Weather Service Report


267 
FXHW60 PHFO 272006
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
1006 AM HST Mon Mar 27 2017

.SYNOPSIS...
A ridge will remain north of the state through Thursday night and
will drive moderate east to southeast flow across the state. A
trough aloft will dig east of the island chain Tuesday night and
will bring more windward showers to the state during the second
half of the work week. A prefrontal band of showers may impact the
state Thursday night and Friday, but the front is not expected to
reach the state. A strong high will set up northeast of the state
this weekend and bring windy conditions.

&&

.DISCUSSION...
A 1031 mb surface high lies about 1750 miles northeast of
Honolulu, with a surface ridge extending southwest from the high
and passing 375 miles north of Honolulu. The ridge will remain
nearly in place through Thursday night and drive moderate east to
east southeast flow across the state through then.

A ridge aloft will remain over the main Hawaiian islands through
tomorrow night. The ridge will keep the atmosphere dry and stable,
so rainfall will remain light until then. Models show an increase
in precipitation arriving early Wednesday morning as an upper
trough digs in east of the state on Tuesday night. The trough
will enhance the moisture tracking in from upstream and will bring
relatively wetter trade wind weather during the second half of the
week. Winds will focus most of the precipitation over windward
and southeast facing slopes. Leeward areas may see a few passing
showers at times.

The ridge to our north will slide to the east Thursday night as a
cold front approaches from the west. The front will stall out
Friday night and a building high to the north over us will force
the front away from us before impact. However, a prefrontal band
of showers will form out of the lingering moisture brought in with
the trade winds and set up over the state Thursday night and
Friday.

The aforementioned high pressure system to the north is forecast
to strengthen to about 1038 mb this weekend. Subtropical highs at
this strength typically produce some windy conditions for us. The
atmosphere will stabilize this weekend with typical windward and
mauka showers moving in with the trades.


&&

.AVIATION...
A stable trade wind flow will produce isolated MVFR ceilings
along windward terrain. VFR will dominate elsewhere. An inversion
will remain in place between 5000 to 7000 ft with moderate E to SE
winds up to 20 kt at low levels. No AIRMETs in effect.


&&

.MARINE...
The current west-northwest swell continues to bring advisory
level surf to various north and west facing shores exposed to the
swell. In addition, resulting seas in excess of 10 ft are
contributing to a Small Craft Advisory (SCA) for most coastal
waters. The swell is expected to slowly ease into tomorrow, and
then hold steady into Wednesday as a slight reinforcement arrives. 

In addition to the elevated seas, winds remain elevated in the
typically windier locations near Maui and the Big Island. Winds
will slowly drop below SCA levels mid week.

Surf along east facing shores will remain small and choppy
through the week due to moderate trade winds. The above mentioned
west-northwest swell is wrapping around the islands and is aiding
a small south-southwest long period swell is bumping surf along
south facing shores. A long period south swell is expected to
bring a bump to south facing shores again Thursday through
Saturday.

A new, potentially larger, west northwest swell is expected to arrive
Thursday night, peak Friday and then slowly ease over the weekend.
The swell is being generated by a strong low off the coast of
Japan with hurricane force winds. Will be monitoring model runs as
the system evolves.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 600 PM HST today for north and west
facing shores of Niihau, Kauai, Oahu and Molokai, north facing
shores of Maui, and west facing shores of the Big Island.

Small Craft Advisory through 600 PM HST today for all Hawaiian
waters except Oahu leeward waters and Maalaea Bay.

&&

$$

DISCUSSION...Foster
AVIATION...Wroe
MARINE...M Ballard

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