SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST SUN MAR 9 2014
400 PM HST SUN MAR 9 2014
Surf along north facing shores will diminish to heights of 6 to 10 feet tonight, and 5 to 7 feet Monday.
Surf along west facing shores will diminish to heights of 4 to 8 feet tonight and 2 to 4 feet Monday.
Surf along east facing shores will be 2 to 4 feet through Monday.
Surf along south facing shores will be 2 to 4 feet through Monday.
Outlook through Saturday March 15: a moderate northwest swell will build Tuesday and peak Wednesday with surf heights approaching advisory levels along north facing shores. A larger northwest swell will arrive Thursday, build through Friday, and peak on Saturday with surf heights reaching advisory levels along north and west facing shores.
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 7 2014
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: above average surf for north shores over the weekend.
Detailed: mid Friday on northern shores has small breakers from 320-360 degrees with 9-15 second periods. A new episode is rising.
The source for the building surf on Friday 3/7 was two-tiered. Gales behind a front pushed east from the dateline Tuesday nosing to near 1200 nm away from Hawaii on Wednesday. Buoy 51101 WNW of Kauai shows a rise in 12-15 second energy after 3 am 3/7. The Waimea buoy is trending up mid Friday. This phase of the new episode should rise to high levels near sundown on Friday. Overnight, a larger pulse is due.
The second aspect for wave generation took place starting Tuesday just west of the dateline, where a surface low pressure deepened near 45°N. Surface winds were strongest late Tuesday through early Thursday with a short fetch of severe gale to storm-force speeds over the 310-325 degree band. The low center tracked SE on Wednesday, which gave more apparent fetch length to the maximum winds. Once east of the dateline, the wind maximum steadily weakened. The overall pattern kept a steady eastward path, leaving the Hawaii swell window mid Friday 3/7. Relative to earlier weather model runs from 3/4-5, the nose of the strongest winds and gales did not reach as close to Hawaii as eventually unfolded. The GFS and the navgem input to the Wave Watch III both noted a downward trend in expected deep water swell off Hawaii for the peak of the episode. This 3/7 forecast has reduced the expectations a notch relative to 3/5. However, the source is strong enough to make above winter average surf.
Buoy 51101 is showing a rise in the longer wave periods of 15-19 seconds late morning 3/7. This is the start of the second pulse. Surf should build locally overnight Friday, reaching extra-large levels, meaning breakers on outer reefs, by sunrise Saturday from 310-325 degrees. The event is expected to peak in the early afternoon Saturday, then drop to within high to extra-large by Sunday morning from 305-330 degrees. Heights should steadily fall late Sunday into Monday, down to within small to moderate heights from 310-340 degrees.
Models show a deepening surface low pressure near the dateline at 40°N on Saturday night, tracking NE to 50°N, 160°W near the Aleutians by Monday as it reaches storm force. The primary wave generation is predicted to be aimed at targets NE of Hawaii since the low center track is across the great circle rays relative to Hawaii. This source should bring in a moderate event, building late Tuesday and peaking near dawn on Wednesday from 315-330 degrees.
Mid Friday on eastern shores has flat conditions from 60-90 degrees. An increase is expected on Saturday.
A front is due to track over Oahu Friday afternoon 3/7 into the evening, as the local winds veer from west to north. A surface high pressure near 30°N on the dateline Friday 3/7 is modelled to be N of Hawaii on Saturday 3/8, veering the winds from NE in the morning around to ENE in the evening. A short-lived fresh trade wind event is modelled, centered on Saturday night, too short a duration and not long enough an upstream fetch to make significant windswell. Small breakers are expected to pick up Saturday afternoon from 30-60 degrees and remain small from 50-80 degrees on Sunday.
The low pressure source for the upcoming Tuesday night swell is expected to weaken the high north of Hawaii on Monday, with dropping trades to within gentle to moderate 3/10. A new high pressure is modelled to build east on Tuesday, bringing another short-lived, fresh trade wind event centered on Wednesday night. Windswell should build to small levels on Wednesday.
Mid Friday on southern shores is near flat. Similar conditions are expected on Saturday.
Typhoon Faxai east of Guam 3/2-4 was too far away and too compact to expect any surf locally beyond tiny, which could pick up Sunday into Monday from 270-280 degrees.
There was a tropical cyclone NE of New Zealand last weekend 3/1 though it moved SE, putting minimal surf aimed at Hawaii. No surf is expected from this source.
Into the long range, the SW Pacific tropical cyclone merged with a mid latitude low to the east of New Zealand 3/4, with a wide area of severe gales forming. This fetch aimed best at targets W of Hawaii on 3/5. As the fetch turned more towards Hawaii on 3/6, the wind speeds gradually weakened. It could be enough for a small, long-period episode locally, picking up late Wednesday 3/12, peaking late Thursday 3/13, and slowly dropping into 3/15 from 185-195 degrees.
In the northern hemisphere, models deepen a surface low pressure to storm-force near 40°N east of northern Japan late Monday, reaching the dateline as it weakens Wednesday, and tracking east across 160°W north of Hawaii next Friday. Long-period surf from 300-315 degrees should build on Friday 3/14 to high levels, with added energy from 315-350 degrees by Saturday 3/15. Models suggest a front with fresh northerly winds locally arriving next Friday, so this event make for disorganized conditions 3/14, slowly cleaning up 3/15.
Trades are expected to decline Thursday into Friday with small windswell from 60-90 degrees.
Long range forecast are subject to high uncertainty.
This collaborative forecast will resume on Monday, March 10.
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|