6am OBS, Monday, April 21st
Few to scattered clouds with a couple of windward showers. Light to moderate East trades with sea breezes filling in for leeward coasts. No marine warnings.
Big Picture updated 4/20. Small North, SSW, & NE trade wind swells. New NW & South. Call 596-SURF: 7a, Noon, 4pm (recap-forecast).

North Shore:
Dropping 11 sec North + Rising Slow 15 sec NW + Dropping NE trade wind swell wrap. Nice, clean conditions due to a light offshore wind. Sunset 1-2'; Rocky Pt 1-2'; Pipe 1-2'; Chuns 1-1.5'; Laniakea 1-2'+; Ali'i Beach Park 1'. Scattered clouds.
West:
Dropping 14 sec SSW + Rising 18 sec South + Rising Slow 15 sec NW. Clean conditions for now but mushing out towards lunch as a sea breeze takes hold. Makaha is 1-occ. 2' and breaking inside the reef. Mostly clear skies.
Town:
Dropping 14 sec SSW + Rising 18 sec South. Clean conditions due to breezy trade winds. Waikiki reefs are 1-occ. 2'; Kaisers-Rockpiles to Ala Moana to Kewalos are 1-2' occ. +. Mostly clear skies.
Diamond Head:
Dropping 14 sec SSW + Rising 18 sec South + Dropping trade wind swell wrap. Ruffled and bumpy due to breezy sideshore trades. Surf's 1-2' occ. + at takeoff. Few clouds.
Sandy's:
Dropping 14 sec SSW + Rising 18 sec South + Dropping NE trade wind swell wrap. Full Pt/Half Pt are 1-2'+ and a tad bumpy. Shorebreak is also 1-2'+ on the mixed plate, cleaner than the reefs and nice sandbar peaks. Few clouds.
East Makapu'u:
Dropping 8 sec NE trade wind swell + Dropping 11 sec North. A little bumpy and mushy due to moderate East trades. Surf's 1-2'+ on the shorebreak spread out across the bay. Scattered clouds.Winds
5-15+mph East Trade
Leeward seabreezes afternoon
5-10mph SE
Seabreezes afternoon
5-15mph SSE
Seabreezes afternoon
5-10mph SE
Seabreezes afternoon
5-15mph ESE
North
Primary

Haw: 1-2
Face: 1-3
Secondary
Rising Slow 15s NWHaw: 0-1.5
Face: 0-2
Fair to good
2' afternoon
Primary
Up & holding 13s NWHaw: 1-2
Face: 1-3
Secondary
None NONEHaw: 0
Face: 0
Fair to good
Primary

Haw: 1-2
Face: 1-3
Secondary
None NONEHaw: 0
Face: 0
Good offshores
Primary

Haw: 1-1.5
Face: 1-2
Secondary
None NONEHaw: 0
Face: 0
Good offshores
Primary

Haw: 0-1.5
Face: 0-2
Secondary
None NONEHaw: 0
Face: 0
divin , paddlin, fishin, sailin
West
Primary

Haw: 0-1.5
Face: 0-2
Secondary

Haw: 1-2
Face: 1-3
Fair to good
Primary
Up & holding 13s NWHaw: 0-1.5
Face: 0-2
Secondary
Up & Rising 18s SHaw: 0-1.5
Face: 0-2
Fair to good
Primary
Up & holding 16s SHaw: 1-2
Face: 1-3
Secondary

Haw: 0-1.5
Face: 0-2
Smoother early-mushier midday
Primary

Haw: 0
Face: 0
Secondary

Haw: 0-1.5
Face: 0-2
Good offshores
Primary

Haw: 0-1.5
Face: 0-2
Secondary

Haw: 0-1
Face: 0-1.5
Mushy
South
Primary

Haw: 1-2 occ +
Face: 1-3 occ +
Secondary

Haw: 1 occ 2
Face: 1-2 occ 3
Fair
Primary
Up & Rising 18s SHaw: 1-2 occ 3
Face: 2-4 occ 5
Secondary
None NONEHaw: 0
Face: 0
Mushy
3'+ late afternoon
Primary
Up & holding 16s SHaw: 2-3 occ +
Face: 3-5 occ +
Secondary
None NONEHaw: 0
Face: 0
Smoother early-mushier midday
Primary

Haw: 1-2 occ 3
Face: 2-4 occ 5
Secondary
None NONEHaw: 0
Face: 0
Smoother early-mushier midday
Primary

Haw: 1-2 occ +
Face: 1-3 occ +
Secondary

Haw: 1-1.5
Face: 1-2
Mushy
east
Primary

Haw: 1-2+
Face: 1-3+
Secondary

Haw: 1-2
Face: 1-3
Mushy
Primary

Haw: 1-2
Face: 1-3
Secondary

Haw: 1-1.5
Face: 1-2
Good early , fair later
Primary

Haw: 1-1.5
Face: 1-2
Secondary
None NONEHaw: 0
Face: 0
Smoother early-mushier midday
Primary

Haw: 1-1.5
Face: 1-2
Secondary
None NONEHaw: 0
Face: 0
Smoother early-mushier midday
Primary

Haw: 1-1.5
Face: 1-2
Secondary
None NONEHaw: 0
Face: 0
Smoother early-mushier midday

Current Swells:
Monday 04/21Primary: Dropping 8s NE surf @1-2+
Secondary: Dropping 14s SSW surf @1-2 occ +
Third: Dropping 11s N surf @1-2

Marine Warnings:
Monday 04/21None

Sailing Report:
Monday 04/21Fair due to light to moderate+ E-ENE trades then onshore sea breezes midday to afternoon for Leeward coasts.

