Hi Ed - 
 
I had a similar issue here with ventRate... I think to fix this I had
  to add this line:
 
varDict["Additional Fire Weather Parms to Possibly Populate in
  Step 2"] = ["MixHgt","TransWind"]
 
There are some good comments in the ForecastBuilderNationalConfig
  file that I found helpful. 
 
Kirby~