surf zone forecast
National Weather Service Honolulu HI
700 PM HST Fri Nov 20 2009
hiz005>011-211900-
Oahu-
700 PM HST Fri Nov 20 2009
Surf along east facing shores will be 4 to 6 feet through Saturday.
Surf along north facing shores will continue at 4 to 7 feet through
Saturday.
Surf along west facing shores will remain 1 to 3 feet through
Saturday.
Surf along south facing shores will be 2 to 4 feet through Saturday.
Outlook through Thursday Nov 26:
a large northwest swell is expected to begin filling in Saturday
night...likely reaching advisory levels Sunday and Monday then
slowly lowering into Tuesday. A larger northwest swell is expected
to fill in Tuesday night...and peak late Wednesday or Wednesday
night.
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 Thu Nov 19 2009
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 N 11 6 10 same 17-21 ENE same
11/19 8 ENE 8 4 6 down
2 SSW 14 2 4 same
Fri 4 NNE 10 6 8 down low 17-21 ENE same
11/20 8 ENE 8 4 6 same Med
2 SSW 13 2 4 same low
Sat 4 N 13 6 8 up low 17-21 E same
11/21 8 E 8 4 6 same Med
2 SSW 13 2 4 same low
Sun 7 NW 18 14 18 up high 17-21 E down
11/22 8 E 8 4 6 down low
2 SW 16 2 4 up low
Mon 8 NNW 16 16 20 down high 11-16 ENE same
11/23 6 E 8 2 4 down low
2 SW 15 2 4 same low
Tue 6 NNW 14 10 12 down low 11-16 ENE same
11/24 6 E 8 2 4 same low
2 SSW 14 2 4 same 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...
return to seasonal high surf on North Shores on Sunday.
Detailed...
mid Thursday on northern shores has sub-moderate breakers from
345-020 degrees with 8-14 second periods. It was generated by near
gales to gales from a system centered on about 145w to the NNE of
Hawaii on Monday into Tuesday. This episode should favor small
levels on Friday from 350-020 degrees.
A reinforcement low pressure system formed on the west side of the
existing low pressure area to the NNE of Hawaii also centered on
about 145w bringing more near gales to marginal gales aimed at
targets east of Hawaii over the past 24 hours. Angular spreading
could bring in sub-moderate breakers on Saturday from 000-030
degrees...dropping on Sunday.
The blocking ridge over the northwest Pacific shifted east enough to
allow a storm- to hurricane-force system into the open waters off
the northern Kuril Islands and Kamchatka over the past 48 hours. The
centered tracked to the NNE during the first 24 hours starting late
Tuesday...across the great Circle rays relative to Hawaii...which
reduces surf potential by shortening the duration. By late
Wednesday...the tracked turned more NE as it broadened...allowing a
longer apparent fetch. This track is similar to the system that
produced the Halloween weekend surf that went well into the
extra-large bracket. In comparing Quikscat data for that one versus
this one...the previous one had a longer fetch with slightly
stronger winds. None-the-less...marginal extra-large surf is
expected to slowly build locally on Sunday...with forerunners
filling in Saturday night from 310-325 degrees. The episode should
peak Sunday night into Monday morning from 315-325 degrees. It
should slowly fade below high surf levels sometime on Tuesday from
320-340 degrees.
Mid Thursday on Eastern Shores has moderate to marginally high
breakers...especially for zones exposed to the the northerly
component swell as described above. More of the same is expected
into Saturday as local trades remain fresh. A downward trend in surf
and wind for windward shores is expected on Sunday...except for
locations exposed to refracting long-period swell from the NW.
Moderate trades are expected Monday into Tuesday with small breakers
from 45-90 degrees.
Mid Thursday on Southern Shores has tiny to small breakers...down
from recent days. More of the same is expected through the period.
A storm-force low pressure system in the southern Tasman Sea last
weekend could bring in a small episode from 208-220 degrees this
Sunday into Monday.
Into the long range...tiny to small surf for Southern Shores next
week. Models suggest a small to moderate episode from a New Zealand
system arriving around November 29...and another about 5 days later.
In the northern hemisphere...models depict a regime change with the
dateline ridge giving way to a trough...and an overall southward
shift to the track over most of the North Pacific...bringing systems
closer to Hawaii and increasing the surf size. A severe gale is
modelled to nose within 1000 nm of Hawaii by Monday...bringing
extra-large surf locally on Wednesday from 320-340 degrees. Winds
are expected to vary day to day as the weather systems pass north of
the islands...with some days of moderate trades and others mostly
light and variable.
Long range forecasts are subject to low confidence.
This collaborative forecast will resume on Monday...November 23.
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
$$
NWS cp/ncddc pat Caldwell
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