Greetings
Before you reach the TOC the FMS would have computed data in order to elaborate a type of atmosphere through which your flight is taking place, and this is done for the PREDICTIONS, 5D predictions in fact, lat, long. altitude, time, and finaly FUEL.
If you didnot enter any wind in the cruise segment of the flight, the FMS will assume that the wind is calm = 0 kts, so he will compute a blended wind using the actual, averaged with the entered wind in our case 0, he will then use a percentage of the above and mix it with the actual wind using a percentage for "dilution" this percentage is based on a distance between the aircraft position and the next waypoint where a wind is supposed to be enetered, in our case 0 again. SO to cut it short at 100 nm he will use 100% of the actual wind, at 90 nm, he will use 90% actual wind weighted with 10 of the blended wind at 80 nm he will use 80% and so on..
If you have used history wind, then the fms will propagate it fom TOD to TOC and use it as decribed below (in stead of calm i.e., 0 the FMS will use the wind closest to you CRZ level in the history wind list)
