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Hawaiian Islands Synoptic Discussion and Guidance

FXHW60 PHFO 210641

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

Trade wind weather prevails over the next several days with a
surface high pressure persisting far northeast of the area. Clouds
and passing showers will favor windward and mauka areas with most
leeward locations remaining dry. Winds may weaken late next week as
a front approaches the area from the northwest.


Trade wind weather continues across the islands this evening as a
high pressure far northeast of the area is providing locally breezy
trade winds to the area. Latest satellite imagery revealed patches
of low clouds have just reached the islands in the past few hours.
These clouds will be providing some passing showers to the area,
mainly over the windward and mauka areas. These showers are
generally on the light side as the airmass is rather stable due to
an upper ridge in place overhead. There are some high clouds passing
over the islands at time as well, and will keep the skies a little
more cloudy.

As only minor changes to the overall weather pattern are expected
into early next week, expect the current trade wind weather regime
to prevail. Passing low clouds and showers will affect mainly
windward and mauka areas. There will be a slight uptick in clouds
and showers during the night. But then, upper level ridging staying
nearby will keep the airmass on the stable side. Hence, showers will
be light. Most leeward locations will stay dry, though lee areas of
the Big Island will see some afternoon and evening showers.

Latest forecast solutions still indicated there will be changes in
the weather for the islands toward late next week, as an upper low
and its associated surface frontal boundary are still expected to
approach the area from the northwest. This will nudge a surface
ridge closer to the state, leading to winds becoming lighter across
the area. Daytime sea breezes and nighttime land breezes will likely
become more widespread. Clouds and showers under this weather
scenario will tend to favor interior and mauka areas during the
afternoon and evening hours.

A ridge of high pressure north of the state will keep moderate to
breezy trade winds in place through Sunday. Clouds and showers will
favor windward and mauka areas, bringing brief MVFR cigs/vsbys as
they move through. A few showers may spill over into leeward areas
occasionally, but VFR conditions are expected to prevail here.

AIRMET Tango remains in effect for moderate turbulence below 080
over and downwind of the terrain. This AIRMET will likely remain in
effect through the remainder of the weekend.

AIRMET Sierra may be needed for mountain obscuration later tonight.


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 is in effect through
Monday, but will likely need to be extended till around midweek.

Surf along all shores is expected to remain below advisory levels
for the next week. The current north-northwest swell fade out
tonight with only background swell expected for Sunday. A small
west-northwest swell will provide small surf along north facing
shores 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 hold
steady into the middle of next week due to the fresh to locally
strong trades.


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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