, a BAe 31 Jetstream, was inbound to Prince Albert (YPA), established on V303 at 15,000 feet, about 60 miles north of YPA. The sector Controller advised the crew of ASK 501 of an unidentified VFR target about 9 miles west of them at an unverified altitude of 12,500 feet and climbing. The two a/c passed with 5 miles lateral spacing before ASK 501 pulled ahead due to the speed differenetial. Contact was eventually made with the pilot of the unidentified a/c, CF-RNU, a Mooney 20C, with the assistance of Prince Albert FSS. The pilot explained that he had encountered weather which had forced him to climb and alter course. ACC provided the pilot with weather and flight information and the pilot later informed ATC that he could see the ground and was descending to land at Birch Hills. The ACC Shift Manager spoke with the pilot and explained the potential safety hazard that had developed and ensured that the pilot understood the nature of the problem. Separation was not compromised but safety was not assured for a brief period. OPI - Enforcement Update:Change of OPI: from System Safety to Enforcement.