Marine Weather and Tides
10/6/2018 Colors of tide XTide graphs changed to emphasize that they were upgraded. See next note. Comments welcome.
10/4/2018 I have fixed XTide and updated the harmonic files. There were some name changes so you might have to click EDIT to find the new station name.
|Sunrise 7:00AM||Sunset 6:32PM||Sunday February 17, 2019 3:39 PM HST (01:39 UTC)||Moonrise 4:19PM||Moonset 5:04AM||Illumination 98%|
7 Day Forecast for Marine Location Near Kekaha, HIHourly EDIT Help
Area Discussion for -  (on/off)  Help NOTE: mouseover dotted underlined text for definition
|Fxhw60 phfo 171956|
area forecast discussion
national weather service honolulu hi
956 am hst Sun feb 17 2019
Breezy northerly winds and showery conditions will continue across
the western end of the state into tonight as low pressure lingers
to the north. Drier conditions along with a transition to light
and variable winds are anticipated for the eastern end of the
island chain through early Monday. A return to wet and unsettled
conditions is expected late Monday into Wednesday for mainly the
big island and maui county, where a plume of deep tropical
moisture is forecast to setup. Improving conditions will be
possible during the second half of the week.
A locally breezy and wet northerly flow remains in place over the
western half of the state, while drier conditions and light and
variable winds are setting up for the eastern end of the state. A
surface low centered roughly 250 miles north of the big island is
responsible for the contrasting weather regimes, and a persistent
broad upper level trough parked across the region is maintaining
A moist northerly flow with precipitable water (pw) values around
1.25 inches is streaming over kauai, oahu, and molokai, where
light to moderate showers have deposited generally less than an
inch of rainfall along windward and north facing slopes in the
past 12 hours. That said, a few interior kauai gages have picked
up in excess of 2 inches during this time, and since this shower
activity will persist today and a few briefly heavy showers are
possible, we will have to keep an eye on the kauai rivers, which
have low odds of having significant rises today. No flood concerns
are present on oahu and molokai, where a few showers will spill
over to leeward areas through the day.
A slightly unstable light and variable wind regime is in place on
the big island and will push over to maui later today. The big
island is starting out mostly clear, while the fading northerly
flow on maui is sending some showers to north facing terrain. Pw
is down around and inch, but afternoon sea breezes will produce
interior clouds and spotty showers, mainly over the terrain.
Tonight and early Monday will serve as a transition period,
marking the end of the recent, extended spell of breezy and cool
conditions. The surface low will move westward and pass a couple
hundred miles north of kauai on Monday. This will slacken the
local pressure gradient and cause winds to go light and variable
state-wide on Monday. The persistent upper level trough that has
dominated our weather for more than a week will begin to
strengthen once again. This will lead to increased instability,
especially near the core of the reinvigorated mid to upper level
low setting up just west of kauai. As a result, a few heavy
showers, and possibly a thunderstorm, may develop over the
interior of kauai and oahu in the afternoon. Otherwise, mostly
clear morning conditions will give way to sea breezes with
afternoon clouds and spotty showers.
Wet and unstable conditions will develop over the eastern half of
the state Monday night and persist through at least Tuesday. The
weather feature of concern is a deep plume of tropical moisture
currently sitting 400 to 700 miles east of the big island. As the
surface low to our north drifts westward, this broad zone of
convergent southerly flow with pw values around 2 inches will
spread over the big island and maui. The upper level trough
centered just west of the islands will sharpen, setting up a
region of divergence over the plume of deep moisture. Chances for
heavy, flooding rainfall and thunderstorms look very high for the
big island and maui at this time, while islands to the west of the
plume remain under an unstable land and sea breeze regime. Strong
winds and winter weather are expected over the high summits of
the big island, though snow levels will be much higher (11,000 to
12,000 ft) which will likely eliminate any chance of winter for
the haleakala summit on maui.
Although this plume of moisture may linger over the far eastern end|
of the state into the latter half of the week, conditions should
begin to gradually improve. Guidance suggests the upper and surface
low to the west ejecting northward with a weak surface ridge
nosing in to the north of islands. Pws will likely hover around an
inch to 1.4 inches near the big island. Winds could transition
back out of the north to northeast Thursday through Friday in the
light to moderate range.
A complex low pressure system with a primary center about 230 nm
north of the big island will continue to spread clouds and showers
across the smaller islands. A trough of low pressure extends
southward from the low across eastern maui and is forecast to move
slowly westward over the next 24 hours. Light surface winds out
of the south winds lie to the east of the trough, and locally
strong northwest winds lie to the west of the trough.
Clouds and showers will favor north through northwest facing
slopes and coasts today then north through northeast facing slopes
and coasts tonight. Radar indicates MAX tops up to 15 kft over
kauai and oahu indicating the potential for brief locally heavy
downpours in these areas. Airmet sierra is expected to remain
necessary over kauai through at least early evening. Drier
conditions are expected over and around the big island where most
shower activity is expected to remain off the coast.
The radar derived low level winds from the south kauai radar
indicate north winds at summit level up to 30kt. Airmet tango
likely to remain necessary through early evening.
A surface low about 230 nm N of big island is forecast to track
west through Monday. A trough extends southwest of the low to the
alenuihaha channel. There will be fresh to strong north winds west
of the trough and light to moderate variable winds east of the
trough. As the trough shifts west over the next few days, fresh
to strong southeast winds will spread over the eastern offshore
waters, but are not expected to reach the hawaiian coastal waters.
Local nearshore buoys exposed to the northeast swell continue to
show significant wave heights between 10 and 14 feet with a period
of about 12 seconds. Surf from this swell is expected to remain
at high surf advisory (hsa) levels along north facing shores
through today and at high surf warning (hsw) levels along east
facing shores (where the threshold is lower). Surf along east
facing shores is expected to hold through tonight and begin
dropping off on Monday, so the hsa and hsw may need to be
extended through tonight. A new west-northwest swell should peak
today and gradually subside through the middle of the week.
A small craft advisory (sca) is in effect through late tonight
for most hawaiian waters, mainly for the large seas associated
with the northeast swell, however winds will remain above sca
levels today in waters around kauai county. With the new west-
northwest swell building today, expect seas to remain above the
10 ft SCA threshold in many locations at least through tonight.
Seas should begin to subside on Monday, but may remain above the
10 foot criteria through Monday night for select coastal waters.
Hfo watches warnings advisories
High surf advisory until 6 pm hst this evening for north facing
shores of the big island, maui, molokai, oahu, kauai, and niihau.
High surf warning until 6 pm hst this evening for east facing
shores of the big island, maui, molokai, oahu, kauai, and niihau.
Small craft advisory until 6 am hst Monday for kauai northwest
waters-kauai windward waters-kauai leeward waters-kauai channel-
oahu windward waters-oahu leeward waters-kaiwi channel-maui
county windward waters-pailolo channel-alenuihaha channel-big
island windward waters-big island southeast waters.
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