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Background: The spectral bulletins are a breakthrough in swell forecasts created by the geniuses at the NOAA Ocean Modelling Branch. What makes the bulletins unique is that they track up to six concurrent swells for each forecast time. The BuoyWeather decoder program makes the data a little more readable and adds a swell to surf conversion.
How To Read: The sample above shows the header and just one forecast day. The full report starts with a 6 hour hindcast and will go out at 6 hour intervals for seven days. For each time shown on the left, there will be up to six concurrent swells listed by their general directions. For example, above shows five swells in Hawaii on the 10/24 at 2am. One west swell, one north, two from the east, one from the south. All of these swell are crossing this point at the same time.
Each swell is characterized by five variables:
- Swell Height(feet) - The average of the heighest 1/3 waves. This is an average and may not be the highest you'll see.
- Swell Direction(degrees) - Peak direction of each swell in degrees.
- Peak Period(second) - The interval between wave crests measured in seconds. Large, Short period swells mean danger to boaters. Long period swells mean opportunity for surfers.
- Average Surf (feet) - The first number is the surf face forecast calculated by height X period X .12 . This is only valid when there is a nearby shore line directly exposed to the swell direction indicated. Check the direction carefully, It may not a be pointing toward shore or may be blocked by a point or island.
- Peak Surf- The second number is Average Surf Height X 1.5 . This is the statistical "wave of the day". You may not always see this, but it will happen on some swells. This gives you the upper end potential for the surf.
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