Seeing two winds charts is like getting a second opinion. If there is consensus between the forecast models there is a higher degree of confidence those conditions will prevail.

The BOM and GFS models are independent. They are produced by different agencies and have different model physics so when they arrive at the same conclusion you can be more confident the forecast will be correct.

If the models differ on any given day and one says strong winds while the other says low winds then there is little consensus and therefor lower confidence in an accurate forecast on that day.

The BoM model is the model we have always used and is the model used by Meteye and Willyweather. GFS is the model used by many other weather sites including Windfinder, Buoyweather, Windy, WindGuru and others. In most parts of Australia the BoM model will be more accurate but there some areas where GFS may prove more reliable. Users should observe both over a period of time and determine which performs better at their location.

Technical Information
The BoM (ADFD) model has a resolution of 3km in VIC & TAS and 6km in other states, it covers Australia out to a distance of 60nm from shore. The GFS model has a resolution of 9km and covers the entire globe.

Note: In June 2019, thanks to a 10 fold increase in computing power, NOAA who produce the GFS upgraded the model to a high performance FV3 version. This change increased resolution from 13km down to 9km and improved model physics. FV3 is the version used by Fish Ranger.

Wondering why we don't we use the ECMWF 9km model? The BOM model is based on the 'EC' model so they have very similar model physics and are not independent. By showing BOM and GFS models we can present two high quality independent forecasts.

We use bilinear interpolation to provide forecasts true to the chosen location, be they on sea or land.

What is Solunar?

Solunar Theory is a hypothesis that states all wildlife have periods of heightened physical activity that correspond with the relative locations of the sun and the moon. The theory was published by John Alden Knight in 1936 after years of documented and anecdotal research from hunters and fishers. The name Solunar comes from ‘Sol’ for sun and ‘Lunar’ for moon.

The theory found that aside from tides, the relationship of the moon and sun’s position also affected fishing effectiveness. When the moon is directly overhead or underfoot, rising or setting, fish are more likely to feed than at other times of the day. If one of these periods occurs close to sunrise or sunset then feeding activity is higher again, and if the moon is in a new or full phase then the highest activity of the month can be expected.

Major periods are defined as one hour each side of when the moon is directly overhead or underfoot, minor periods are defined as one hour each side of when the moon is rising or setting. The Solunar Calendar allows fishermen to better predict what days of the month and what times of the day fish are more likely to be feeding.

One experiment that supported the theory was when Dr. Frank A. Brown, a biologist at Northwestern University in USA, had some live oysters flown to his lab near Chicago. Oysters open their shells with each high tide, and Dr. Brown wanted to see if this was due to the change in ocean levels or to a force from the moon itself. He put them in water and removed them from all sunlight. For the first week they continued to open their shells with the high tides from their ocean home. But by the second week, they had adjusted their shell-openings to when the moon was directly overhead or underfoot in Chicago.

Solunar tables need to be used along with common sense. Not every day will there be a clear relationship between fish biting and major or minor periods as other factors are involved which affect a fish’s willingness to feed. Barometric fluctuations, particularly when the trend is down, often make for poor fishing. All wildlife knows what to expect of the weather, and any bird, animal or fish can sense the approach of a storm. Cold fronts moving through drive fish deeper and render them inactive.

Adverse temperature, abnormal water conditions, and other factors all need to be considered as these offset the effects of major and minor periods, but when other factors are constant the Solunar calendar can be a good guide to identify better fishing days and times.

Fish Ranger’s Solunar Calendar is calculated individually for each location using precise sun and moon positions and all times are pre-adjusted for daylight savings so you can use the calendar with confidence and ease.