This entire article is a very worthwhile read.

the shortage will continue to force the price of silver higher until enough actual silver makes its way into the eligible vaults at the COMEX, or until another means of price discovery is found (such as a competing exchange). As much as the margin increases can damage investor psychology and confidence, they do not in any way alter the fundamental foundation. As long as the COMEX takes the full delivery month to conjure and cajole as little as 870,000 ounces for delivery, the fundamental shortage is unchanged. The key will be SIFO. Unless and until there is a full normalization of forward rates, not just a roller coaster around zero, the shortage is on. The rest is just volatile, oft-times painful, noise.

via Precious Metals: Comex Silver Will Make It Through May, But Barely | Markets | Minyanville.com