SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST TUE APR 28 2015
400 AM HST TUE APR 28 2015
HIGH SURF ADVISORY FOR NORTH FACING SHORES TODAY AND
FOR EAST FACING SHORES THROUGH WEDNESDAY NIGHT
Surf along north facing shores will be 10 to 15 feet today, lowering to 8 to 12 feet Tuesday night, and 5 to 8 ft Wednesday.
Surf along east facing shores will be 6 to 9 feet through Wednesday.
Surf along west facing shores will be 3 to 5 feet through tonight, and 2 to 4 feet Wednesday.
Surf along south facing shores will be 1 to 3 feet through Wednesday.
Outlook through Monday May 4: strengthening trade winds will cause short period choppy surf to continue along east facing shores through most of this week. Small long-period background swell is forecast for south facing shores through the week.
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 MON APR 27 2015
This collaborative forecast will be updated Monday through Friday at 300 pm when Pat Caldwell is available.
|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.
Summary: north shores trending down as eastern shores remain elevated and rough through the week.
Detailed: mid Monday on northern shores has breakers above the September to may, seasonal average from 330-360 degrees with 8-16 second periods. Heights are predicted to lower overnight into Tuesday from 330-020 degrees.
Surf on Monday was produced by remote and nearby sources. A gale in the Bering Sea 4/21-24 had a fetch south of the Aleutian islands west of the dateline for the 325-335 degree band. As the system passed east of the dateline 4/22-23, an amplifying jet stream pushed a cold front to the SE, backed by near gales over the 330-345 degree band beyond 1200 nm away.
Closer to Hawaii, the amplifying jet pulled NE a surface low pressure from W to NW of Hawaii 4/24. It deepened the low to gale strength as it tracked NE past the longitude of Oahu late Saturday. The fetch aimed mostly at targets W of Oahu until Sunday. The NOAA buoy 51101, 270 nm WNW of Oahu, reached to 19 feet late Sunday. The nearby low has raced into the gulf of Alaska 4/27, east of the Hawaii swell window.
Proximity has allowed a sharp rise in surf and should also give way to a sharp fall, which is expected overnight Monday into Tuesday morning from 330-360 degrees. Below average surf from within 330-020 degrees should hold on Tuesday and drop to small levels on Wednesday.
Otherwise, refracting NE to E windswell should keep breakers for select north shores surf zones into the weekend. Surf from remote sources is expected to remain near nil.
Mid Monday on eastern shores has above average breakers for more northerly exposures as described above. Refracting northerly swell and building NE windswell is trending up more easterly exposures. Rough, above average surf is expected Tuesday.
A strong surface high pressure near 35°N, 170°W is moving east. It is modelled to stall to the NNE of Hawaii and hold through the week. Ascat satellite shows a fetch of strong breezes over the 30-50 degree band to the NE of Oahu out 600 nm late Sunday into Monday morning. As the high moves further east, the upstream fetch will veer on the compass more to 50-80 degrees. Thus, the dominant direction of the local surf should veer as well. By Thursday, the direction should settle within 70-90 degrees and hold into the weekend at above average levels, though with a downward trend.
Mid Monday on southern shores has below average surf from within 170-220 degrees. Similar conditions are expected on Tuesday.
Marginal gale systems south of French Polynesia 4/17-20 should add shorter-period, low surf from 170-180 degrees this week into Thursday while more polar regions in the zonal band from south of Tasmania to south of French Polynesia should add low, longer-period surf off and on from 180-220 degrees through the week.
Into the long range, a hurricane-force system with seas to 50 feet has tracked east to the SW of Easter Island 4/25-27. It is well east of the Hawaii swell window. Angular spreading could bring long-period breakers from 150-170 degrees late Saturday into Monday 5/2-4.
Models show a deepening low pressure system ESE of New Zealand 4/28 moving east, while a cold front pushes NE backed by gales to severe gales into 4/30, when the head of the fetch is predicted to be about 3500 nm away. This place the local onset day near Wednesday 5/6, being filled in by 5/7 from 185-200 degrees at levels above the seasonal average.
In the northern hemisphere, a zonal jet along the Aleutians is predicted to hold through the week, giving way to minimal surf from the NW to N 5/3-5.
Models suggest moderate to fresh trades and average ENE windswell 5/3-5.
Long range forecasts are subject to high uncertainty.
This collaborative forecast will resume on Wednesday, 3/29.
This forecast was produced through the collaborative efforts of NWS and NCDDC. Please send suggestions to firstname.lastname@example.org or call the Warning Coordination Meteorologist at 808-973-5275.
Additional resources: see /in lowercase/ http://www.prh.noaa.gov/hnl/pages/marine.php.
|Waimea Buoy||Kailua Buoy||Lanai Buoy||Barbers Point #2||Pauwela, Maui||Hilo Bay Buoy||Kaneohe Bay Buoy||Hanalei Kauai Buoy||Kilo Nalu||Buoy 51001||Buoy 51101||Buoy 51000||Buoy 51100||Buoy 51002||Buoy 51003||Buoy 51004|