SURF ZONE FORECAST
NATIONAL WEATHER SERVICE HONOLULU HI
400 AM HST FRI JUL 25 2014
400 AM HST FRI JUL 25 2014
Surf along south facing shores will be 1 to 3 feet today, and then build to 2 to 4 feet on Saturday.
Surf along west facing shores will be 1 to 3 feet through Saturday.
Surf along east facing shores will be 2 to 4 feet through Saturday.
Surf along north facing shores will be flat to 1 foot through Saturday.
Outlook through Thursday July 31: trade winds will continue to produce short-period choppy surf along east-facing shores. Small, mainly background southerly swells are expected today, and may increase slightly over the weekend. No other significant swells are expected.
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 WED JUL 23 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: steady easterly windswell with minimum on Saturday and a slight uptick for southern shores by Sunday.
Detailed: mid Wednesday on eastern shores has heights near the trade windswell average. Heights should be a notch higher on Thursday.
Upper level ridging in the mid latitudes to the N to NE of Hawaii is keeping surface high pressure near 1030 mb anchored near 42°N, 155°W 7/22-24. This has allowed moderate to fresh trades over and well to the E to NE of Oahu. In turn, short-period surf from these winds has picked up 7/23 from within 60-90 degrees. Surf should peak on Thursday from this wind event.
Models show upper level troughing taking over to the NNE of Hawaii over the mid latitude zone Friday into mid next week. This feature would weaken the surface high pressure and thus the trades over and E to NE of Oahu starting 7/25. This decline in ocean surface winds is estimated to give way to a minimum in surf from windswell for Saturday into Sunday morning. Tropical influence could help to trend up the surf into Monday.
The tropics centered on about 12°N over a long zonal band from S of Hawaii eastward over 1000 nm have been in an active convective pattern. It is modelled to continue active into next week. These elusive small scale low pressure cells can affect the local winds. However, specifics are not well modelled beyond a few days. Thus, uncertainty is high for the Sunday, Monday, and long range wind and windswell forecast. Stay tuned for updates.
Mid Wednesday on northern shores has refracting windswell breakers for select locations while most surf zones are flat. Similar conditions are predicted for Thursday.
No surf is expected beyond tiny from W to NNE 7/24-28.
Mid Wednesday on southern shores has surf a pinch under the average summer surf levels at top spots. Similar surf is likely for Thursday.
The pacioos/cdip nearshore buoy off SW Oahu shows arrival of swell from various sources. This mix of episodes is expected to continue through the period with surf near average summer levels or less.
Trades in the southern hemisphere should keep steady, short-period surf of 8-11 seconds from 140-170 degrees through the period.
Longer period swell should be dominant from 190-210 degrees. The Barbers Point buoy shows low, 18-22 second energy from this direction on 7/23. This can be hindcast to a deep low pressure area that tracked east near the antarctic ice sheet south of the Tasman sea and New Zealand 7/13-15. This background surf should hold into Friday with subtle ups and downs.
Weak low pressure tracked from the northern Tasman sea eastward north of New Zealand 7/13-15. Shorter period swell from 190-210 degrees from this source is likely in the mix locally 7/23 in the 14-16 second band. This minimal source should also hold about the same into 7/25.
Gales returned to the Tasman sea 7/18 filling a wide area west of New Zealand into 7/20. Long-period forerunners are due locally late Saturday, with this event peaking on Sunday 7/26 at heights near or less than the summer average centered on 210 degrees.
Into the long range, jet stream troughing and a host of broad surface low pressure cells began to dominant the region E to SSE of New Zealand to SSW of French Polynesia starting 7/21 and is modelled to stay active to roughly 7/29. The initial days 7/21-22 had gales with a narrow fetch due to proximity to New Zealand. This source centered on 195 degrees is predicted to fill in locally Tuesday 7/29 at continued average to below average levels. Models suggest better potential for the unfolding pattern downunder 7/24-29, that could see at least a few days topping the average summer levels from 180-200 degrees within about 7/31-8/5.
Active tropics in the north Pacific from Mexico to the philippines will be monitored for potential surf. There are no specifics on 7/23.
July 24 is the climatological minimum for northern shores. Typhoon activity in the western north Pacific is the most common source for trending up the surf into the new season.
Models are showing moderate to fresh trades trending up 7/29-30 that should bring up the short-period surf a notch from 60-90 degrees.
Long range forecasts are subject to low confidence.
This collaborative forecast will resume on Friday, July 25.
This forecast was produced through the collaborative efforts of NWS and NCDDC. Please send suggestions to email@example.com 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|