Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 190627
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
827 PM HST Thu Apr 18 2019

.SYNOPSIS...
A ridge of high pressure north of the state will keep moderate to
locally breezy trade winds in place through late next week. Fairly
dry trade wind weather will prevail through the period, with
clouds and showers limited primarily to windward and mauka areas.

&&

.DISCUSSION...
Currently at the surface, a 1029 mb high is centered around 1350
miles north-northeast of Honolulu, with a surface ridge extending
southwestward to a location around 350 miles north of Kauai. The
resulting pressure gradient is driving moderate trade winds across
the island chain this evening. Infrared satellite imagery shows
clear to partly cloudy skies in place in most areas, with cloud
cover most prevalent in windward areas. Radar imagery shows a few
showers moving into windward areas, with generally dry conditions
in leeward locales. Main short term focus revolves around rain
chances.

A ridge of high pressure will prevail to the north of the state
through late next week, keeping the trade winds blowing across the
island chain. There could be a slight increase in trades over the
weekend as the surface ridge axis lifts a bit further northward,
but generally moderate to locally breezy trades should prevail.
Upper level ridging will keep the airmass stable with rather dry
conditions expected with precipitable water values remaining at or
below seasonal levels. As a result, expect fairly dry trade wind
weather to prevail through the period, with showers confined
primarily to windward and mauka areas. Leeward areas should remain
dry most of the time, with isolated showers confined mainly to the
overnight and early morning hours.

&&

.AVIATION...
A high pressure ridge north of the state will keep the islands in
a moderate to breezy trade wind weather pattern into the weekend.
Near surface wind speeds are strong enough to support moderate
low level turbulence over and south through west of mountain
ranges of all islands. Scattered shower activity will favor
windward and mountain sections with brief periods of MVFR
conditions mainly during the overnight hours.

AIRMET Tango remains in effect for tempo moderate turbulence below
080. This AIRMET will likely remain in effect through the
weekend.

&&

.MARINE...
A ridge north of the islands will maintain fresh to strong trade
winds through early next week. A Small Craft Advisory (SCA)
remains posted for the typical windier areas near Maui County and
the Big Island. With confidence high that these conditions will
continue, the SCA is out through Sunday afternoon. Most likely the
SCA will be extended, with the trades expected to continue into
the new work week.

A small, north-northwest swell will build tonight, and peak below
advisory levels Friday, before slowly declining through the
weekend. A small, west-northwest swell from a compact gale that
has developed east of Japan will be possible early next week,
again expected below advisory levels.

Background south-southwest swells will keep small surf along south
facing shores through the weekend. An upward trend is expected early
next week, as early as Sunday night, due to activity south to
southeast of New Zealand over the past few days. Guidance depicts
this source peaking at Pago Pago Saturday, which should correlate
to above average south shore surf continuing into midweek.

Expect surf along east facing shores to rise a little on Friday
and on through the weekend due to the trades.

See the latest Oahu Surf Discussion (SRDHFO) for additional
details on surf and swell.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 PM HST Sunday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.

&&

$$

DISCUSSION...Jelsema
AVIATION...Bohlin
MARINE...M Ballard


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