A warm front accompanied by heavy rainfall is forecast to move into the Grand River watershed on Monday and persist through Wednesday. Temperatures are forecast to reach upwards of 13 degrees and are not expected to decrease overnight during this event.
Rainfall totals of 40-50 mm are expected across the watershed beginning Monday morning and through Tuesday, with an additional 5-10 mm falling on Wednesday. The combination of warm temperatures and rainfall is expected to trigger significant runoff into the river system.
These conditions are expected to result in a total melt of the remaining snowpack and very high flows in rivers and streams across the watershed. This will result in flows similar to those experienced during normal spring flooding.
Ice jams currently in place in the Grand River through the City of Kitchener (Freeport), the City of Cambridge, City of Brantford and community of Cayuga have a high potential of causing additional flooding.
Ice jams can form and release without warning and extreme caution should be used in areas where they are occurring.
All GRCA reservoirs are at low winter holding levels and have storage available to manage runoff from this event which will help reduce downstream flooding.
Town of Cayuga: Haldimand County flood coordinators are asked to warn residents in the floodplain in the Town of Cayuga in anticipation of ice jam flooding as a result of this event. Flows are expected to peak through Cayuga overnight Wednesday.
Town of Dunnville/Port Maitland: Haldimand County flood coordinators are asked to contact the Canadian Coast Guard to dispatch an icebreaker to the mouth of the Grand River in Port Maitland to reduce the potential for ice jams at this location. Flood coordinators should also warn residents in the floodplain. Flows are expected to peak on Thursday.