Diving Report:
Monday 04/21North shores: Fair to good diving conditions for most zones due to fading North swell and offshore trades (Good for deeper dives). West: Good for most zones due to tiny to small surf. South: Fair-good esp. for deeper zones with small surf and lite to moderate trades early with poss seabreezes near lunch. East: Fair for most zones due to onshore trades and small surf.
Oahu
Maui
Kauai
Big Island
Weather
Surf Advisory and Warning CriteriaLocation/shoreline Advisory Warning
North-Facing Shores- 15 Feet faces (8' Local) 25 Feet faces (15' local)
West-Facing Shores - 12 Feet (7' local) 20 Feet (12' local)
West-Facing- Big Is.- 8 Feet (4'+ local) 12 Feet (7' local)
South-Facing Shores- 8 Feet (4'+ local) 15 Feet (8' local)
East-Facing Shores- 8 Feet (4'+ local) 15 Feet (8' local)
Big Picture
INACTIVE.Get the latest on the tropics at www.hurricanes.gov
The Central Pacific Hurricane Center outlook for the 2017 Central Pacific Hurricane Season calls for 5 to 8 tropical cyclones to either develop or cross into the Central Pacific with a 40% chance for an above-normal season, a 40% chance for a normal season, and a 20% chance for a below-normal season. An average season has 4 to 5 tropical cyclones, which include tropical depressions, tropical storms, and hurricanes.
A tropical depression forms when a low-pressure area is accompanied by thunderstorms that produce a circular wind flow with maximum sustained winds below 39 mph. An upgrade to a tropical storm occurs when cyclonic circulation becomes more organized and maximum sustained winds gust between 39 mph and 73 mph. A tropical storm is then upgraded into Category 1 hurricane status as maximum sustained winds increase to between 74 mph and 95 mph. (The highest classification in the scale, Category 5, is reserved for storms with winds exceeding 156 mph).
Tropical cyclones go by many names around the world, and the terminology can get confusing. Once a tropical cyclone strengthens to the point where it has gale-force winds—39 mph or greater—it becomes a tropical storm. A storm that reaches tropical storm strength usually gets its own name to help us quickly identify it in forecasts and warnings. Once a tropical storm begins producing sustained winds of around 75 mph, we call the storm a typhoon in the western Pacific near Asia and a hurricane in the oceans on either side of North America. A “typhoon” and a “hurricane” are the same kind of storm, they just go by different names…it’s only a matter of geography.
NWS criteria for High Surf Advisories & Warnings.
In coordination with civil defense agencies & water safety organizations in Hawai`i, the NWS uses the criteria below for the issuance of High Surf Advisories & Warnings in coordination with civil defense agencies & water safety organizations in Hawai`i.
All surf height observations & forecasts are for the full face surf height, from the trough to the crest of the wave.
Advisory and Warning Criteria Location
Warning North-Facing Shores 15 Feet 25 Feet
West-Facing Shores - Remaining Islands 12 Feet 20 Feet
West-Facing Shores - Big Island 8 Feet 12 Feet
South-Facing Shores 8 Feet 15 Feet
East-Facing Shores 8 Feet 15 Feet
'Travel Time' Buoy 51101 to Waimea Buoy. Distance: 269 nautical miles (~310 miles). Angle: 307 deg
Wave Wave Wave Depth Wave Direction (deg)----------
Period Length Speed Shallow 295, 305, 315, 325, 335, 345, 355
(s) (ft) (nm/h) (ft) Travel Time (hours)----------
10sec. 512. 15. 256. 17.3, 17.7, 17.6, 16.9, 15.7, 14.0, 11.9
12sec. 737. 18. 369. 14.5, 14.8, 14.6, 14.0, 13.0, 11.6, 9.9
14sec. 1003. 21. 502. 12.4, 12.7, 12.5, 12.0, 11.2, 10.0, 8.5
16sec. 1310. 24. 655. 10.8, ,1 1.1, 11.0, 10.5, 9.8, 8.7, 7.4
18sec. 1658. 27. 829. 9.6, 9.8, 9.8, 9.4, 8.7, 7.8, 6.6
20sec. 2047. 30. 1024. 8.7 8.9 8.8 8.4 7.8 7.0 5.9
22sec. 2477. 33. 1239. 7.9 8.1 8.0 7.7 7.1 6.3 5.4
24sec. 2948. 36. 1474. 7.2 7.4 7.3 7.0 6.5 5.8 4.9
Tropical Storms - wind 39-73 mph (34-63 kt)
Category 1 - winds 74-95 mph (64-82 kt)
Category 2 -winds 96-110 mph (83-95 kt)
Category 3 -winds 111-130 mph (96-113 kt)
Category 4 - winds 131-155 mph (114-135 kt)
Category 5 -winds 156 mph and up (135+ kt)
Please visit the Central Pacific Hurricane Center website at www.weather.gov/cphc for the most recent bulletins.
ENSO is a single climate phenomenon, it has three states or phases. The two opposite phases, “El Niño” and “La Niña,” require certain changes in both the ocean and the atmosphere because ENSO is a coupled climate phenomenon. “Neutral” is in the middle of the continuum. The MJO (Madden-Julian Oscillation) is an eastward moving disturbance of clouds, rainfall, winds, and pressure that traverses the planet in the tropics and returns to its initial starting point in 30 to 60 days, on average, unlike ENSO which is stationary. In a nutshell, more active means more surf.
Kelvin wave (A Kelvin wave is a wave in the ocean or atmosphere that balances the Earth's Coriolis force against a topographic boundary such as a coastline, or a waveguide such as the equator. A feature of a Kelvin wave is that it is non-dispersive, i.e., the phase speed of the wave crests is equal to the group speed of the wave energy for all frequencies. This means that it retains its shape as it moves in the alongshore direction over time.)
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