Signing up for a December race in Portland means taking a gamble with wilder odds than anything in Vegas. In my years running the Holiday Half, I’ve experienced downpours, frost, a smokey closure, perfect brisk sunshine, and wet snowflakes covering my cap. And I’ve also experienced the most well-earned gingerbread cookies ever. The Holiday Half includes multiple distance options, including half marathon, 10-miler, 10K, and 5K options. All participants start the out-and-back course at Daimler…