Jerky changes in view velocity when updating with timer

[rroemmich29]

When I log the velocities inside the update function, I get the following (as sample data):

500
467
220
54
612
497
398
418
700
585
776
825
346
297
552
388
817
542
811

You'll notice that none of the velocities become negative, so I am still struggling to understand why the jitter occurs. Certainly the velocity magnitude should change, but I'm not sure why it momentarily changes direction.