Add diagnostic output that keeps track of vertical motions (and other thermodynamic variables) in updrafts and downdrafts

[crterai]

It would be great if we had a way of diagnosing mass flux (keep track of only positive values of omega or vertical velocity, the same for downward, and then the fraction of time it is positive or negative)- so we can better diagnose vertical mixing from resolved circulations without having to save instantaneous snapshots of vertical motion to calculate this.
https://glossary.ametsoc.org/wiki/Convective_mass_flux

Similarly, if we can keep track of vertical transport of moisture, potential temperature, and other variables under updraft or downdraft conditions, we can also diagnose vertical mixing of moisture, heat, etc.