Scientific Forecaster Discussion
fxhw60 phfo 190219
Area forecast discussion
National Weather Service Honolulu HI
419 PM HST Thu Jan 18 2018
a strong high north of the area will maintain windy conditions
over the islands tonight. Winds will gradually weaken starting
tomorrow as the high moves away to the northeast. A band of clouds
and showers along a stationary front that has been over Kauai
today will shift away to the north tonight. Clouds and showers
along a separate band will affect the windward side of The Big
Island and windward tonight. The two bands will merge tomorrow
and continue bringing clouds and showers to windward areas through
early next week.
a strong 1037 mb high about 1000 miles north of Oahu is forecast
to move east around 25 mph. The pressure gradient south of the
high is producing strong easterly trade winds over the islands.
Many stations on Maui County and The Big Island have been reporting
advisory level winds. Wind gusts at isolated locations in leeward
kohala on The Big Island have reached the High Wind Warning
threshold. Winds will remain strong today. Strong and low
temperature inversions will help force the winds to accelerate
around the island terrain. A High Wind Warning remains in effect
for kohala through early tomorrow morning with a Wind Advisory
for all other areas except the summits of The Big Island and Maui.
One or both products may need to be extended into tomorrow,
especially for portions of The Big Island and Maui.
Wind speeds will decrease on Friday and continue decreasing into
the weekend as the high shifts farther northeast. Winds near Kauai
and Oahu may shift out of the east southeast over the weekend as a
trough aloft and associated front approach from the northwest.
An east to west band of showery low clouds along a dissipating
stationary front has been focusing clouds and showers over Kauai.
A separate northeast to southeast band is bringing clouds and
showers to the windward side of The Big Island and Maui. Both
bands are expected to shift northwest tonight. Clouds and showers
over Kauai will likely decrease tonight as the band moves away,
while the second band will continue to focus clouds and showers
over the windward side of Big Island and Maui overnight. The
bands are expected to merge tomorrow. Remnants of the bands will
bring showers to windward areas through early next week.
strong trade winds are producing moderate to severe turbulence
near and downwind of the terrain. Airmet Tango continues. This
airmet also includes strong surface winds across all islands.
VFR conditions will prevail, however passing clouds and showers
will bring periods of MVFR conditions over mainly east sections.
Extensive mountain obscuration is not anticipated, but
observations will be monitored for its possible issuance.
a Gale Warning remains in effect through tomorrow morning, while
a Small Craft Advisory (sca) remains in effect for the rest of the
areas due to a combination of winds and seas. Strong to gale-
force winds are forecast to hold through tonight, then gradually
trend down Friday through the weekend as a strong high to the
north shifts east. We expect to be able to drop the Small Craft Advisory for some
areas beginning tomorrow.
A high surf advisory (hsa) remains in effect for east facing
shores through tomorrow night, but may need to be extended. Surf
will likely hold around the 8 foot advisory level along east
facing shores through the weekend due to a large area of fresh to
strong trades well east of the state, despite the winds trending
Surf along north and west facing shores continues to drop and is
expected to remain below advisory levels through the weekend. A
small northwest swell is expected Sunday, that will be reinforced
with a moderate northwest swell by Monday. Surf from the new swell
could reach reach advisory levels. This reinforcement will peak
by late Monday, then gradually lower through midweek.
High Wind Warning until 600 am Friday for kohala.
Wind Advisory until 600 am Friday for all areas except kohala and
the summits of Mauna Kea, Mauna Loa and Haleakala.
High surf advisory until 600 am Friday for east facing shores of
Kauai, Oahu, Molokai, Maui and The Big Island of Hawaii.
Gale Warning until 600 am Friday for the pailolo and alenuihaha
channels, Maalaea Bay and waters south of The Big Island.
Small Craft Advisory until 600 am Friday for Kauai leeward
waters, Oahu leeward waters and Maui County leeward waters.
Small Craft Advisory until 600 PM Friday for all other Hawaiian