We are watching a multi-day snow squall event around Lake Nipigon beginning in the early hours on Sunday lasting as long as Tuesday afternoon.
A low-pressure system expected to bring a scattered 1-4cm across Northern Ontario will move through the region. Following a trailing cold front, north and northwest gusting between 25 and 50km/h will develop and last throughout Sunday extending into Tuesday.
As the system begins to pull away, local lake enhancement for areas south of the lake is expected. This would include portions of Oskawe Lake, Elizabeth Lake and Jessie Lake. Local snowfall totals between 3-7cm are likely.
Weak to moderate, and at times intense, snow squalls will develop with peak snowfall rates between 1 and 5cm per hour. These snow squalls will develop in a northwest direction impacting areas southeast of the lake.
There is some question as to whether or not the winds will be mainly north or mainly northwest. Depending on the direction, the areas of the heaviest snowfall may shift to the left or right. For this forecast, we have gone on the side of primarily northwest winds although, if the primary wind direction is from the north, all the highlighted areas will shift 5-25 kilometres to the west depending on the exact location on the map.
Please review our per-scale discussion below for our current discussion.
Areas in red and marked with a '5' can expect snowfall totals between 20 and 40cm. This includes Fairloch Lake and Postagoni Lake, including portions of Highway 11. In this region, snow squalls are likely to remain stationary for the longest duration of time. This will create snowfall totals near 40cm for some localized areas with the potential to overachieve and produce totals between 40 and 45cm.
Areas in the orange and marked with a '4' can expect snowfall totals between 15 and 30cm. This extends from the shores of Lake Nipigon southeast towards Lake Hean and Kilgour Lake. The majority of this region will see totals between 15 and 25cm although areas near the red region (or area marked with a 5) could see those totals push towards 30cm. The best risk is closer to the lake as the squalls will lose some of their energy further inland.
Areas in the yellow and marked with a '3' can expect snowfall totals between 10 and 20cm. This region includes Pine Portage and Oskawe where local lake-enhancement from the system snow could produce as much as 5-10cm. As the snow squalls shift in a north and northwest wind, isolated squall bands may briefly pass over these locations and produce another 5-10cm of snow, locally 15cm. Snowfall totals around 15cm are likely with locally higher amounts towards 20cm and isolated locations reaching towards 25cm. Further inland towards the southeast such as Barbara Lake and Kabamichigama Lake can expect snowfall totals between 10 and 15cm of snow. If the snow squalls can remain stationary for a long period of time, locally higher amounts towards 20cm are possible this far inland. Towards the east, including the Beardmore region, snow squalls may briefly clip this region as they shift left and right with the north and northwest winds. Snowfall totals between 10 and 15cm are likely.
Areas in the green and marked with a '2' can expect snowfall totals between 5 and 15cm of snow. This includes much of Lake Nipigon including Oribine Lake and Poplar Lodge. Beardmore is also considered on the edge of this region. The majority of these locations can expect snowfall totals around 10cm with local totals closer to 15cm towards the yellow highlighted regions and towards 5cm the further away you reach. Inland towards Elizabeth Lake, Jessie Lake and Cameron Falls. Snowfall totals between 5 and 10cm are likely with lake-enhancement from the system snow. Isolated snow squalls may produce final totals near 15cm in this region. Just north of Highway 17, snowfall totals between 8 and 13cm are likely. This includes Gurney Lake and Blair Lake.
Areas in the blue and marked with a '1' can expect snowfall totals under 5cm with the majority of the highlighted places seeing less than 2cm. Areas near Lake Nipigon and the squall bands could see local amounts towards 5cm. Over Highway 17 including Lloyd Lake and Vert Island, snowfall totals could locally overachieve to near 10cm as isolated squall bands may reach just far enough inland to affect portions of Highway 17.
Hazardous conditions are expected along much of Highway 11 from Beardmore to Nipigon and hazardous conditions are 'possible' on Highway 11 between Nipigon and Pays Plat. Isolated road closures are possible.
We will continue to monitor this event and will update as needed.