It's time to start a pool for those interested in guessing when key roads in Glacier, Rocky Mountain, and Yellowstone national parks will be open for summer traffic.

Plowing crews are hard at work in each of those three parks, but as the accompanying photos from this week clearly show, the going ain't easy. At Glacier, word has it that this winter's snowfall was 150 percent of normal. And it's still coming down.

Wondering when the 50-mile-long Going-to-the-Sun Road might be open, end-to-end, this summer? No one's saying. Here's what park officials have posted on their website, in red no less:

Plowing the Going-to-the-Sun Road is a monumental challenge each year. Unpredictable spring snow storms or other weather related eventgs can slow down plowing progress. It is not uncommon for plowing crews to need to re-plow sections of park roads when weather events happen. Safety for our plowing crews, contractors, and the public is our utmost concern and priority. These unknown factors make predicting the opening of the Going-to-the-Sun Road impossible. 

Last year the road was completely open by June 24. In 2008, that didn't happen until July 2. The latest opening on record is July 10, 1943, when the snow was allowed to melt out. The earliest Logan Pass was ready to handle motorized traffic was May 16, 1987.

At Rocky Mountain, plow crews began attacking Trail Ridge Road on April 19 from both ends of the road. What they found on the eastern side were 10-14 feet of snow between Many Parks Curve and Rainbow Curve. As park spokeswoman Kyle Patterson put it in a release, that's "the most seen in this area for years."

While recent snow storms have been challenging to the plow drivers, they've also made some superb spring conditions for snowshoers and backcountry skiers, according to the park. That said, if you have one of those activities in mind, check with rangers for the latest avalanche conditions.

Currently, Rocky Mountain officials are predicting that the Trail Ridge Road will be open May 27, in time for Memorial Day Weekend, "weather permitting." To check on the status of the plowing operations, you can call 970-586-1222.

In Yellowstone, aggressive efforts by plowing crews had park officials saying Friday that the road from the East Entrance over Sylvan Pass to the Fishing Bridge area just north of Lake should be open in six days, or in time for next weekend.