First, the description, then a picture which will help this all make sense.
The posts for the railing are built in a sideways "H" configuration when viewed from the top. The railings slip into the "H" and are secured with nails though the face of the posts. The posts are then capped with a square cut from a 2x8 and nailed onto the top.
I removed the nails that secured a railing section into the posts, as well as the nails from one side of 2 caps. This allows me to raise the section of railing enough to shovel underneath it. The railings fit fairly tightly between the posts, so I can't raise either end to their final height in a single lift. To solve this, I built "stepped" supports, allowing me to raise the railing incrementally until it is at its final height.
Although this section of railing is now a bit shaky, I haven't made the deck any less safe since the railing section can't go anywhere except up. In the spring, I'll secure the section with a few screws just to tighten it up until next winter.
I've used the system twice this year and I'm quite happy with the results.