Area Forecast Discussion
Issued by NWS
FXPQ60 PGUM 300551
Area Forecast Discussion
National Weather Service Tiyan GU
317 PM ChST Sat Jul 30 2016
Gentle trades and isolated showers are seen across the Marianas this
afternoon. A weak surface trough near 149E is generating a few more
showers and isolated thunderstorms east of the Marianas. Mariana
buoys show combined seas around 3 feet.
Inherited forecast needed little change as the near-term conditions
are holding steady. Expect isolated thunderstorms across the
Marianas tonight through Monday night as a weak trough enters the
area this evening. Gentle east winds tonight and Sunday will shift
to the northeast Monday and north on Tuesday.
Long-range forecast remains uncertain. Both GFS and ECMWF show a
monsoon-type circulation north or northeast of the Marianas by
midweek giving southwest to west winds over Guam and the CNMI. There
remains a bit of variation in wind speeds and moisture between the
models. ECMWF still favors moderate to fresh west winds locally vs
the gentle west winds in the GFS. Forecast maintains a blend of the
two. Forecast also maintains a dry bias for now. This could be
adjusted depending on the evolution of the monsoon circulation and
development of a monsoon tail.
Still expect a WSW swell at 1 to 2 feet for Sunday night through
Wednesday, generated by Tropical Depression 06W east of the
Philippines. Also, 4-ft seas are creeping back into the eastern
waters through Monday.
A subtropical low remains northwest of Wake Island near 24N159E with
moderate to strong easterly winds and scattered showers in the area
near Wake Island. Gentle to moderate trade winds prevail across
Chuuk, Pohnpei and Kosrae States and Majuro. Also, there is a weak
trade-wind trough and widely scattered showers over the northern
Marshall Islands, and another trough/disturbance is just over the
Date Line near 10N175W. Models solutions differ significantly, but
the northern RMI trough and the disturbance just east of the Date
line will likely drift westward and showery weather should remain
along and north of 10N in the coming days. Mild weather conditions
are expected for Chuuk, Pohnpei, Kosrae and Majuro with just spotty
showers and thunderstorms at times this week. Majuro Buoy shows
combined seas of 4 to 5 feet.
The Chuuk forecast discussion is in the Eastern Micronesia
TD 06W at 14N127E is moving slowly away from Western Micronesia but
a Monsoon Trough remains between Yap and Koror. The complex pattern
of low-level convergence and upper-level divergence over far Western
Micronesia will persist another day or two, and there will be patchy
areas of showers this weekend. Models indicate that light winds and
mild weather will develop for Yap and Koror early next week.