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
798
FXPQ60 PGUM 262201
AFDPQ

Area Forecast Discussion
National Weather Service Tiyan GU
801 AM CHST FRI MAY 27 2016

.Synopsis...
PGUA Doppler weather radar shows scattered showers and isolated
thunderstorms west of the Marianas waters, moving west, and
isolated showers and thunderstorms southeast of the Marianas
waters, moving west. Within the coastal waters mainly dry
conditions prevail, which is expected to continue as both groups
of showers seem likely to miss the forecast zones. The VAD wind
profile reveals east-southeast winds of 8 to 14 knots through the
lowest 4 thousand feet of the air. Last night`s weather ballon
showed the winds changing toward the northeast above 10 thousand
feet and toward the northwest above 20 thousand feet.

&&

.Discussion...
Both the GFS and the ECMWF-HiRes show the subtropical ridge
sinking anomalously far south for this time of year. This will act
to keep the weather even drier than usual for a post-peak El Nino
drought during dry season. Under light to gentle winds, seas will
remain 2 to 4 feet through next week unless they subside farther
to between 1 and 3 feet. All conditions are benign with the
exception of fire weather.

&&

.Fire weather...
Light to gentle winds are going to be the only criterion missing
from a red flag event. That is enough to prevent the issuance of a
watch or warning though. Even so, low afternoon RH and dry fuels
will make for a potentially volatile mix. The Keetch-Byram drought
index has now risen to 789 at the weather office. The only higher
peaks are 792 in 1983 and 797 in 1987. Both the ECMWF-HiRes and
the GFS keep Guam pretty dry over the next 10 days, which should
allow it to rise more.

&&

.Eastern Micronesia...
Satellite imagery shows a trade-wind disturbance passing by south of
Pohnpei and drier conditions settling in to the area over Kosrae and
the Marshalls. There is a small chance of thunderstorms this
afternoon through Saturday at Pohnpei, but the bulk of showers and
thunderstorms will stay well south of the area. Dry weather will
persist across the area through Saturday but then models show
another trade-wind convergence pattern developing from east to west
by Sunday. This will bring increasing clouds and a better chance of
showers to most locations from Sunday into early next week.

&&

.Western Micronesia...
Sporadic showers and a couple of small thunderstorms are seen across
the area, mainly across portions of Yap State, but a broader trade-
wind disturbance is seen east of Koror. Dry and mostly sunny
conditions at Koror this morning will gradually become cloudier with
some showers and thunderstorms as the bulk of the disturbance
passes to the south.  Although drier weather is expected at both
Yap and Koror in the long term as the subtropical ridge axis drops
south...weak surface winds may allow some thunderstorms to develop
during at Koror later in the weekend. Chuuk will see some clouds
building in from the southeast later in the weekend as the trade-
wind disturbance near Pohnpei approaches.

&&

.GUM Watches/Warnings/Advisories...
GU...None.
Marianas Waters...None.
&&

$$

Stanko/W. Aydlett



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