Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Honolulu HI
359 PM HST Wednesday Nov 25 2015
a surface trough with a northeast to southwest axis across Maui will
slowly move westward across the central and Western
Islands...keeping unsettled weather for these areas through Friday
night. Drier and more stable air will build in over the weekend
and and into next week...reducing the overall shower activity and
confining it to primarily windward and Mauka locales.
a weak surface trough is located across Maui this afternoon...and
slowly moving to the west. Fresh north northeast trade winds will
continue through the next few days driven by high pressure north
of the state...particularly across the western end of the state
through Friday. Radar imagery shows widespread showers
concentrated over Molokai...and across windward Oahu and Maui to a
lesser extent. These showers are occasionally reaching leeward
sides of the islands...but quickly passing through as the breezy
trade winds carry them.
For tonight through Friday night...expect the clouds and showers
to continue over the central part of the state...then slowly
migrating towards the Western Islands as the trough slides
westward. Conditions will become drier over Maui and The Big
Island over the next 24 hours. Showers will focus primarily
across windward and Mauka areas...but the breezy trades will allow
some showers to make it into leeward areas as well.
The breezy trades will likely continue through the weekend...but
showers are expected to decrease on Saturday. A ridge building aloft
along with a decrease in low level moisture...will lead to a
decrease in shower activity across the island chain. As a
result...expect more typical weather...with more diffuse clouds
and showers focused primarily over windward and Mauka areas...and
generally dry and sunny weather in leeward locales.
The trade winds are expected to weaken somewhat during the first
half of next week as a cold front approaches from the north.
enhanced moisture along a nearly stationary dissipating trough will
keep wet conditions...with MVFR to isolate IFR conditions...over most
of Maui County through the night. Airmet Sierra for mountain obscure
remains posted for Molokai Lanai and Maui. High pressure to the northwest
will continue to shift east and moderate to strong trade winds can be
expected throughout the state. Airmet Tango for low level turb S
through west of the mountains is posted for all islands.
The elevated trade winds will aide in pushing enhanced moisture
towards the windward areas of the other islands...especially Oahu
tonight. Airmet Sierra will be expanded as needed. Remaining leeward
areas should carry predominately VFR conditions.
high pressure building north of the state will drive locally
strong northeast trade winds across the marine area through the
day...with winds or seas reaching Small Craft Advisory /sca/
levels in most marine zones. As a result...Small Craft Advisory is in effect for
most of the marine zones through Thursday night...see advisory
list below for affected areas. The Small Craft Advisory may need to be extended
for some areas into the weekend...due to a continuation of the
breezy trade winds and incoming northwest swells.
A small northwest swell will persist through Friday. A large
northwest swell is expected to arrive Friday night...peak late
Saturday and Saturday night...then slowly subside early next week.
Surf heights will exceed advisory levels and may reach low end
warning levels during the peak of this swell episode.
There will be a series of small south swells throughout the forecast
period. Elsewhere...strengthening trade winds will cause an
increase in short period choppy surf along east facing shores
at least through the weekend.
Small Craft Advisory until 6 am 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-Maalaea Bay-Pailolo Channel-Alenuihaha
Channel-Big Island leeward waters-Big Island southeast waters.
Small Craft Advisory until 6 am HST Thursday for Maui County