Johnshaven ratings
Quality on a good day: 4.0
Consistency of Surf: 2.0
Difficulty Level: 3.0
Crowds: 4.0

See all 18 ratings

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Surf Report Feed

Johnshaven Swell Statistics, August: All Swell – Any Wind

The rose diagram shows the combination of swells directed at Johnshaven over a normal August, based on 1984 NWW3 model predictions since 2006 (values every 3 hours). The wave model does not forecast surf and wind right at the coastline so we have chosen the optimum grid node based on what we know about Johnshaven. In this particular case the best grid node is 31 km away (19 miles).

The rose diagram shows the distribution of swell directions and swell sizes, while the graph at the bottom shows the same thing without direction information. Five colours illustrate increasing wave sizes. Blue shows the smallest swells, less that 0.5m (1.5 feet) high. These were forecast only 63% of the time. Green and yellow illustrate increasing swell sizes and red illustrates the biggest swells, greater than >3m (>10ft). In each graph, the area of any colour is proportional to how often that size swell was forecast.

The diagram indicates that the prevailing swell direction, shown by the largest spokes, was SSE, whereas the the prevailing wind blows from the SW. Because the wave model grid is offshore, sometimes a strong offshore wind blows largest waves away from Johnshaven and away from the coast. We group these with the no surf category of the bar chart. To keep it simple we don't show these in the rose graph. Because wind determines whether or not waves are clean enough to surf at Johnshaven, you can select a similar diagram that shows only the swells that were expected to coincide with glassy or offshore wind conditions. During a typical August, swells large enough to cause surfable waves at Johnshaven run for about 8% of the time.

IMPORTANT: Beta version feature! Swell heights are open water values from NWW3. There is no attempt to model near-shore effects. Coastal wave heights will generally be less, especially if the break does not have unobstructed exposure to the open ocean.

 

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