Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 250200

Area Forecast Discussion
National Weather Service Honolulu HI
400 PM HST Mon Oct 24 2016

High pressure north of the state will maintain moderate trade
winds through mid week. The trades will strengthen Thursday and
remain strong through the weekend. Showers will favor windward and
mountain areas with an increase in showers expected as the trade
winds increase.



High pressure far to the north is propelling island trade winds at
moderate speeds with breezy conditions throughout the state. An
old frontal band is bringing clouds and showers to windward areas
from the Big Island to Oahu this afternoon with some showers
reaching leeward locations. This band will sag to the south and
west through the night before clearing the area by tomorrow
morning. A similar frontal band will bring clouds and showers
Wednesday and Wednesday night as it passes from northeast to
southwest through the island chain.

The high pressure will maintain moderate trade winds through
midweek with limited showers focusing over windward and mountain
areas with passing leeward showers over the smaller islands. The
leeward Big Island will continue to see a diurnal pattern of
increasing afternoon clouds with scattered showers forming over
the slopes.

Trade winds will ramp up for the second half of the week as the
high pressure to the north strengthens and sinks south. Expect a
jump in the windspeeds between Wednesday and Thursday with breezy
conditions and strong gusts. Strong trades will continue through
the weekend as the high remains in place.

Upper level ridging will keep a cap on showers through Friday
afternoon with light to moderate rainfall amounts expected within
trade showers. An upper level trough is expected to push the ridge
to the south later on Friday and bring cooler temperatures aloft
over the islands. The cooler temps will increase instability and
allow for increased shower coverage and intensity Friday night and
into the weekend. With the strong trades and increasing cloud
growth, expect a wet trade wind regime over the weekend and into
next week.


Winds will ease slightly overnight into Tuesday. AIRMET TANGO for
low level turbulence over and immediately south through west of
the mountains will likely stay posted through the routine issuance
time, then be cancelled after 0400Z. However, pockets of isolated
turbulence will remain possible as a strong low level inversion
will remain. The 00z soundings showed the low level inversion
sloping from 8.0 at PHTO to 5.5 kft at PHLI.

Moisture from an old frontal band will continue to move through
the islands from Oahu to the Big Island, with conditions starting
to improve in the next few hours, mainly for Oahu through Maui.
AIRMET SIERRA for mountain obscuration is posted along north and
east slopes of Oahu, Molokai, Maui, and the Big Island. This will
be tailored as conditions improve.


The small craft advisory remains for the windier locations
between Molokai and the Big Island through Tuesday. High pressure
will build north of the state once again later in the week and
will result in a return of strong trades. Another period with
near gales in the windier marine zones and advisory-level surf
along east facing shores will become a possibility over the

Surf along east-facing shores will ease through Wednesday with
values remaining below advisory levels. A new long-period
northwest swell will fill in later tonight, peak late Tuesday
through Tuesday night, then gradually ease later Wednesday through
Friday. Surf heights will respond, but should remain well below
advisory levels through the peak. A small subsiding south swell
will remain into Tuesday translating to a slight bump in wave
heights along south facing shores.


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



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