nearby before
the next weekend.

Combined seas of 7 to 9 feet near Palau and Yap are expected to
increase another 2 to 3 feet by Tuesday night, as another northerly
swell pulse arrives to the region. Conditions still remain hazardous
for small craft in Chuuk coastal waters, so the Small Craft Advisory
remains valid through late Monday afternoon. The long-period
northerly swell currently producing elevated seas near Chuuk is
expected to diminish beginning Monday afternoon, falling below 10
feet by Monday night. Surf also remains hazardous along north facing
reefs of Chuuk through late Monday night, falling below 9 feet by
Monday night.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...Red Flag Warning until 7 PM ChST this evening for GUZ001.

     High Rip Current Risk through late tonight for GUZ001.

     High Surf Advisory until 5 AM ChST Monday for GUZ001.

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

     High Surf Advisory until 5 AM ChST Monday for MPZ001>003.

Marianas Waters...Small Craft Advisory until 5 AM ChST Monday for
 PMZ151>154.

&&

$$

Marianas: DeCou
East Micronesia: Kleeschulte
West Micronesia: Montvila