[gradsusr] GFS Winds

[MARK SPONSLER]

Hi all,
This is not a direct Grads questions but more of a GFS 0.25 deg model question.

I'm using Grads to try and plot upper level winds.

Its a basic 4d plot for 1 time, a single lat and lon, and then all levels between 1000 and 550 mbs using ugrdprs and vgrdprs

The weird thing is the wind speeds vary wildly from level to level with the data on the X25 and X75 mb levels (i.e. 725, 775, 825, 875) levels seeming more valid than the X00 and X50 mb levels (i,e, 700, 750, 800, 850). 

See attached image.

Should I only be plotting on the X25 and X75 levels?
Or is something else going on? Or is my perception of how the upper level atmosphere should work not consistent with reality?

I have 2 files I've downloaded using Dods, one in March 2019 and the other a few days ago,  and both display the same behavior.

Any suggestions appreciated.

Thanks,
Mark
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