Wow, from where did you resurrect this thread?
The nitty-gritty is absolutely missing, not only from an aviation perspective, but also from the vantage point of atmospheric physics. Several large research projects have been undertaken by various interested institutions, and a large amount of data has been collected. However the conclusions appear rather equivocal.
There are some indications when the atmosphere may be susceptible to microburst formation, but the ability to forecast location and timing has not yet been achieved. In geographical areas prone to dry type microbursts a dry adiabatic layer at altitude, or a rising inversion layer, seems to correlate to a probability of microburst formation. In tropical areas, a conducive environment for wet microbursts, the factors that influence their formation are height of the melting layer, lapse rate, mixing ratio in lowest 1000 meters, and mixing ratio at the melting level. One of the most important factors to emerge from the research is the lack of correlation between storm size and microburst intensity.
Most microburst induced accidents have occurred from flying under or through innocuous appearing CU. These storms were in a building stage and some became very large, however when the accident aircraft penetrated their boundaries they appeared quite benign. Large and threatening storms do not hold the same statistical significance probably because we avoid them more so then the average towering CU. From the post above, listing microburst induced accidents, all were a result of innocuous appearing clouds.
The physical mechanics of the microburst have been well documented with the help of FDR’s, TDWR, rawinsondes, and flight instrumentation (NASA actually flew their B737 through several). Vertical winds in excess of 26 meters/ sec (51 kts) and horizontal shears of 60 – 70 kts are probably fairly common for a good-sized microburst.
How and why microbursts form remains a mystery and contributes to the nitty-gritty lack of knowledge that is prevalent in aviation operations, meteorology, and even in the more academic arena of atmospheric physics.