High Surf in Hawaii, January 7 to 11, 2017

Area Forecast Discussion
National Weather Service Honolulu HI
956 AM HST Sat Jan 7 2017

.SYNOPSIS...
Cool northeast winds will prevail today, and nighttime
temperatures will continue on the cool side. Trade winds on
Sunday will give way to lighter winds next week, with sea breezes
prevailing in the afternoons. Mostly dry and warmer conditions are
expected for next week, but volcanic haze from the Big Island may
spread over the smaller islands by midweek.

&&

.DISCUSSION...
Clouds and light showers are affecting the northern slopes of the
state this morning, while the rest of the area is under clear
skies with cool dry winds blowing from the northeast. Dew points
across the state remain in the mid 50's, providing chilly
overnight low temperatures and dry, warm daytime conditions.
Any showers will be limited and most will remain over the windward
slopes.

The current NE flow over the islands will continue into tonight before
shifting to the east Sunday as a front pushes into the Central
Pacific from the west. The front will force a surface ridge over
Kauai Monday with winds diminishing to light and variable over the
smaller islands, while modest trade winds remain over the Big
Island. The front will approach Kauai Monday and Monday night but
is not expected to reach the Garden Isle as it stalls about 200
miles to the north. The ridge will remain near Kauai through
Tuesday and variable winds will continue for the smaller islands
with daytime sea breezes and nighttime land breezes.

A second front moving toward the islands Wednesday will push the
ridge farther south and allow for increasing southerly winds over
Kauai and Oahu. The south component of the winds will allow
volcanic haze from the Big Island, or vog, to move up over the
smaller islands and into windward sections of the Big Island. The
change in the low-level flow will result in increasing dew point
temperatures, and with values expected to climb into the mid 60s,
it will feel less chilly by early next week.

A wind advisory remains over the Big Island summits as a closed
low far northeast of the area has accelerated winds above 10
thousand foot elevation. The Advisory remains through today, but
winds are expected to diminish late this afternoon as the low
moves farther away from the Big Island.

&&

.AVIATION...
High pressure building in from the northwest will keep the
airmass over the state mostly dry and stable. Multiple bands of
cumulus moving in from the north will bring ISOL MVFR to the
windward slopes today and this evening. Otherwise VFR conditions
expected to prevail all areas.

AIRMET TANGO is in effect for MOD CAT aloft between FL310 and
FL380. Conditions should improve later today but are expected to
redevelop overnight.

&&

.MARINE...
Winds over the coastal waters will remain below Small Craft Advisory
criteria through the weekend and on into the middle of next week.
Winds will blow from the north and northeast today before swinging
around to the east on Sunday. As a ridge of high pressure moves
over the area early next week, winds will become rather light
favoring a general southeasterly direction. However with the winds
being so light, local land and sea breezes will prevail in many
locations. Seas will also remain below advisory levels with
significant wave heights generally running in the 5 to 8 foot
range over the most exposed waters. A new northwest swell arriving
on Wednesday may cause seas to reach advisory levels over exposed
waters.

The current north northeast swell will linger through the weekend
then lower into early next week. Another north northeast swell
will gradually fill in Monday night and Tuesday, then linger
through the middle of next week. The current High Surf Advisory
posted for east facing shores may be lowered later today or
tonight. The new swell arriving early next week could boost surf
heights once again to near advisory levels along east facing
shores.

A small short period northwest swell will fill in Monday night
and Tuesday. A larger northwest swell is expected to arrive on
Wednesday, peak Wednesday night and early Thursday, then lower
gradually on into Friday. Surf heights are expected to reach
advisory levels during the peak of the swell. A small south swell
is also on tap during the Monday through Wednesday time period.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 6 PM HST this evening for Kauai
Windward-Oahu Koolau-Olomana-Molokai Windward-Maui Windward West-
Windward Haleakala-Big Island North and East.

Wind Advisory until 6 PM HST this evening for Big Island Summits.

&&

Morrison...Discussion
Burke...Marine
Bedal...Aviation