High Surf Advisory 36, NWS Honolulu, HI

Area Forecast Discussion
National Weather Service Honolulu HI
937 AM HST SAT JUL 2 2016

.SYNOPSIS...
Strong and gusty winds will continue through today, then decrease
slightly through the rest of the holiday weekend. Airmass moisture
will gradually increase as well, allowing a trade wind pattern of
showers, favoring windward and mauka areas, to form over the next
few days.

&&

.DISCUSSION...
A 1033 MB high near 37N152W, far north of the main Hawaiian
Islands, is driving strong and gusty trade winds across the aloha
state this morning. High clouds along the eastern flank of an
upper low far west of the islands are moving northeastward across
local waters, while patchy broken low clouds riding the trades
continue to affect windward shores and slopes of the islands.
Radar shows very little shower activity, which isn't surprising
given our rather stable airmass and a strong inversion between 5000
and 6000 feet. Overnight soundings show boundary layer winds in
the 25 to 35 knot range. We expect these strong winds will mix
down toward the ground as daytime heating increases, causing
speeds to pick up once again today. Therefore, a wind advisory
remains in effect for all islands through this afternoon, while
gale warnings and small craft advisories are in effect for local
waters.

Models continue to show that the strongest winds are occurring
just off the surface now and will continue into this morning
before slowly diminishing after this afternoon. Rather dry
conditions will persist today. A few showers may affect the
windward Big Island and windward East Maui, but little to no rain
is expected elsewhere. Trade winds will ease somewhat tonight and
Sunday, and shower activity is expected to return to more normal
levels as the inversion rises and increased low-level moisture
moves into the state from the east. Expect passing but more
frequent showers over windward areas, with the breezy trade winds
carrying some showers over leeward portions of the smaller islands
at times.

A wetter trade wind pattern appears to be in store from Sunday
night through at least Tuesday, as areas of increased low-level
moisture move through the state. Showers will continue to favor
windward and mauka areas, but some will be carried leeward in the
trade wind flow. Somewhat drier and less breezy trade wind
conditions may develop around midweek and continue through the
later part of the week.

&&

.AVIATION...
Strong, gusty trade winds and stable atmospheric conditions will
persist, supporting the continuation of AIRMET Tango for moderate
to isolated severe low level turbulence over and immediately S
through W of terrain on all islands. Sustained surface wind speeds
of 30 knots is also included in AIRMET Tango.

VFR conditions will prevail, with the stable trade wind flow
providing shallow low clouds that may occasionally become
widespread enough along windward slopes and coasts to lead to
isolated MVFR ceilings.

&&

.MARINE...
ASCAT and ground observations support keeping the current
Small Craft Advisory and Gale Warning in place through the day
today. Although the winds will begin to ease Sunday through the
upcoming week, the Small Craft Advisory will likely be extended in
later forecast packages, mostly for the windier marine areas from
the Pailolo Channel to the waters south of the Big Island.

Advisory-level surf will remain possible along east facing
beaches due to the strong trade winds, beginning as early as
tonight. Elsewhere, no significant surf is anticipated through the
weekend. Looking ahead through the upcoming week, the latest hi-
res wave model guidance has begun to reflect a small to moderate
south swell by the end of next week in response to the recent gale
located east of New Zealand. Although later observations at the
buoys farther south across the Pacific will need to be monitored
over the coming days, this southerly source will likely support
near advisory-level surf along the south facing shores by next
Friday. Please refer to the recently issued Collaborative
Nearshore Swell and Wind Forecast (SRDHFO) for more details.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 PM HST this evening for all Hawaii islands.

Gale Warning until 6 PM HST this evening for Pailolo Channel-
Alenuihaha Channel-Big Island Leeward Waters-Big Island
Southeast Waters.

Small Craft Advisory until 6 PM HST this evening for Kauai
Windward Waters-Maui County Leeward Waters-Big Island Windward
Waters.

Small Craft Advisory until 6 PM HST Sunday for Kauai Northwest
Waters-Kauai Leeward Waters-Kauai Channel-Oahu Windward Waters-
Oahu Leeward Waters-Kaiwi Channel-Maui County Windward Waters-
Maalaea Bay.

&&

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