ECMWF (Black) ECMWF is the number one ranked global mode from a national weather agency, with a 9 km resolution globally.

Spire (Orange) Spire is the #1 ranked global model from a private weather company, often outperforming ECMWF in the open ocean, 25 km resolution globally.

UKMO (Yellow) UKMO is the number 2 ranked global model from a National weather service—a highly regarded model with 15 km resolution globally.

PWG (Blue) stands for the PredictWind weather model that uses the NCEP global initial conditions for the model run. The resolution available is 1km/8km/50km globally.

PWE (Red) is the PredictWind weather model that uses the European Center for Medium-Range Weather Forecasts global initial conditions. The resolution available is 1km/8km/50km globally.

GFS (Green) Global Forecast System from NCEP as this is used by most other weather websites/apps - 25 km resolution globally.

If you are looking at a 'coastal' route, the PWG/PWE forecasts are 1km (Professional Package) or 8km resolution (Standard Package) and will model the geographic/heating effects. The 9km ECMWF and 15km UKMO will pick up some of these effects but not as accurately.

For short-term decision-making, you should select the forecast that appears to be doing the 'best job' of matching the observations. You can use your boat data and data from the observations page in PredictWind.

In addition, try to understand if there is an apparent reason that the routing is going in a particular direction, i.e. is it due to wind direction or strength? Please watch the animation carefully. The weather routing is not an exact road map to follow, but a general trend, as the timing and placement of the weather pattern is never 100% accurate.

If there is a lot of uncertainty, the routes will be spread out, and it may be best to sail the fastest VMC along the course. But generally, the routes should line up for the first 12-24 hours. You should be updating the route with each new forecast every 12hrs. To check when the forecast updates, please review the FAQ.

The routing algorithm will find the best route based on your polar and the forecast. It looks at ALL the possible paths and selects the best route. However, it is only as good as your polar's forecast and accuracy. The forecast is an average of over 1 hour, but the forecast at the lower resolutions, 8km & 50km, is only output every 3 hours. So, the optimum route does not have the granularity to help with short-term wind shifts and variations in wind speed. So, you must decide how best to use the short-term gains over a 3-hour period. We recommend treating the optimal route as a general guide and fine-tuning it for the exact conditions you experience.

The best route is only as accurate as the forecast and the polar you have set. Please ensure you have correctly set up the polar, and the boat speeds shown in the results match your actual boat speeds.