Scientific Forecaster Discussion
fxhw60 phfo 300645
Area forecast discussion
National Weather Service Honolulu HI
845 PM HST Wed Mar 29 2017
light trade winds over the western end of the state will allow
for leeward afternoon sea breezes over Kauai and Oahu Thursday with
increasing afternoon clouds and brief showers. Moderate trade
winds will continue over the rest of the state with passing
windward showers. Trade winds will become breezy over the weekend
with increasing windward rainfall expected.
no changes in the forecast for this evening, with the current
forecast seeming to pan out well.
High pressure to the northeast is helping to maintain a trade wind
pattern over the eastern end of the island, with light east
southeast flow over the western end. A batch of moisture remains
upstream of The Big Island and is expected to increase shower
The lighter winds over the western end of the state will allow for
some afternoon sea breezes over leeward sections of the islands,
similar to what was seen today. High pressure is expected to build
north of the state Friday, which will help to strengthen the trade
winds, returning the state to a more typical trade wind weather
pattern. Trades are expected to increase this weekend to breezy to
windy levels, with showers mainly impacting windward and Mauka
Heading into the middle of next week, trade winds will weaken as
the high pressure weakens and a cold front passes by to the north
of the islands.
moderate trade winds will continue for the next few days. No
significant weather features are expected. Clouds and showers will
favor the windward and mountain areas. Localized MVFR ceilings/visible
can be expected for those areas, mainly overnight and early
morning. No airmets are expected at this time.
An upper level trough and jet is helping to produce light to
moderate turbulence between fl300/360 more than 250 nm northeast
of the state. The trough and jet are shifting to the east,
therefore no airmet Tango will be issued.
a large west-northwest swell (290-310 deg) associated with a
strong system far northwest of the state should reach the islands
Thursday night, peak Friday and Friday night, then slowly ease
over the weekend. Warning- and/or advisory-level surf for exposed
north- and west-facing beaches is expected during this time. All
of the models remain in close agreement for seas to ramp up
quickly Thursday night to Small Craft Advisory levels and peak in
the 10- to 14-ft range Friday, before slowly easing through the
weekend. If the swell comes in larger or later than predicted,
warning-level surf could continue into Saturday before dropping to
advisory levels Sunday.
Local winds and seas will likely remain below advisory levels
through Friday as the ridge of high pressure north of the state
slightly weakens in response to a cold front that is forecast to
approach the region later in the week. Advisory-level trade winds
will return across portions of the waters over the weekend as high
pressure builds north of the state behind this front.
Surf along east-facing shores will remain small and choppy due to
moderate to fresh onshore winds. Surf will begin to build over the
weekend as trade winds strengthen locally and upstream of the
islands, and may near or reach advisory levels along east-facing
shores by the end of the weekend and into early next week.
A slight increase in surf along south-facing shores is possible
Thursday through Saturday due to a long-period swell (190 deg)
from recent activity across the southern Pacific. In addition to
this south swell, wrap from the previously discussed large west-
northwest swell will add some to the mix by Friday at select spots
along exposed southern facing beaches.