Current Conditions
Temp5.2 C
RH19 %
WindNE 18 mph
RoadOpen (4x4)
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Hawaiian Islands Synoptic Discussion and Guidance

FXHW60 PHFO 241315

Area Forecast Discussion
National Weather Service Honolulu HI
315 AM HST Mon Oct 24 2016

High pressure north of the state will keep a moderate to locally
breezy trade wind flow in place through mid week. The trades will
strengthen late in the week and next weekend as another strong
high builds north of the island chain. Bands of enhanced moisture
will occasionally move through the area, increasing shower
activity particularly over windward and mauka locales.


Currently at the surface, a 1025 mb high is centered around 925
miles northwest of Kauai, and is driving the moderate to locally
breezy trade winds across the area early this morning. Infrared
satellite imagery shows partly to mostly cloudy skies in place,
with some enhanced cloud cover over windward areas, as well as
some cirrus streaming over the eastern half of the state.
Meanwhile, radar imagery shows scattered showers moving into
windward areas, with the occasional shower spilling over into
leeward portions of the smaller islands. Main short term concern
for the next several days revolves around rain chances.

Today through Wednesday night,
High pressure to the northwest of the state will weaken slightly
through mid week, but the gradient will remain strong enough over
the islands to keep moderate to locally breezy trade winds in
place. A series of enhanced moisture bands or old frontal
remnants will periodically move through the area, increasing
shower activity mainly over windward and mauka locales. One band
of moisture will shift southward through Maui County and the Big
Island on today, followed by another band sinking southward and
mainly affecting Kauai tonight and Tuesday. A better defined
moisture band will then shift southward through the islands
Wednesday and Wednesday night as strong high pressure begins to
build north of the area. Precipitable water (PW) values through
the period will remain near to below normal, and with upper
ridging keeping conditions stable, rainfall amounts are expected
to remain light.

Thursday through next Sunday,
The trades will strengthen to breezy and locally windy levels
late in the week and through the weekend as strong high pressure
builds to the north of the Aloha state. Upper level troughing
will begin to shift southward toward the area Thursday night and
Friday, with the troughing lingering over the islands through
much of next weekend. The more unstable conditions associated
with the troughing aloft, along with PW values rising to above
normal levels, should result in periods of wet trade wind
weather. Showers will favor windward and mauka areas, but the
showers will reach leeward areas more frequently due to the
elevated moisture levels, more unstable conditions and strong


Gusty trade winds will slowly ease today and tonight. AIRMET
TANGO for moderate low level turbulence over and immediately
south through west of the mountains remains in effect. The trade
winds will continue to focus clouds and showers along the windward
slopes. Isolated MVFR conditions will be possible in these areas.
VFR conditions will prevail elsewhere.


The overnight ASCAT pass that came in around midnight showed 20 to
30 knot trade winds over the Hawaiian waters. The highest winds were
located over the typically windier locations between Molokai and the
Big Island and south of Oahu. The latest numerical guidance has
initialized well with the current pattern and generally depicts a
downward trend today through Tuesday. As a result, the small craft
advisory will be updated to only include these windier locations
between Molokai and the Big Island today 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
gales in the windier marine zones and advisory-level surf along east
facing shores will become a possibility over the weekend.

The latest CDIP/PacIOOS nearshore buoy observations exposed to the
strong trades have also begun to show a downward trend over the past
several hours and all remain below the 10 ft advisory-level. That
trend will continue through Tuesday. The surf along east-facing
shores will respond and steadily ease through this time 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 south
swell has recently begun to fill in at the Lanai buoy, which should
translate to a slight increase in surf along south facing shores
today through Tuesday before fading through the mid-week period.


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




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