Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Honolulu HI
400 am HST Friday Dec 13 2013
a front approaching the state from the northwest will keep winds
light enough over the islands allowing land and sea breezes to
develop through the weekend. Afternoon clouds and possible showers
will develop over the interior areas of the islands while the
southeast flow may bring some clouds and showers to the windward
areas at times. Wetter weather will affect the state Sunday and
Monday as the front reaches the islands.
low clouds did clear Oahu and Molokai early this evening under the
land breezes while east to southeast winds continue to bring low
clouds and showers to windward Maui and Big Island. There are also
high clouds streaming across the state as well this morning and
these high clouds may keep the skies a little more cloudy today.
Synoptic wind flow over the islands is mainly southeasterly as
indicated by early morning soundings...though wind profiles from the
Kauai and Molokai radar suggest there are some easterly winds at the
lowest level. Still expect mainly southeast winds to prevail across
the state today...due to the present of a stalled front northwest of
the islands. Winds will remain light over the Western Islands as
much of the southeast winds are blocked by the eastern islands. With
the light winds...sea breezes will develop during the day while sea
breezes will form during the night. Clouds will develop over the
interior sections of the islands under daytime heating...and may
bring some showers as well...while night time cooling will bring
subsidence over the islands resulting in partial clearing of the
skies. Low clouds embedded in the synoptic southeast wind flow may
reach the islands as well...affecting mainly the windward areas and
bringing some showers. Early morning soundings from Lihue and Hilo
have moistened up a bit...though there is still a good inversion at
the Lihue sounding at around 5k feet. At least the air mass in the
island vicinity has become moist enough to support wetting rain.
Temperatures across the islands may feel warmer during the day due
to a lack of wind. Volcanic haze from The Big Island may spread over
the Western Islands late in the weekend under the southeasterly flow.
The front will remain stall through early Saturday...therefore the
current weather pattern will persist over the islands through much
of Saturday. This front will resume its movement later Saturday into
Sunday as another cold front descending down from the North Pacific
will displace it eastward towards the state. The chance of rain will
increase over Kauai late Saturday into Sunday while Oahu and Maui
County will see increasing chances of rainfall by Sunday as the
front advances along. The atmosphere will also begin to destabilize
as cold air aloft associated with the system passes across the
island chain...bringing a slight chance of thunderstorms as well as
the potential of locally heavy rain to the smaller islands mainly
Sunday. This front is expected to weaken and dissipate by
Monday...allowing trade winds to return to the state by Tuesday.
Lingering moisture from the dissipated front may continue to affect
the islands...mainly over the windward areas.
Model solutions once again differ somewhat over the islands in the
extended forecast period...as the European model indicate a surface
trough may pass over the islands during the later part of next week
while GFS pretty much kept trade winds across the state. Have opted
to blend the model solutions for the extended forecast
periods...which still show mainly trade winds as well as trade wind
weather over the state.
mainly VFR conditions will prevail across the state...though low
clouds carried by the east to east-southeast low level flow may bring isolate MVFR
ceilings over east facing terrain today. No airmet is expected.
a large northwest swell will build rapidly later today...bringing advisory
level surf for north and west facing shores late this morning
through Saturday night. This swell may be large enough to bring
small craft seas conditions to the exposed coastal waters at the
high surf advisory from 10 am HST this morning to 6 am HST Sunday
for Niihau-Kauai windward-Kauai leeward.
High surf advisory from 4 PM HST this afternoon to 6 am HST Sunday
for Waianae coast-Oahu North Shore-Oahu koolau-Molokai-Maui windward
west-Maui Central Valley-windward Haleakala.
Small Craft Advisory from 4 PM HST this afternoon to noon HST
Saturday for Kauai northwest waters-Kauai windward waters-Kauai
leeward waters-Oahu windward waters-Kaiwi Channel-Maui County
windward waters-Big Island windward waters.