Methodology

How theviz turns weather history into a visibility forecast

The model is designed around a simple observation: calm water today does not necessarily mean clear water today.

1. Offshore swell and weather

theviz reads multiple global wave and atmospheric models. It uses significant wave height, period and direction, as well as wind and rainfall-related context, rather than relying on a single source or a single headline swell figure.

2. Site-specific exposure

Each named site has an exposure geometry. The model estimates how much offshore wave energy reaches that location, accounting for direction, shelter and the greater ability of long-period swell to wrap around headlands.

3. Bottom stirring and settling

Waves that reach the seabed can mobilise sediment. theviz estimates near-bottom wave motion, accumulates recent stirring, and lets the suspended load decay over a site-specific settling period. This gives the forecast memory.

4. An ensemble, not a single claim

Each weather-model combination and plausible site parameter set is run separately. theviz then reports a median, a 10th–90th percentile range and threshold probabilities. A wide range is useful information: it means the inputs or the site response remain uncertain.

5. Separate clarity from safety

Visibility is not a safety score. Entry/exit, surge, wind, surface chop and current are evaluated separately; a good clarity estimate never overrides a limiting condition.

Limitations

theviz does not directly model every local process, including site-scale currents, stormwater plumes, plankton blooms, thermoclines or detailed bathymetry. It is an aid to judgment, not a substitute for local observation, formal forecasts, marine notices or personal experience.