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Temp1.3 C
RH26 %
WindNE 15 mph
RoadOpen (4x4)
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Hawaiian Islands Synoptic Discussion and Guidance

385
FXHW60 PHFO 050634
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
834 PM HST Thu Jun 4 2020

.SYNOPSIS...
Breezy trade winds will ease somewhat over the weekend, delivering
periods of clouds and showers that will primarily dampen windward
and mauka areas.

&&

.DISCUSSION...
Breezy trade winds will prevail over the islands for the foreseeable
future, but a front passing N of the islands Saturday into Monday
will lead to some weakening and veering of the winds, most notable
over the W end of the island chain.

The trade winds will deliver occasional clusters of low clouds and
showers through the period, primarily dampening windward areas.
While confidence in picking out drier vs wetter periods with a
prevailing trade wind flow is relatively low, current thinking is
that an area of showery low clouds will traverse the smaller islands
overnight before a decrease in PWAT on Friday results in fewer
windward showers. Model guidance alludes to an increase in PWAT and
a developing 700 mb trough over the weekend that will likely fuel
another increase in windward showers. The lighter winds could allow
a few leeward clouds and showers to develop over the smaller islands
in the afternoons in response to localized sea breeze convergence.
Leeward Big Island can depend on afternoon clouds and showers that
sometimes linger well into the early morning hours.

Longer range guidance indicates breezy to windy trade winds by the
middle of next week.

&&

.AVIATION...
A high pressure cell to the northeast of the state will bring
moderate to breezy trades across the islands tonight. Sufficient
moisture in the lower levels will allow for scattered showers
along the windward sides, especially along the elevated terrain.
MVFR conditions are likely to be associated with this activity
and bring lowered ceilings and visibility.

AIRMET TANGO remains in effect below 8000 feet south through west
of mountains due to tempo moderate turbulence.

&&

.MARINE...
Fresh to strong trade winds will likely continue through the
weekend over the eastern end of the state (may require an
extension to the Small Craft Advisory for the windy areas).
Guidance shows a weakness in the ridge developing due to a passing
front far north of the area Sunday into Monday, which could be
enough for the trades to trend down into the moderate category
over the western end. Trades will surge back into the strong
category statewide by Wednesday as 1030 mb high pressure sets up
north of the state.

Surf along south facing shores will steadily trend down overnight
into Friday (likely below the advisory level Friday), but hold
steady around the summer average through the weekend as another
long-period pulse fills in by Saturday. This will continue
through Sunday, then lower into early next week. A small southwest
swell is expected by Wednesday of next week from recent activity
across the Tasman Sea. Surf will respond and rise, but should
remain below advisory levels from this source.

Surf along east facing shores will remain small and choppy with
the moderate to fresh trades locally and upstream across the
eastern Pacific.

Surf along north facing shores will trend down Friday - likely
becoming flat for most beaches. Guidance shows this continuing
into next week.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 6 AM HST Friday for South facing shores of
all islands.

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

&&

$$

DISCUSSION...Birchard
AVIATION...Thomas
MARINE...Gibbs

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