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Introduction / Uncertainty? / Probability winds


The National Blend of Models (NBM) Oceanic domain is an interesting weather model.

This model is a blend of many other weather models. See the NBM Oceanic page for more details.

While ensemble models, such as GEFS, create the average (mean) and standard deviations, NBM Oceanic creates probability winds. By examining the range of wind values at each point, among its large number of input models, it can determine the spread of values and assign probabilities to them according to how the input models are grouped.

The model ends up with 5 wind strength values. Here is an example for the winds available at a point:

Recall from the introduction to this Uncertainty section that the LG weather router is able to create solutions using both 10m wind speed and wind gust. When you create routes using NBM Oceanic, the solver will create every possible combination of wind direction and wind speed that is contained in the file.

Returning to the first example from the previous sections again, here are the solutions when run with the NBM Oceanic data:

As with each previous example for this passage, the portion from the start point to around Cornwall is pretty consistent, and then the paths diverge. This is another good example for how the system can show you a range of possibilities.

Note, if you were at sea downloading weather, this model is one of the candidates you should consider. You may not need all probabilities, perhaps the mean value and then the 25% probabilities on each side?

Returning to the examples from the ensemble section, here are the routes between Los Angeles and Puerto Vallarta using NBM Oceanic winds.

Los Angeles to Puerto Vallarta.
Puerto Vallarta to Los Angeles.

The Los Angeles to PV routes have durations from 6 days 20 hours to 9 days 4 hours. The most southerly route shown is for the 10% chance winds less than wind field, which is the lightest winds in this model. The median wind field is in the middle of that pack.

The image on the right, for the reverse route, does indeed have five paths. They are a close match, which as a navigator, would be a nice result to see.


LuckGrib Weather Routing is currently only available on macOS. Support for iOS and iPadOS is under development.