The Ocean Forecasts for the Estuary and Gulf of St. Lawrence are issued by the Modelling and Operational Oceanography section of the Canadian Hydrographic Service (CHS), Maurice Lamontagne Institute (MLI), Fisheries and Oceans Canada (DFO).
The surface current and sea ice forecasts for the Gulf of St. Lawrence are extracted from a three-dimensional numerical model computing the oceanic circulation under the influence of tides, the St. Lawrence River fresh water runoff, the atmospheric forcing, and the sea ice drift, growth and melt. 
The model has been validated under a series of scientific and operational research and development programs within the Department of Fisheries and Oceans Canada. The validation process was done against a number of oceanographic observations including currents, water levels, water temperature and salinity, and sea ice drift, concentration, and thickness.
The physical data used as input to the model are:
- Tidal elevation at Cabot and Belle-Isle Straits;
- Forecasts of fresh water run-off at Quebec City;
- Meteorological forecasts issued from the GEM model of the Canadian Meteorological Centre, Meteorological Service of Canada, which includes wind, air temperature, cloud cover, and relative humidity;
- Ice observation integrated in daily charts from the Canadian Ice Service, Environment Canada.
Important Notices - Surface Currents
Estuary (from Quebec City to Cap de Bon-Désir)
The surface current forecasts of the St. Lawrence Estuary are extracted from a three-dimensional numerical model that synthesizes the oceanic circulation under the influence of the tides and of fresh water runoff from the St. Lawrence River, but without wind forcing. The model results were validated against a statistically significant series of drifting buoy tracks in calm weather conditions. The tides are responsible for a high percentage of the current energy in this region, but the forecasts must be used with caution in intense or extreme wind conditions.
Gulf of St. Lawrence
The surface currents forecasts for the Gulf of St. Lawrence are extracted from a three-dimensional numerical model computing the oceanic circulation under the influence of tides, the St. Lawrence River fresh water runoff, and the atmospheric forcing. The model has been validated under a series of scientific and operational research and development programs within the Department of Fisheries and Oceans Canada. The validation process was done against a number of oceanographic observations including currents, water level, water temperature and salinity.
Saucier, F. J., and J. Chassé. 2000. Tidal circulation and buoyancy effects in the St. Lawrence Estuary, Canada, Atmosphere-Ocean, 38(4), pp. 1-52.
Saucier, F. J., J. Chassé, M. Couture, R. Dorais, A. D'Astous, D. Lefaivre, & A. Gosselin, The making of a surface current atlas of the St. Lawrence Estuary, Canada, Fourth international conference on computer modelling of seas and coastal regions (C. A. Brebbia & P. Anagnostopoulos, Eds.), J. Computational Mechanics, Wessex Institute of Technology Press, 87-97, 1999.
The St. Lawrence Global Observatory team maintains and operates the OGSL portal including the Ocean Forecasts Web site during regular business hours. The OGSL has put in place a monitoring system in order to be notified of any Internet service interruption and has established procedures to ensure that the necessary actions are taken no later than the next business day.
Databases accessible via the OGSL portal are under the responsibility of data producers who ensure their maintenance and take the necessary actions should any service interruption occur.
Seasonal Services
Certain products and services are only available during specified periods. In these cases, the availability periods are clearly indicated on the site.
e. g.: Sea Ice Forecast.
