Upwards of 90 mm of rain forecast on Coquihalla Highway (VIDEO)

Heavy rain is falling on the high-elevation mountain passes Sunday, and it's expected to continue through to Monday.

In an updated weather alert Sunday morning, Nov. 14, Environment Canada says upwards of 90 millimetres of rain is expected to fall on the Coquihalla Highway between Sunday morning and Monday afternoon.

“An atmospheric river event will bring heavy rain to the region beginning this morning,” Environment Canada says.

“There is also a chance of seeing wet snow near Coquihalla Summit late this afternoon and early this evening as snow levels temporarily lower from 2200 metres to 1400 metres.”

Rain and some wet snow at Pennask Summit is also forecast on the Okanagan Connector to Kelowna, along with strong gusting winds. Up to five cm of snow could fall at the summit overnight.

The weather service warns that wet snow and heavy rain will cause “challenging driving conditions due to water pooling on the roads and reduced visibility.”

“Heavy downpours are likely to cause flash floods and water pooling on roads,” Environment Canada says. “Localized flooding in low-lying areas is possible. Be prepared for winter conditions at higher elevations.”

To the east, heavy snow will continue to fall on the Rogers Pass area, before changing to heavy rain later this afternoon. Rain is expected to persist through Monday afternoon.