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000
FXPQ60 PGUM 272151
AFDPQ

Area Forecast Discussion
National Weather Service Tiyan GU
751 AM CHST SAT MAY 28 2016

.Synopsis...
PGUA Doppler weather radar shows isolated showers within the
Marianas waters. Drier weather with almost no showers is seen
east of the coastal waters. Gradually this drier weather is
filtering into the Marianas. The VAD wind profile reveals East-
southeast winds of 4 to 8 knots through the lowest 3 thousand feet
of the air. The weather balloon from Friday evening indicates that
winds shift toward the Northeast above 5 thousand feet then toward
the Northwest above 20 thousand feet.

&&

.Discussion...
GFS and ECMWF-HiRes still show a surface ridge sagging southward
over the Marianas and surrounding waters. This will tend to keep
the weather relatively dry and the winds light. The light winds
seem like they might promote island convection, however moisture
is limited so did not write that into the forecast. The expected
dry weather and light winds resulting in low combined seas will
create benign conditions in most forecasts. The principal
exception will be fire weather, highlighted below. This general
pattern is expected to persist for at least next week.

&&

.Fire weather...
While the light winds will preclude a fire weather watch or red
flag warning, that is where the good news ends for fire weather.
Low afternoon relative humidities and dry fuels will generate
otherwise ideal conditions for spread of grass fires especially.
The Keetch-Byram drought index has risen to 790 this morning out
of a possible 800. The only 2 years it has reached values higher
than this were 792 in 1983 and 797 in 1987. If the models verify
in their forecasts of no wetting rains next week the KBDI will
reach that 792 on Tuesday and make it to 797 next Saturday.

&&

.Eastern Micronesia...
A few showers are seen south of Pohnpei while a wider swath of
showers and thunderstorms is seen over portions of the northern
Marshalls extending southeastward to the east of Majuro. Wet weather
will spread over Majuro tonight and linger through Sunday night
before moving westward. Kosrae will see isolated showers and
thunderstorms by Sunday night. Models show the zone of trade-wind
convergence centered near Kosrae but the shower coverage is a little
more diffuse by Sunday. Similarly, Pohnpei will see increasing
cloudiness and a slight chance of thunderstorms early next week as
the trade disturbance continues westward.

&&

.Western Micronesia...
Quiet weather conditions persist across much of the region with
some showers seen south and southeast of Yap and Koror and farther
southeast of Chuuk. The subtropical ridge remains just north of
Yap over the Philippine Sea and an upper-level trough curves
northeastward from Yap toward the Marianas. Divergence aloft is
helping to trigger short-lived thunderstorms in the area but
convection is, at best, isolated. With no large scale features
expected to develop across the area, few changes were needed to
the inherited forecast. Light winds at Koror could set the stage
for afternoon thunderstorms the next day or two.

&&

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

$$

Stanko/W. Aydlett





000
FXPQ60 PGUM 270553
AFDPQ

Area Forecast Discussion
National Weather Service Tiyan GU
353 PM CHST FRI MAY 27 2016

.Synopsis...
Gentle winds and partly cloudy skies are found across the Marianas
this afternoon. Radar and satellite show isolated light showers...
mainly east of the islands.

&&

.Discussion...
In this dry static weather pattern characterized by a surface
ridge across the Marianas...there was no reason to change the
forecast. Isolated showers still look good through Sunday...but
then only a slight chance of showers is seen for next week.

&&

.Fire weather...
Winds are expected to be gentle for the next week or so...and as a
result there should be no red flag conditions. Even so...with such
dry conditions in place outdoor burning would not be a good idea
until rain returns to the region.

&&

.Eastern Micronesia...
Satellite imagery shows a trade-wind disturbance passing by south of
Pohnpei this evening while drier weather is seen at Majuro and
Kosrae. Most showers will keep south of Pohnpei overnight...but
skies will be mostly cloudy. Another trade-wind disturbance just
east of Majuro will bring more clouds and possibly a thunderstorm or
two to the central Marshall Islands over the weekend. Dry weather
will prevail at Kosrae and Pohnpei through the weekend. Another
trade-wind convergence pattern is progged to develop from east to
west by Sunday night and could bring an increase in clouds and
showers to the region next week.

&&

.Western Micronesia...
A trade-wind disturbance southeast of Koror will head west overnight
bringing isolated showers and thunderstorms to the Republic tonight.
Drier weather will persist at Yap and Chuuk overnight. Another
disturbance south of Pohnpei will head west and bring isolated
showers and thunderstorms to Chuuk for the weekend. Weak ridging
this weekend will keep dry and pleasant conditions in place at Yap
and Koror. Did maintain a slight chance of thunderstorms for Koror
for the afternoon time in case there is enough moisture to support
island-effect convection.

&&

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

&&

$$

Middlebrooke/M. Aydlett





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