PSA Silver Basin is part of Crystal Ski Area

A good lawyer would try to establish gross negligence and then those disclaimers would be more or less worthless. ...

Yes that is what would be required. 

Gross Negligence
An indifference to, and a blatant violation of, a legal duty with respect to the rights of others.

Gross negligence is a conscious and voluntary disregard of the need to use reasonable care, which is likely to cause foreseeable grave injury or harm to persons, property, or both. It is conduct that is extreme when compared with ordinary Negligence, which is a mere failure to exercise reasonable care. Ordinary negligence and gross negligence differ in degree of inattention, while both differ from willful and wanton conduct, which is conduct that is reasonably considered to cause injury. This distinction is important, since contributory negligence—a lack of care by the plaintiff that combines with the defendant's conduct to cause the plaintiff's injury and completely bar his or her action—is not a defense to willful and wanton conduct but is a defense to gross negligence. In addition, a finding of willful and wanton misconduct usually supports a recovery of Punitive Damages, whereas gross negligence does not.

Given all the warning signs and the care that the ski patrol takes in their operations -- establishing gross negligence would be hard to do.

Not that this would stop a "Lionel Hutz" from filing suit, but I believe the ski area gets sued on a regular basis because of more run of the mill injuries and has attorney's on retainer to deal with these sorts of things all as part of the cost of doing business.

For example about 25 years ago I was skiing at Mt Baker ski area over Thanksgiving, fell and dislocated my shoulder.   I went to the DR and had an MRI -- I didn't need surgery, but some months of physical therapy.    My health insurance provider paid for all of this -- however an adjuster called me and asked a series of questions about where the injury occurred and the health insurance companies lawyers did contact the ski area and received a response from their legal department.   It didn't go any further than that -- but the ski area did need to have an attorney respond.

I saw the following in the crystal uphill policy

3) When the ski area is open for the season, all uphill travel into Southback is prohibited.

I was there 2 weeks ago and checked in with the ski patrol. I told them we were headed to silver basin. Is this "No Southback" policy new? Is it a result of this recent incident? Or maybe they were okay with it since chair 6 was closed? Or maybe it is just the laissez-faire attitude that has enabled my touring in silver basin for the past 25 years?

The Southback prohibition is definitely a major change. As is much of the current Uphill Travel Policy, since most items in the 8-item main list have changed completely!

Thanks to the wonder which is the Internet Archive Wayback Machine, we can easily check the previous policy:
web.archive.org/web/*/https://crystalmou...afety/uphill-travel/

The most recent previous saved version as of June 9, 2016:

Uphill Travel Policy

Hiking, Skinning & Snowshoeing within the Ski Area Boundary

1. Uphill travel within “closed” terrain is not permitted; Avalanche control work—including explosives use—may occur at any time.
2. Closures are posted only at the TOP of trails; those entering from below shall be considered to be trespassers. Uphill travelers may check in with Ski Patrol for current closures, recognizing that status may change at any time.
3. Traveling above “No Hiking Above This Point” signs is prohibited. These signs indicate sufficient avalanche hazard exists to warrant closure to all, regardless of whether one hiked up from the bottom, or whether one has or hasn’t used a lift ticket.
4. The absence of the “No Hiking Above This Point” signage at the top of operating lifts indicates that uphill travel is permitted in ‘open’ terrain.
5. Anyone boarding or attempting to board a lift without a valid lift ticket or pass shall be considered a trespasser.
6. Uphill traffic must keep to the side of ski trails and well out of the way of downhill skier traffic.
7. Pierce County leash laws apply in the developed ski area; unrestrained dogs’ handlers will be considered trespassers.
8. The designated runs for uphill travel are Quicksilver, Queens Run, Lucky Shot and Kelly’s Gap Road.

After Hours Uphill Travel Policy

1. DANGER! No uphill travel when light is flashing. Several lights are located in the base area.
2. Uphill travel allowed on Quicksilver, Queens Run, Lucky Shot and Kelly’s Gap Road only*
3. Use extreme caution for unmarked hazards and heavy equipment including but not limited to snowmobiles, snowmaking, winch cats and cables.
4. For more information you can contact Ski Patrol during operating hours: 360-663-3061
*Quicksilver trail is the only area within the ski area boundary that uphill travel is allowed at all times.

See Backcountry Safety for more information about your responsibilities when accessing terrain other than by lifts.

Crystal Mountain accepts no liability or responsibility for accidents that occur or as a result of uphill travel. RCW 4.24.210

And compared to the current online version at crystalmountainresort.com/safety/uphill-travel/ as of December 10, 2016, with recent changes marked in red:

Uphill Travel Policy

1. DANGER! No uphill travel when light is flashing. Several lights are located in the base area.
2. When the lights are not flashing, all uphill travelers within the ski area boundary must check in with patrol. No exceptions. 360-663-3061.
3. When the ski area is open for the season, all uphill travel into Southback is prohibited.
4. Uphill travel within “closed” terrain is not permitted. This includes areas marked with “No Hiking Above This Point” signs. Avalanche control work—including explosives use—may occur at any time.
5. Uphill traffic must keep to the side of ski trails and well out of the way of downhill skier traffic.
6. When traveling uphill after hours, use extreme caution with unmarked hazards and heavy equipment including but not limited to snowmobiles, snowmaking, winch cats and cables.
7. For more information contact Ski Patrol during operating hours: 360-663-3061.
8. Anyone found in violation of these rules will be subject to a fine and possible prosecution under Washington State Law RCW 79A.45.070


After Hours Uphill Travel Policy

1. DANGER! No uphill travel when light is flashing. Several lights are located in the base area.
2. Uphill travel allowed on Quicksilver, Queens Run, Lucky Shot and Kelly’s Gap Road only*
3. Use extreme caution for unmarked hazards and heavy equipment including but not limited to snowmobiles, snowmaking, winch cats and cables.
4. For more information you can contact Ski Patrol during operating hours: 360-663-3061
*Quicksilver trail is the only area within the ski area boundary that uphill travel is allowed at all times.

See Backcountry Safety for more information about your responsibilities when accessing terrain other than by lifts.

Crystal Mountain accepts no liability or responsibility for accidents that occur or as a result of uphill travel. RCW 4.24.210

I saw the following in the crystal uphill policy

3) When the ski area is open for the season, all uphill travel into Southback is prohibited.

I was there 2 weeks ago and checked in with the ski patrol. I told them we were headed to silver basin. Is this "No Southback" policy new? Is it a result of this recent incident? Or maybe they were okay with it since chair 6 was closed? Or maybe it is just the laissez-faire attitude that has enabled my touring in silver basin for the past 25 years?

So what did the Crystal Ski Patrol say about your plans for Silver Basin when you checked in? Did you go to Silver Basin or somewhere else?

So what did the Crystal Ski Patrol say about your plans for Silver Basin when you checked in?  Did you go to Silver Basin or somewhere else?

They said, "have a good time." That was it. No avy beta or anything else. It was quite pleasant.

This is a good call out. I get both sides of the argument but seriously, let patrol do their job. Just as you wouldn't make a wsdot road worker stand with arms full waiting for you to save 1 minute on your commute... right?

What I don't get is bc tourists choosing a destination that's lift served or side country. Why make the effort when you can get after your 'own' piece of fresh backcountry? Every resort around here has nice tour options that avoid this whole topic if you just put your back to the lifts and explore.