Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Honolulu HI
400 am HST Thursday Dec 12 2013
trade winds will gradually diminish the next couple of days and
turn southeasterly by the weekend as an advancing front stalls
briefly west of the state. Light windward showers will continue into
the weekend with some afternoon cloud buildups over interior areas
of the islands. The front may resume its course to the islands
Sunday into early next week...bringing wetter weather and a slight
chance of thunderstorms to the state.
an area of low clouds have reached the islands earlier this
morning...providing some showers to mainly windward areas. The
surface high pressure that has been providing trade winds to the
state is moving steadily east early this morning...as a cold front
from the northwest pushes closer to the state. This will lead
to a decrease in trade winds for the next couple of days over the
islands. Early morning Lihue and Hilo soundings both revealed a
typical trade wind weather profile...with low level moisture
extending to about 6k feet. Air mass is dry and marginally stable.
Therefore precipitation from the passing clouds will be limited.
Trade wind weather will continue today...with passing clouds and
showers affecting mainly windward areas.
Latest forecast model solutions still indicate this approaching
front will stall west of Kauai in the coming days. Therefore
southeasterly winds ahead of this system will slowly spread over the
Western Islands by the weekend...while more typical trade winds will
prevail over Maui County and The Big Island. The Western Islands
may see a hybrid convective and trade wind weather regime...with
land and sea breezes becoming more prominent by the weekend. Clouds
and possible showers will develop over the interior sections of the
islands under day time heating...while night time cooling will
result in partial clearing of skies over those islands. Low clouds
carried by the winds may still affect the windward areas at times.
Maui County as well The Big Island should see more typical trade
wind weather...with passing low clouds and showers affecting mainly
windward and mountain areas. Volcanic haze from The Big Island may
reach the Western Islands at times under the increasing
southeasterly wind flow.
The stalled front is still expected to resume its advance towards
to the islands by the later part of the weekend into early next week
as another system from further northwest pushes east. The chance of
rain will increase over Kauai Saturday night as the front edges
closer to the island...then spread over Oahu and Maui County by
Sunday into early next week as the front moves east. The atmosphere
will also become more unstable over the islands as cold air aloft
associated with the front reaches the state...bringing a slight
chance of thunderstorms Sunday through early next week...with
possible heavier rainfall.
The global model solutions diverge somewhat in the extended period
over the islands...though both models have another frontal system
approaching the state from the northwest. GFS has a surface trough
developing east of the islands...resulting in northeast trade winds
over the state while the European model just indicate an area of
moisture persist east of the state...with southeasterly winds over
the islands ahead of the frontal system. Have sided with GFS at time
though this forecast certainly is subjected to change with future
VFR conditions will prevail throughout the islands today...though
brief MVFR conditions are possible due to the passing
showers...mainly over windward areas.
the Small Craft Advisory has been cancelled with the weakening winds.
A large northwest swell will build rapidly Friday afternoon...bringing
possible advisory level surf for north and west facing shores Friday
afternoon through Saturday. This swell may be large enough to bring
small craft seas conditions to the exposed coastal waters for the