Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 170721

Area Forecast Discussion
National Weather Service Honolulu HI
921 PM HST Fri Mar 16 2018

Trade winds will be making a short visit over the weekend. A bit
more comfortable weather will accompany this change in airmass.
Another wet period is possible next week as a cold front stalls
west of Kauai, causing a shift in the winds to the southeast,
which will bring a rise in the humidity, vog, and increasing
chance for showers.


It is a rather quiet evening with light winds and relatively fair
skies, especially across the smaller islands. There are still
some leftover afternoon clouds over these islands, but do expect
them to clear out as a land breeze develops in the coming hours.
The Big Island is under a trade wind flow. We do anticipate a rise
in trade showers, especially after midnight.

The trades will be expanding west to the smaller islands
Saturday, although it looks light enough to bring on sea breezes
across the leeward shores during the morning hours. This will lead
to some spotty afternoon clouds and or showers there. In essence,
we are looking at a hybrid, a mix of trades and sea breeze. By
late afternoon, we expect the trades to expand into the lee areas,
chasing out any showers that may have developed.

Later on Saturday night, the trailing band of clouds and showers
descend on the islands from the north, reaching Kauai shortly
after midnight, Oahu around sunrise, Maui county in the afternoon,
and the Big Island Sunday evening. The remnant moisture from this
band will be slow to clear the Big Island, with showery
conditions lasting into Monday. Moderate trades settles in behind
this band, with some scattered showers favoring the windward and
mountain areas.

This trade pattern is expected to hold through Monday. An
approaching front will cause a shift in the winds to the southeast
starting Monday afternoon, especially the west end of the island
chain. From about Tuesday or Wednesday on, the showers become more
active. The source of the showers, is from the remnants from the
band that had moved through a couple of days earlier. The GFS
solution is more vigorous with showers statewide, aided by a deep
trough. The old ECMWF, keeps the showers to the western half of
the island chain. Dense high clouds will fill the island skies
once more, as early as Sunday night. We will fine tune the
forecast as models come into better agreement.


Predominant VFR conditions tonight with maybe the exception of
PHTO and southern sections of the Big Island Maui Molokai and
Lanai possibly having isolated MVFR conditions while the southerly
breeze is still in place. With that being said land breezes are
expected in most locations overnight. Trade winds will gradually
work back into place through the day Saturday. When that happens
we will expect to see the return of isolated MVFR condition along
the windward slopes as clouds build and some lead to showers.


No marine warnings are expected for the next few days. After trade
winds return by Saturday afternoon and evening, a moderate wind
regime is expected to persist into Tuesday. Small Craft Advisory-
level winds may return through the channels around the Big Island
and Maui County Sunday and Monday. Winds will begin to shift
towards the southeast once again late Tuesday through the second
half of the upcoming week as a front approaches from the west and
stalls, likely bringing another wet period with heavy showers back
across the coastal waters.

A series of small northwest swells will begin filling in tonight.
Surf will remain well below advisory levels with these swells over
the next several days.

A broad low is forecast to develop and move into the northeast
Pacific late this weekend and direct a large swath of gale force
winds towards the islands. This should translate to a building
north-northeast swell late Tuesday. This could bring advisory
level surf to north and east facing shores.

Small long period south swells should provide above null surf for
the south facing shores over the next few days.





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