Current Conditions
Temp7.5 C
RH23 %
WindWNW 3 mph
RoadOpen (4x4)
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Hawaiian Islands Synoptic Discussion and Guidance

238
FXHW60 PHFO 152022
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
1022 AM HST Thu Nov 15 2018

.SYNOPSIS...
A trough over the islands will dissipate by this evening as a high
builds north of the area. The trailing end of a frontal band will
move over the islands from the north on Saturday. The band will
move south of the Big Island Sunday night. The trailing end of
another front may move over the islands during the middle of next
week.

&&

.DISCUSSION...
Surface analyses show a weak trough extending north from over the
islands. The trough has been producing light winds over the
islands. High clouds are moving over the area from the west but
land breezes have cleared away the low clouds over the islands
bringing dry weather this morning. Winds may remain light enough
for afternoon cloudiness to develop and produce a few showers over
interior areas this afternoon.

A 1027 mb surface high is centered about 1100 miles northwest of
Kauai near 35N 171W. This high will move east over the next few
days and bring a return of breezy trade winds by tonight. The high
will push a band of showery low clouds...the trailing end of a
front...southeastward toward the islands. The shower band will
reach Kauai late tomorrow night then push southeast across the
area moving southeast of the Big Island Sunday night. There will
be frequent showers over windward areas as the band passes with
scattered showers over leeward areas. A trough aloft is forecast
to dig south toward the area, but the global models have backed
way off on the moisture and instability associated with the
trough. I have dropped thunderstorms and heavy rain from the
forecasts.

The high will gradually weaken early next week as a new front
approaches from the northwest. A strong new high will build behind
the front. The trailing end of the front will likely move over the
islands during the middle of next week and produce more wet weather
over windward areas.

&&

.AVIATION...
Light winds this morning will gradually give way to strengthening
northeast trade winds this afternoon. A relatively dry and stable
airmass over the state currently will begin to destabilize today
as a mid-level trough pushes in from the northwest. The more
unstable atmosphere combined with increasing trade winds will
cause showers to become more frequent over windward sections, with
areas of MVFR conditions and mountain obscuration possible,
especially later today and tonight. AIRMET SIERRA may be required
for mountain obscuration at that time. There will also be a slight
chance of thunderstorms over at least windward sections of the
state beginning this evening.

&&

.MARINE...
Light trade winds over the area will gradually increase later
today and tonight as high pressure builds far north of the state.
Winds will become strong enough likely requiring a Small Craft
Advisory over the typically windy waters around Maui County and
the Big Island. These strong winds are expected to continue
into early next week. A new northwest swell filling in tonight
and Friday may cause seas to exceed the 10 foot advisory threshold
over exposed waters around Kauai and Oahu.

The northwest swell is expected to arrive tonight, peak on Friday,
then lower gradually Friday night and Saturday. A slightly
smaller north northwest swell is expected Saturday night and
Sunday. Another small to moderate size northwest swell is expected
to arrive on Monday, peak Monday night and early Tuesday, then
lower gradually into Wednesday. Small, mainly background south
swells are expected through the remainder of this week and on into
the middle of next week. A slight uptick in short period choppy
surf can be expected beginning Friday as the trade winds increase.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$
DISCUSSION...Donaldson
AVIATION...Foster
MARINE...Burke

Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office