surf zone forecast
National Weather Service Honolulu HI
300 PM HST sun Mar 21 2010
hiz005>011-220500-
Oahu-
300 PM HST sun Mar 21 2010
...High surf advisory for south facing shores...
Surf along south facing shores will be 8 to 10 feet...lowering to 6
to 8 feet Monday.
Surf along north facing shores will be 4 to 6 feet...lowering to 2
to 4 feet Monday.
Surf along west facing shores will be 5 to 10 feet...lowering to 4
to 7 feet Monday.
Surf along east facing shores will be 3 to 5 feet through Monday.
Outlook through Saturday Mar 27:
the current south swell will gradually diminish Monday and Tuesday.
A new northwest swell arriving Tuesday is expected to boost surf
heights well above the advisory thresholds along north and west
facing shores late Tuesday and Wednesday.
Surf heights are forecast heights of the face or front of waves. The
surf forecast is based on the significant wave height...the average
height of the one third largest waves...in the zone of maximum
refraction. Some waves may be more than twice as high as the
significant wave height. Expect to encounter rip currents in or near
any surf zone.
&&
Collaborative nearshore swell and wind forecast for Oahu
NWS/ncddc Honolulu HI
300 PM HST Fri Mar 19 2010
This collaborative forecast will be updated Monday through Friday at
300 PM when pat Caldwell is available. When pat Caldwell is not
available...the latest collaborative forecast will remain posted for
4 days.
Forecast swl dmnt dmnt h h hgt wind wind spd
date hgt dir pd 1/3 1/10 tend prob spd dir tend
1 PM 5 NW 15 8 10 down 17-21 NE same
03/19 10 NNW 13 18 22 same
8 NE 8 4 6 same
2 SSE 13 2 4 down
1 SSW 25 2 4 up
Sat 7 NNW 12 10 14 down Med 17-21 ENE same
03/20 8 NE 8 4 6 same Med
4 SSW 20 8 10 up Med
Sun 4 NW 15 6 8 up low 11-16 E down
03/21 6 ENE 7 2 4 down low
4 SSW 17 6 10 same low
Mon 3 NW 13 4 6 down low 7-10 ENE same
03/22 4 S 14 6 8 down Med
Tue 10 NNW 16 20 26 up low 11-16 NNE up
03/23 5 NNE 7 2 4 up low
3 S 13 4 6 down low
Wed 9 NNW 14 16 22 down low 11-16 NE same
03/24 5 NE 7 2 4 same low
2 S 13 2 4 down low
Legend:
swl hgt open ocean swell height measured from trough to crest
in feet located 20 nautical miles offshore
dmnt dir dominant direction typically +/-10 degrees in 16 Compass
points
dmnt pd dominant period in seconds
h1/3 significant wave height in the surf zone
h1/10 average height of the highest one-tenth waves in the surf
zone
hgt tend height tendency of swell (valid values: up/down/same)
prob probability of occurrence (valid values: high/Med/low)
wind spd open water wind speed measured in knots located
20 nautical miles offshore
wind dir wind direction in 16 Compass points
spd tend wind speed tendency (valid values: up/down/same)
Surf heights will vary between different beaches and at the same
beach at different break areas.
Discussion:
summary...
Spring to arrive with waves from both hemispheres.
Detailed...
mid Friday on northern shores has high surf from a mix of sources.
Longer period energy from 315-330 degrees is arriving from a source
near the Kuril Islands earlier in the week. Shorter period swell is
arriving from a nearby source out of 330-360 degrees. Buoy 51101 and
wave model output both suggest the peak of the coinciding episodes
should be near noon Friday. The latter source should drop off
quickly due to proximity. Surf should fall to moderate to marginally
high levels by dawn...and down to the moderate category by noon.
Surf should fall to small levels on Sunday.
A short-lived...storm-force system in the far NW Pacific east of
Kamchatka on Wednesday into Thursday aimed swell north of Hawaii.
Angular spreading should bring in a small episode locally...building
Sunday from 320-330 degrees and dropping on Monday.
Models show a low pressure deepening rapidly on Saturday as the
system occludes near 45n in the longitudes between Hawaii and the
dateline. Severe gale to storm force winds are expected starting
Saturday in the 325-345 degree band. Models show the center jogging
to the se on Sunday...that would give a captured fetch with the head
of gales reaching about 900 nm away late Sunday. The system is
expected to weaken and drift east on Monday.
High to extra-large breakers are expected to build in the wee hours
on Tuesday from 325-350 degrees...peaking late Tuesday...and slowly
dropping on Wednesday from 335-360 degrees.
Mid Friday on Eastern Shores has small to moderate windswell
breakers from 30-50 degrees and higher sets for more northerly
exposures from the nearby source described above. The windswell
should stay about the same into early Sunday then fall into Monday
as the trades veer more to east and slowly decrease in speed.
Another round of breezes behind a weak front are expected on
Tuesday...starting from 010-030 degrees and slowly veering to 30-50
degrees on Wednesday. Small windswell is expected.
Mid Friday on Southern Shores has small..long-period breakers from a
dropping episode out of 160-170 degrees and a slowly rising episode
from 190-200 degrees. The latter is expected to continue to build on
Saturday.
A complex area of low pressures to the immediate S to se of New
Zealand a week ago Thursday into Sunday set up a long fetch of
severe gale to storm-force winds over the 185-200 degree band. Wave
models were validated well by the Jason satellite showing a wide
area of seas over 35 feet to the se of New Zealand. The primary
center of low pressure tracked toward the NE last Friday into
Saturday...allowing a captured fetch...with the head of gales
reaching within 4000 nm by late Saturday. The system slowly tracked
east into Tuesday as it weakened.
Wave models are showing above average...long-period swell building
Friday night into Saturday for Hawaii...leading to high surf from
185-200 degrees. Since forerunners are already sensed at the kilo
nalu sensor...confidence is lifted for the arrival of high surf. The
episode should be long-lived...with a slow downward trend Sunday
night...dropping below high levels mid Monday...and continuing a
decline to small to moderate levels by late Tuesday. The latter days
should be from 175-200 degrees.
Into the long range...tropical cyclone Tomas tracked se to the NE of
New Zealand on Wednesday...though the quadrant aimed at Hawaii had a
short fetch. This may be enough to keep small breakers next
Thursday. Another extratropical cyclone tracked to the se of New
Zealand
on Thursday into Friday...and could give a moderate episode from
180-200 degrees starting March 26.
In the northern hemisphere...a low pressure system with gales is
expected to cross the dateline Wednesday...and pass north of Hawaii
on Thursday with storm-force winds...bringing in potentially a
marginally high surf episode by late on March 27 from the NNW to N.
Moderate to fresh trades are expected that weekend.
Long range forecasts are subject to high uncertainty.
This collaborative forecast will resume on Monday...March 22.
This forecast was produced through the collaborative efforts of
NWS and ncddc. Please send suggestions to W-hfo.Webmaster@noaa.Gov
or call the warning coordination meteorologist at 808-973-5275.
Additional resources:
see /in lowercase/ http://www.Prh.NOAA.Gov/hnl/pages/marine.Php
$$
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