Sometimes when trying to debug or better understand a verb it is useful to see the values of its local names or other intermediate results. A quick way of doing this is to add a line to the verb definition that does a global definition.
Open the cf.ijs file and add a line to centigrade to define global gt1 as t1.
centigrade =: 3 : 0 NB. =:
t1 =. y - 32
gt1 =: t1 NB. temp line for debugging info
t2 =. t1 * 5
t3 =. t2 % 9
Run the script and in the ijx window:
After centigrade finished execution you can't see what value the local t1 had, but you can see a copy of the value in gt1.
Remove the line from the script and run the script to redefine centigrade without the debug line.