In our flight today we climbed out northbound to 20 k feet toward 
Cheyenne.  We had a few problems with the Winds setup that caused us 
to reboot at about 2017.  A solid undercast of st cu was present at 20 
k feet, with occasional higher regions of cloud.  We picked one of 
these regions and descended to below the stratiform layer, where we 
observed that there were regions with lower convective bases caused by 
cumulus clouds that merged with the stratiform region.  The bases of 
the cumulus clouds were about 11.5 k feet, while the bases of the 
stratiform regions was at about 15 k feet.  The air was cold, with 
temperatures at 11.5 just slightly below freezing.  

We selected one of the cumulus regions with a particularly hard looking 
base and sampled it at 11 kfeet just below the cloud base, then at 11 
kfeet climbing to 12 through the base (Jensen maneuver) at 2046, 
followed by a pass at 12, and higher until the cloud dissipated about 
the time our stairstep up reached the stratiform layer.  There were 
some ice particles in the cloud we sampled, but it was not a significant 
producer of precipitation below the base of the cloud. 

We then moved eastward to try and find a more isolated, precipitation 
free cloud, which we did and made a pass below the base and a couple in 
the cloud stepping up.  We also tried another zoom up through the 
base, but the cloud was in its dissipating stages by this time and 
pretty much fell apart.  

We then did some pitch maneuvers (at 2104), followed by a descent to 
approximately 2500 feet AGL for the return to JeffCo as a boundary layer 
leg.  We have some photos of each cloud that was sampled today.

Jeff Stith