Area Forecast Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
000
FXPQ60 PGUM 162214
AFDPQ

Area Forecast Discussion
National Weather Service Tiyan GU
402 AM ChST Tue Oct 17 2017

.Marianas Synopsis...
Andersen Air Force Base Doppler weather radar shows occasional
showers with isolated thunderstorms in the Guam and Rota waters,
with isolated showers and thunderstorms in the Tinian and Saipan
waters. The buoys indicate combined seas of 5 to 7 feet. The VAD
wind profile reveals southwest winds of around 5 knots through the
lowest 11 thousand feet which then turn to the northwest above
that and increase to 10 to 20 knots.

&&

.Discussion...
Weak circulation is moving through the Marianas, almost right over
Guam right now. The circulation along with the whole monsoon
trough will continue to progress northward. This will bring the
west winds to Rota in the next few hours and Tinian and Saipan
around Wednesday. Lots of showers in the Guam and Rota waters
today. So far they have been hit and miss, and more miss than hit.
This is convective minimum though, and with this many showers
around and the models dumping copious amounts of QPF on us, they
should come around. Ridging will invade the zones around Thursday
to Friday, drying out the weather. We are currently retaining the
thunderstorms in case the upper-level trough sticks around. We
will re-evaluate that once the ridge sets in.

&&

.Marine...
Winds should remain fairly benign, however seas will rise markedly
between swell from Tropical Storm Lan and the southwest monsoon
winds flowing into it. We are expecting small craft and high surf
advisories due to seas and waves starting Thursday.

&&

.Tropical systems...
Tropical Storm Lan is moving west still, it is expected to turn
north in the next 24 hours. It is slowing down now and this is
often what happens just before they turn. It is expected to
intensify and could become a typhoon Wednesday. The current track
threads it between the Marianas and the Philippines, so for the
next few days not many people are threatened by it right now.

&&

.Eastern Micronesia and Chuuk...
A surface trough continues to generate scattered showers and a few
thunderstorms across Kosrae State this morning. Similar weather is
seen across the Marshall Islands within a convergent southeast
wind flow. Drier conditions at Pohnpei and Chuuk this morning will
persist with light southeast winds becoming variable at times the
next couple days. Showers and thunderstorms will persist near
Kosrae and Majuro the next couple days as an ITCZ feature tries to
develop east of the trough at Kosrae. Another trough/weak
monsoonal-type trough will try to develop late in the week. GFS
shows this around Saturday, which could affect wind direction and
shower expectations.

Wave models show a building northeast swell later in the week that
may cause some minor coastal inundation along north and east
facing reefs of Majuro. The swell is expected to build to around 6
ft so hazardous surf is not expected at this time.

&&

.Western Micronesia...
Tropical Storm Lan continues to strengthen this morning but is
also pulling away from Yap and Koror. However, the strong monsoon
flow southwest of TS Lan will maintain fresh to strong south to
southwest winds and wet weather at least through tonight at both
locations. Gusty winds and locally heavy rainfall are expected
through tonight. Models still show rain and thunderstorms
tapering off Wednesday or Wednesday night as TS Lan moves
northward in the Philippine Sea. Southwest winds of 20 to 25 kt
will gradually subside late in the week.

Small Craft Advisories remain in effect for both Yap and Palau for
winds and seas. Also, surf will remain hazardous along south and
west facing reefs and beaches at Koror and Yap. As TS Lan moves
away slowly, a long-period northwest swell will reach the area,
prolonging hazardous surf along west reefs, and possibly extending
it around to north reefs.

&&

.GUM WATCHES/WARNINGS/ADVISORIES...
GU...None.
Marianas Waters...Small Craft Advisory for winds until 6 AM CHST early this
     morning for PMZ153-154.

&&

$$

Stanko/M. Aydlett



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.