Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 281957

Area Forecast Discussion
National Weather Service Honolulu HI
957 AM HST Fri Oct 28 2016

A breezy trade wind pattern can be expected over the next several
thanks to an area of high pressure north of the state. Clouds and
passing showers will tend to favor windward and mauka areas with
the trade winds sufficiently strong enough to blow some low clouds
over to leeward areas at times. An upper trough will move over the
area this weekend with an uptick in shower activity expected.
Drier and less breezy weather is expected to return by the middle
of next week.


Mainly light passing showers can be expected today over windward
and mauka areas with just a few light showers expected over some
leeward locations. Some passing high clouds can also be expected
at times.


.PREVIOUS DISCUSSION (Issued at 4 AM HST Friday)...
Locally breezy trade wind weather continues across the state
early this morning, as strong high pressure stays far north of
the state. Early morning Lihue and Hilo soundings continue to
display a stable trade wind weather type profile, though low level
moisture now extends to near 10 thousand feet on the Hilo
sounding. Latest satellite imagery revealed a band of low clouds
reaching the windward areas of islands at this time, bringing some
showers. Furthermore, there are more areas of low clouds just east
of the islands. These areas of low clouds carried by the trades
will reach the state throughout the day, bringing showers to the
area. High clouds in the island vicinity has cleared quite a bit
overnight, though there are more high clouds further west-
southwest of the area. These high clouds will eventually pass by
the islands under the upper level westerly wind flow, keeping
skies a little more cloudy at times later today. Thus, look for
breezy trade wind weather to prevail today, with passing showers
affecting mainly the windward and mountain areas. Some showers
will reach the lee areas of the smaller islands as well under the
brisk winds.

The high far north will move southeast and weaken slightly in the
next couple of days. However, pressure gradient across the area
remains rather tight. Hence, winds stay rather strong through the
weekend. Airmass in the island vicinity will remain somewhat stable
today but will become more unstable Saturday through Monday as an
upper trough is forecast to deepen and move across the state.
Cooling mid-level temperatures associated with the trough will lead
to the erosion of the inversion, allowing the airmass to become more
unstable. Showers will become more active over the weekend into
early next week, with heavier rainfall possible. On the other hand,
breezy trade winds will keep the showers moving rather swiftly,
possibly limiting the amounts for any one location. Expect wet and
breezy trade wind weather for the islands over the weekend into
early next week.

The overall synoptic weather pattern over the north Pacific is
rather progressive through next week, with fronts and high pressure
systems passing north of the state at times. Forecast solutions are
in fair agreement, with a ridge of high pressure eventually settling
to just north of the islands later part of next week. This will lead
to a decrease of the winds over the state. A mid-level ridge is
expected to rebuild north of the area as well at the same time,
resulting in a more stable airmass to return to the islands.
Forecast is trending toward a more typical trade wind weather for
the state later next week.


High pressure north of the state will keep a breezy to locally
windy trade wind flow in place through tonight, with showers
focused primarily over windward and mauka areas. Some temporary
CIG/VSBY restrictions will be possible over windward locales,
mainly through mid morning and again overnight tonight.
Otherwise, VFR conditions are expected to prevail.

AIRMET Sierra remains in effect for mountain obscuration across
windward sections of Kauai and the Big Island but will likely be
lifted early this afternoon.

AIRMET Tango remains in effect for moderate low level turbulence
downwind of the mountains of all islands. These conditions are
expected to remain in place through tonight.


A Small Craft Advisory (SCA) remains in effect through this
weekend for all Hawaiian waters due to strong and gusty trade
winds and elevated rough seas. The forecast models continue to
suggest the trade winds may ease slightly across some marine zones
early next week, and the SCA may be required mainly for the
typically windy waters adjacent to the islands of Maui County and
the Big Island Monday and Tuesday. Later next week, expect a
downward trend in trade wind speeds as high pressure to the north
of the state gradually weakens.

A small long-period east swell produced by former East Pacific
Hurricane Seymour arriving in the islands later today or tonight is
expected to continue through this weekend. In addition to this
swell, choppy surf will also increase due to the strong trades. As a
result, surf heights will likely approach the High Surf Advisory
threshold along most east facing shores of the island chain from
this weekend into Monday.

A series of small to moderate north and northwest swells are expected
from this weekend through early next week. Surf heights are
expected to remain below the High Surf Advisory criteria along
north and west facing shores of the islands. The latest guidance
from the Wave Watch III model shows a new long-period north-
northwest swell arriving early Wednesday. As a result, surf
heights may approach the High Surf Advisory criteria along some
north and west facing shores of the smaller Hawaiian Islands from
late Wednesday into Thursday.


Small Craft Advisory until 6 PM HST Sunday for all Hawaiian



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