The September 21–23, 1999 rain event in the Maritime Provinces of Canada

On September 21 to 23, 1999 a significant rainstorm giving up to 300 mm of rainfall affected the Maritime Provinces of Canada. Rainfall amounts over the 2 to 3 day period exceeded the 1 in 100 year return period rainfall in parts of Nova Scotia, New Brunswick and Prince Edward Island. The extreme rainfall resulted from the interaction of the remnants of tropical storm Harvey and an extratropical cold front. Numerical weather prediction models did not handle the system well. Experiments with a 10, 24 and 100 km resolution model and different convective schemes provide insight into the ability of NWP to forecast these events. This presentation provides a detailed compilation of the data for the overall storm event, an interpretation of the expected frequency of the event, details of the rate of rainfall at selected locations as well as the results of numerical simulations of the precipitation field.