Area Forecast Discussion
Issued by NWS Honolulu, HI

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694
FXHW60 PHFO 250658 CCA
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
840 PM HST Fri Feb 24 2017

.SYNOPSIS...
A surface ridge north of the area will maintain gentle to moderate
trade winds over the islands through the weekend. The atmosphere
will remain rather dry through Sunday morning, so rainfall will be
light. On Sunday, a trough will deepen northwest of the islands
while high pressure builds far to the northeast. The atmosphere will
become more moist and showers may become heavier through the first
half of next week. A ridge will build over the islands from the
northeast during the second half of next week bringing light winds
and dry, hazy weather.

&&

.DISCUSSION...
A surface ridge north of the area will maintain gentle to moderate
trade winds over the islands through Sunday morning. The atmosphere
will remain dry for the next 24 hours, so rainfall will be minimal
with only light windward showers.

Rainfall is likely to increase early next week as both moisture and
instability increase. As a trough deepens northwest of Kauai, the
atmosphere will become colder aloft which will bring increasing
instability. Meanwhile, the low level flow near the islands will
start to shift out of the southeast Saturday night. This will bring
moister air over the islands. Precipitable Water (PW) values will
steadily increase as this moisture streams in. Gentle southeast flow
will allow afternoon sea breezes to develop by Sunday. The unstable
atmosphere may allow afternoon showers to become heavy through the
first half of next week.

A surface ridge building over the islands during the second half of
next week will keep winds light. The atmosphere will stabilize as
the trough northwest of the area lifts north. Afternoon clouds may
continue, but rainfall is expected to become light. The light winds
may allow vog to become heavier over the smaller islands through the
second half of the week.

&&

.AVIATION...
There are no AIRMETs in effect and none are expected over the next
24 hours. VFR conditions will prevail, but moderate east northeast
winds may carry enough clouds and showers over windward areas to
produce brief MVFR ceilings.

&&

.MARINE...
A storm east of the Kamchatka peninsula produced a large long-period
northwest swell that has started rolling into the area. This swell
is expected to peak later tonight or Saturday before slowly
subsiding through Monday. A gale north of the area has produced a
smaller and shorter-period north swell. That swell is expected to
gradually shift out of the north northeast. These two swells will
combine to produce advisory level surf along north and west facing
shores of the smaller islands through Saturday night.

An east to west surface ridge near 25N will maintain gentle to
locally fresh trade winds through Saturday night. Winds will weaken
and shift out of the southeast Sunday as a trough deepens northwest
of the area. Winds will remain below Small Craft Advisory (SCA)
speeds for the next several days but the northwest and north swells
will produce seas above 10 feet over night. A SCA is in effect
through Saturday morning for these seas.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 6 AM HST Sunday for north and west facing
shores of Niihau, Kauai, Oahu and Molokai and north facing shores
of Maui.

Small Craft Advisory until 6 AM HST Saturday for waters around Kauai
and Oahu for large combined seas.

&&

$$
Donaldson



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