An Experiment in Subjective Probabilistic Quantitative Precipitation Forecasting: Forecasts and Verification during the Elbow 2001 Field Study

The Effects of Lake Breezes on Weather (ELBOW) 2001 was a field experiment conducted from May 1 to August 31, 2001 in southwestern Ontario. The project was a collaborative effort of the Meteorological Service of Canada, York University, University of Western Ontario and University of Guelph Ridgetown College. Other contributing agencies were The Weather Network and the US National Weather Service. The primary objectives of the experiment were to learn more about how lake breeze fronts interact with themselves and synoptic-scale weather features to initiate and enhance convective storms, and to evaluate and improve current short-range forecasting of the occurrence and behavior of lake breeze fronts. The ELBOW 1997 field study (King and Sills, 1998) and other works (Murphy, 1991; Clodman and Chisholm, 1994; Sills and King, 1999) identified that many excessive rainfall producing quasistationary Mesoscale Convective Systems (MCS) in southwestern Ontario are largely governed by the development and propagation effects of lake breeze boundaries. Previous research has also demonstrated the value and merit of Probabilistic Quantitative Precipitation Forecasts (PQPF) as guidance for flood forecasting and risk management in small to medium sized watersheds (Krzysztofowicz, 1998). 4.4