Area Forecast Discussion
Issued by NWS
FXPQ60 PGUM 291955
Area Forecast Discussion
National Weather Service Tiyan GU
555 AM ChST Sun Apr 30 2017
Moderate trades and isolated showers are present across the Marianas
this morning. Combined seas are running near 4 ft at the buoys.
The basic forecast of partly cloudy skies with isolated showers is
unchanged for the time being, as no significant weather systems are
expected to affect the region for the next week or so. Marine
conditions will also be stable, with only a slight rise in seas
Monday night and the next several days beyond that.
Upper-air sounding data reveal much drier air above 700mb over Chuuk
and Pohnpei. This drier air mass should maintain fair weather near
Chuuk thru tonight and Pohnpei for today. To the east, the leading
edge of a fresh trade-wind surge in the form of a trade disturbance
is approaching Kosrae. Expect showers associated with this system to
linger near Kosrae thru Monday afternoon. This same system will also
bring showery weather to Pohnpei by tonight and Chuuk by Monday.
For Majuro, anticipate decreasing clouds and showers this morning
as drier northeasterly trade winds begin to dominate the area. After
the passage of the disturbance, drier trades will then progress
westward from Majuro to Kosrae before midweek and Pohnpei by midweek.
After that, model consensus is extending a near-equatorial trough
currently across far Western Micronesia eastward to the southwest of
Pohnpei. Under this scenario, modest converging trade winds northeast
of this trough might trigger periodic showers near Chuuk and Kosrae.
Fresh trade winds surging across the Marshall Islands will prolong
hazardous conditions for small craft near Majuro at least thru
today. Day shift needs to examine ASCAT satellite imagery this
afternoon to see if these trades will persist near Majuro. If so,
need to extend headline for tonight. Building trade-wind swell and
wind waves generated by this surge will also create hazardous surf
on Kosrae thru tonight.
Modest converging winds north of a weak near-equatorial trough might
spark a few showers near Koror until Monday evening and Yap today.
Aided by afternoon heating, a thunderstorm or two is also possible
near Koror today and Monday. A much drier air mass above 700mb will
gradually migrate westward tonight and Monday. This feature should
introduce a more stable environment for Yap by Monday afternoon and
Koror by Monday night.