Winter weather warnings are in effect in parts of British Columbia as Environment Canada is forecasting heavy rain and snow at higher elevations in the province. The agency upgraded its weather advisories for the Metro Vancouver area on Thursday morning, issuing rainfall warnings for the North Shore, Tri-Cities and western Fraser Valley regions. The weather office says a low-pressure system will move into the south coast, bringing light showers that will become heavier through the day and into the weekend. Total rainfall accumulation could reach 50 millimetres in areas, with potential for flash flooding. “With freezing levels dropping along the south coast, particularly during the heaviest rainfall overnight, higher elevations near the mountains may see up to four centimetres of snow,” Environment Canada said. “With some ground frozen or near freezing, runoff may cause localized flooding and water pooling on roads.” The Sea-to-Sky Highway between Squamish and Whistler will see upwards of 20 centimetres of snow Thursday morning through Friday evening before tapering off around midnight, creating hazardous driving conditions, the weather warning said. The rest of the south coast region, including Vancouver Island, is expected to remain under a special weather statement into next week, as Environment Canada says steady rainfall beginning Thursday afternoon could turn to wet snow at higher elevations. Temperatures across the region are expected to warm up Friday before dropping to below zero again early next week when an Arctic ridge of high pressure is forecast to settle over the region, bringing “very cold and dry air,” the weather office said. Farther north, a snowfall warning has been issued for areas east of Prince George and Williams Lake, with a long period of snowfall expected to dump between 10 and 20 centimetres and reducing visibility for travellers along Highway 16.