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An Air France Airbus A340 experienced an accident while landing at Toronto's Pearson International Airport (station identifier CYYZ) around 20:03 UTC (4:03 PM Eastern time) on 02 August 2005, while the airport was under a "Red Alert" due to strong thunderstorms in the vicinity of the airport. NOAA GOES-12 visible and 10.7 micrometer InfraRed (IR) imagery (above) showed the strong convection that was over the Toronto area that afternoon. Cloud top temperatures with the second round of storms quickly cooled to -61 C at 19:45 UTC -- on the 20:02 UTC IR image, a cold/warm couplet (-60 C/-55 C) was noted in the vicinity of Toronto, with a very subtle "enhanced-v" signature developing shortly afterward (20:15 to 20:45 UTC). The convection over the airport at the time of the accident may have been enhanced by lake breeze boundaries and/or outlflow boundaries from convection earlier in the day (16:20 UTC Terra MODIS true color image | 17:59 UTC Aqua MODIS true color image), although these boundaries were difficult to detect in the available satellite imagery. Surface observations indicated a shift in wind direction along with an increase in wind speed to 24 knots (with gusts to 33 knots) around the time of the accident (meteorogram).
GOES sounder-derived Precipitable Water, Lifted Index, and Convective Available Potential Energy (CAPE) products (below) revealed that a northwest-to-southeast oriented axis of moisture and instability was in place across the Toronto region during the afternoon hours, providing a favorable environment for convective initiation and intensification.
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