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Hawaiian Islands Synoptic Discussion and Guidance

FXHW60 PHFO 210201

Area Forecast Discussion
National Weather Service Honolulu HI
401 PM HST Sat Apr 20 2019

A trade wind weather pattern will be in place over the next
several days thanks to high pressure north of the area. Clouds and
passing showers will favor windward and mauka areas with most
leeward locations remaining dry. Winds may weaken later next week
as a front approaches the area from the northwest.


High pressure is centered far northeast of the area with a ridge
extending west southwest from the highs center to position several
hundred miles north of the state. This places the islands in a
moderate trade wind environment. Moisture embedded in the trades
is providing for some passing light showers over some windward and
mauka areas but these showers are generally on the light side as
the airmass is rather stable due to an upper ridge in place

The surface high will remain northeast of the area over the next
couple of days while a new high passes by far north of the area
Wednesday and Thursday. This will keep the islands in a moderate
trade wind environment. Upper level ridging will remain nearby
keeping the airmass on the stable side. Thus light showers will
continue to favor windward and mauka areas while most leeward
locations will remain dry.

As we get later in the week, an upper low and its associated
surface frontal boundary will be approaching the area from the
northwest. This will nudge the surface ridge closer to the state
with winds becoming lighter as a result. Daytime sea breezes and
nighttime land breezes will likely develop. Clouds and showers
under this regime will tend to favor interior and mauka areas
during the afternoon and evening hours.


A ridge north of the state will maintain a moderate to breezy
trade wind weather pattern through Monday. Winds are strong
enough to generate moderate low level turbulence over and south
through west of mountain ranges of all islands. Scattered showers
will favor windward and mountain sections, with brief periods of
MVFR conditions expected mainly during overnight and morning

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


The ridge to the north of the islands will maintain fresh to strong
trade winds into early next week. The Small Craft Advisory (SCA)
is in effect for most of the waters near Maui County and the Big
Island now through Sunday, before winds ease slightly and a few
zones drop out. The SCA for the more typical windy areas has been
extended through Monday.

Surf along all shores is expected to remain below advisory levels
for the next week. The current north-northwest swell will continue
to decline through the weekend, with a small, west-northwest swell
possible early next week. Background south-southwest swells will
keep surf small along south facing shores through the weekend, though
an upward trend is possible early next week, due to recent activity
southeast of New Zealand. Surf along east facing shores will see a
bump this weekend in response to the increased trade winds. See
the latest Oahu Surf Discussion (SRDHFO) for additional details on
the surf and swells.


Small Craft Advisory until 6 PM HST Monday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.

Small Craft Advisory until 6 PM HST Sunday for Kaiwi Channel-
Maui County Windward Waters-Big Island Windward Waters.




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

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It was last modified on: Wed, Dec 17 2014 - 1841 UTC
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