Strong Wind in Hawaii, January 7, 2020

Area Forecast Discussion...CORRECTED
National Weather Service Honolulu HI
342 AM HST Tue Jan 7 2020

.SYNOPSIS...
Strong and gusty trade winds will continue through the week.
Showers will focus over windward areas with some reaching leeward
locations of the smaller islands. Wetter weather is likely during
the second half of the week as a low aloft moves near the
islands.

&&

.DISCUSSION...
A strong high pressure remains parked far northeast of the state
with a current pressure near 1035 mb. The high will continue to
bring strong trade winds through the week as it moves to a
position north of the state and strengthens to near 1040 mb. A
High Wind Warning is in effect for the Kohala Districts of the Big
Island and a Wind Advisory is in effect for parts of lower
elevations of Maui county and the Big Island of Hawaii through
Wednesday evening. There is also an Wind Advisory in effect for
the summits of Mauna Loa and Mauna Kea. Strong winds will continue
through the week and these advisory/warning products will be
updated as necessary.

Scattered showers can be found racing westward across the
windward waters and windward island locations. Cloud tops are
higher than our normal 8-10 thousand feet with current tops
reaching 15 to 20 thousand feet with isolated pockets reaching 25
thousand feet. An upper level low centered east of the state is
providing the instability for the higher tops. The overnight Hilo
sounding measured a 500mb temperature of -11.5 Celsius which
indicates slight to moderate instability. Global models show some
colder 500 mb temps farther east of the state in the vicinity of
the upper low. The low is forecast to meander east of the area
through Wednesday before moving westward toward the state. The
current forecast brings in the effects of the upper low to the
eastern half of the state Wednesday night, and the rest of the
state Thursday and Thursday night. Increasing shower coverage and
intensity is expected with the possibility of isolated
thunderstorms accompanying the heaviest showers.

&&

.AVIATION...
A strong high pressure system north to northeast of the Hawaiian
Islands will produce breezy to windy trade winds through the
week. Winds this strong will produce low level moderate turbulence
along and south through west of mountain ranges on all islands.

An upper level low lingering just east of the island chain will
continue to produce bands of showers spreading westward in the
trade wind flow mainly during the overnight and early morning
hours. Periods of mountain obscurations are possible for north
though east sections of each island. Upper level winds around this
low are strong enough for moderate turbulence aloft between
FL250-350 across all islands.

AIRMET Sierra remains in effect for tempo mountain obscurations
along north through east facing sections Kauai, Oahu, Molokai,
Maui and the Big Island. This AIRMET will decrease in coverage
after 18Z this morning.

AIRMET Tango remains in effect for tempo moderate turbulence
below 090 over and south through west of mountains. Another AIRMET
Tango remains in effect for moderate upper level turbulence due
to strong winds aloft. These turbulence AIRMETs will likely
continue through at least the next 24 hours. AIRMET Tango for
strong surface winds greater than 30 KTS also remains in effect.

&&

.MARINE...
Strong high pressure will prevail to the NE of the islands for the
foreseeable future, producing strong to near gale force winds
near and upstream of the islands. Where winds are most accelerated
by island terrain, they are reaching gale force over some marine
zones. See the Marine Weather Message (MWWHFO) for details on the
ongoing Gale Warning and Small Craft Advisory.

A High Surf Advisory is in effect for E facing shores of most
islands, and the rough and choppy high surf will persist into the
weekend. Short-period seas are forecast to build through the week
(to near 15 feet or more) in response to the persistent upstream
fetch of trade winds, and surf along E facing shores could
approach warning levels as early as tomorrow, but more likely
Thursday into Friday. See the Coastal Hazard Message (CFWHFO) and
the Oahu Surf Discussion (SRDHFO) for additional information. The
combination of high surf, strong onshore winds and elevated ocean
water levels will result in beach erosion and wave runup along E
facing shores later in the week, when full moon high tides
coincide with the elevated surf.

Little in the way of significant swell is otherwise expected,
with only a small northwest swell anticipated through Wednesday. A
moderate long-period northwest swell arriving Friday could
produce surf close to advisory levels into Saturday. A smaller
northwest swell may arrive Sunday into Monday.

&&

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

Wind Advisory until 6 PM HST Wednesday for Lanai-Kahoolawe-Maui
Central Valley-South Big Island-Big Island Interior-Big Island
Summits.

High Wind Warning until 6 PM HST Wednesday for Big Island North
and East-Kohala.

Gale Warning until 6 PM HST Wednesday for Maalaea Bay-Pailolo
Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island
Southeast Waters.

Small Craft Advisory until 6 PM HST Friday for Kauai Northwest
Waters-Kauai Windward Waters-Kauai Leeward Waters-Kauai Channel-
Oahu Windward Waters-Oahu Leeward Waters-Kaiwi Channel-Maui
County Windward Waters-Maui County Leeward Waters-Big Island
Windward Waters.

&&

DISCUSSION...Morrison
AVIATION...Bohlin
MARINE...Birchard