BOAC,
Imagery from 02h07. Position (square box) is the 02h10 ACARS position.
(Source Annexe 1 of the French version of the first BEA interim report.)
Temperatures above -50C
Temperatures above -75C
Would appear to be rather close to a Cb.
From Tim Vasquez's June 1 2011 re-analysis, his worst case scenario, and general conclusions.
[p]arcel was constructed that just barely achieves the isolated -80 deg C overshoot temperature detected on METEOSAT imagery. This was readily accomplished with a surface temperature of 27 deg C and dewpoint of 23 deg C (thus it realistically accounts for a certain amount of boundary layer mixing). The CAPE value obtained is 1067 J/kg, which by textbook definition is considered marginal for severe weather and typical for the tropics. That is not to say it does not have severe weather risks, as the formula for typical maximum observed updraft velocity is: w=0.5*((2*CAPE)^0.5) which in this case gives 23 m/s (51 mph). It is probable that even this amount of instability was not observed, due to the potential for extensive mixing with an average dewpoint of 18C in the lowest 150 mb.
Furthermore, researcher Ed Zipser and others in their studies of oceanic equatorial cumulonimbus clouds emphasize the dilution of updraft strength in the clouds they sampled, though this mainly occurs below about FL200. This mid-level weakness probably contributes in some way to the lack of charge separation and electrification (i.e. lightning). Above that level, ice-filled updrafts are warmed by latent heat of sublimation, restrengthening the updraft relative to the surrounding environment and this allows the updraft to regain momentum and the cumulonimbus cloud to reach the stratosphere. Zipser states that updrafts are usually strongest in the upper troposphere compared to lower levels and updraft velocities of 20 to 40 kt do occur occasionally. The role of a strong updraft or turbulence within the storm cannot be completely ruled out, especially since METEOSAT measurement shows that cumulonimbus overshoots reached at least 6,000 ft above the tropopause.
....
(Conclusions)
Air France Flight 447 crossed through an area of tropical showers and/or weak thunderstorms with weak to moderate updrafts and a high likelihood of turbulence. The flight penetrated one cell at about 0150 UTC and then entered a cluster of cells beginning at 0158 UTC. The suspected zone of strongest cells was reached at 0208 UTC, which corresponds with the beginning of a track deviation, and another cell appeared to be reached at 0210 UTC, which corresponded with the time of autopilot disconnect.
.....
Tropical storm complexes identical to or stronger than this one have probably been crossed hundreds or thousands of times over the years by other flights without serious incident, including ascents and descents through critical icing zones in tropical showers.
Air France 447 - AFR447 - A detailed meteorological analysis - Satellite and weather data