I'd be reluctant to use forecast wind info to try to ascertain which of several disagreeing airspeeds (if any) might be correct. (I doubt there's such a thing as "known" local winds accurately on the flight path)
You'd tend to try to reconstruct the aircraft flight path and work out the discrepancies.
If I know the aircraft configuration (cruise makes that easy in this case) and have normal acceleration recorded (nominally at 8Hz) and angle of attack recorded (at maybe 2 Hz, I cant recall what the reg calls for) then as OEm I can workout what the speed must have been, since only one speed will give that 'g' for that AoA. Do that for every data point on a reconstructed flight path, and you'll have a reconstructed airspeed you can now compare to the recorded ones. Hopefully they start in agreement somewhere (or all have a common offset, so you can correct any errors in the config data, such as weight). You then move foreward and look for the divergences from the constructed data, and try to build a hypothesis for why its going on.