NWS Guam wrote its last area forecast discussion before the first event at Oct 25, 9:17 AM UTC, 4 hours 43 minutes earlier.
Area forecast discussion, Oct 25, 9:17 AM UTC, 4 hours 43 minutes before
Area Forecast Discussion
National Weather Service Tiyan GU
717 PM ChST Mon Oct 25 2021
.Marianas Synopsis...
Partly cloudy skies with isolated showers and gentle winds prevail
across the Marianas this evening. Tropical Storm Malou is centered
west of the Marianas. ipan buoy shows seas near 3 feet while
altimetry shows seas of 5 to 7 feet across the region.
&&
.Discussion...
As TS Malou continues to move toward the north-northwest, a high
pressure ridge to the east of the system will dominate the pattern
across the Marianas. A small band of showers feeding into the main
feeder band into Malou is producing isolated showers across the
region tonight. The surface ridge will help dry out the region a bit
more by Tuesday morning, resulting in shower coverage dropping to a
slight chance through Wednesday. The ridge will begin to break down
over the last half of the week, wallowing increasing clouds and
showers Thursday, though coverage is expected to remain isolated. The
much needed drier pattern is expected to continue into the weekend,
when an approaching surface trough, currently east of 150E, will
approach the region. This will result in a 30 percent chance of
showers and thunderstorms late in the weekend into next week.
&&
.Marine...
As TS Malou continues to move toward the north-northwest, turning
toward the northeast by the end of the week, combined seas are
expected to remain between 4 and 6 feet. The primary swell will
initially be from the southwest, veering toward the west then
northwest. Seas are not expected to reach levels hazardous to small
craft nor produce hazardous surf conditions. However, the risk of
rip currents will be moderate along east and west facing reefs
through the week and along south facing reefs tonight. As the swell
becomes more northwest, the rip risk will decrease to low for south
facing reefs and increase to moderate along north facing reefs.
&&
.Tropical systems...
Tropical Storm Malou, 25W, is currently located northwest of Guam
near 19N138E, moving north at 18 mph. Malou will continue moving away
from the Marianas and is not expected to have any direct impact on
the Marianas or Micronesia. The main impact will be a west to
northwest swell produced by the storm later in the week as it becomes
more organized and symmetrical. For more information on TS Malou,
see bulletins issued by the Joint Typhoon Warning Center under WMO
header WTPN31 PGTW, and by the National Weather Service under WMO
header WTPQ31 PGUM.
&&
.Eastern Micronesia and Chuuk...
Light to gentle trade winds prevail across eastern Micronesia and
Chuuk. Drier conditions across the region through midweek, before
another trade-wind surge starts to make its way across the dateline
and bring scattered showers and isolated thunderstorms to Majuro on
Wednesday, to Kosrae on Friday, and to Chuuk sometime during the
weekend. The Hovmoller diagram indicates anomalous easterlies will
continue, with winds sometimes becoming breezy as multiple
disturbances make their way across.
For Majuro, seas will stay between 4 and 6 feet through tonight,
before dropping slightly through midweek and then increase to
between 5 and 7 feet before the next weekend. For Pohnpei and
Kosrae, seas will stay just under 3 to 4 feet for the rest of the
week before increasing slightly during the trade-wind surge. For
Chuuk, seas will be slightly benign, at just 3 to 4 feet through the
next weekend.
&&
.Western Micronesia for Palau and Yap...
A ridge is forming in the wake of Tropical Storm Malou as it is
making its way north, bringing isolated showers to Palau and Yap
tonight. Much of the mid- and upper-levels for both Palau and Yap
are considerably dry, providing little moisture to drive more
persistent showers at least through the middle of the week. As such,
just isolated showers expected. As trade winds return to bring
moisture from the east, shower and thunderstorm potential will
increase as well. As such, scattered showers and isolated
thunderstorms are expected by next weekend.
As TS Malou continues to consolidate, it is producing swell that
will affect sea heights for both Palau and Yap. Seas for Palau will
increase from 3 to 5 feet to between 5 and 6 feet by Thursday; for
Yap, seas will increase from 4 to 5 feet to between 5 and 6 feet by
Thursday as well. Model guidance is known for slightly under-
estimating north swell for the region, and as such, a slight
adjustment was made to account for this. As TS Malou continues to
develop and intensify, scatterometer data and altimetry will
continue to be observed for possible changes to the seas forecast.
&&
.GUM WATCHES/WARNINGS/ADVISORIES...
GU...None.
MP...None.
Marianas Waters...None.
&&
Marianas: Kleeschulte
Micronesia: Pavliukoit