Swell Energy Profile (also known as Spectral Density): This graph depicts the distribution of energy hitting the buoy during the sample time for all the frequencies/periods. Energy is depicted in feet. Think of this NOT as a time-lapse image for identifying whether the swell is increasing or decreasing, but rather as a snapshot that indicates the presence of one or more swells converging at the buoy at a single instant in time. It's is best used to identify real swell hidden under shorter period chop. Small amounts of long period energy are far more rideable and powerful than larger quantities of short period energy. Look for spikes or peaks in energy towards the left hand end of the graph (periods greater than 10 secs), then plan your surf session around finding breaks that best focus that energy.
Sea Height or Combined Sea Height (also known as Significant Seas): This is the summation of all the energy (greater than or equal to 5.88 seconds) at the buoy during the sample window. It is a rough approximation of the height of the highest 1/3 of all waves that passed under the buoy. Individual waves up to twice this size could occur once every hour.
Primary Swell Height: The size (in feet from the trough to crest) of the largest 1/3 of swells present at the buoy. Remember, smaller swells with longer periods often result in larger waves than seemingly bigger waves that have short periods.
Primary Swell Period: The composite period (in seconds) of the largest swell.
Primary Swell Direction: The composite direction the primary swell is coming from. This information is provided when available. Not all buoys provide directional data.
Surf Height: This is calculated using combination of primary swell height and period in conjunction with our proprietary formula for determining surf height. The resulting surf height figures should be interpreted as follows: The first number represents the face height of the average set wave (highest one third of all waves). The second figure represents the largest set waves one would typically expect to see. Read this figures like: Normal sets will be XX ft with occasional sets to XX ft. Larger waves still are possible and likely once every hour.
Surf Height is not specific to any particular break. It represents the size of the average set wave at a theoretical break that has neither anything to reduce the size of the swell or enhance it. Things that can reduce swell size include (but are not limited to) obstructions that prevent a swell from proceeding straight towards the beach, like islands, points or anything that causes the swell to wrap or change direction. Offshore shoals, reefs or sandbars can cause the swell to drag on the bottom and loose energy, reducing size too. Conversely, certain ocean bottom configurations enhance wave size like: deep water trenches that deposit a swell onto a shallow reef. In short, use this data in combination with your local knowledge of the breaks near where you surf to determine what location will be best suited for your skills.
Surf heights for buoys located well off the coast (100 nmiles or more) are calibrated to estimate surf height at the beach closest to the buoy. Note: Swells that hit such buoys are not necessarily heading towards the closest beach, or any beach. If the swell is heading to the beach, it may take considerable time to reach the coast (4-36 hours, depending on buoy location). Use these heights with caution.
Primary, Secondary and Tertiary Swell/Period: All frequencies equal to or greater than 5.88 seconds are analyzed. The energy present at these frequencies are scanned using pre-established grouping widths to isolate spikes or pockets of energy that have a high probability of being ridden. The grouping widths are strictly established to minimize contamination from other swells. A composite period is computed for each group. Each group is ranked by it's height and period, and the three largest groups reported.
Additional weather data from the buoys are provided direct from NOAA/NDBC and CDIP without analysis by Stormsurf. Such data includes: Combined Sea Height (same as Sea Height above but includes all frequencies), Dominant Period (the frequency that reports the most energy) and Wind and Water data (self explanatory).