Loading the best weather snapshot

First off, I am using ASE sp4 with FS9. I also use REX for environment and cloud textures. Over time I will create a new set of textures in REX for clear skies, IMC, partly cloudy, etc and save these texture grouping as a snapshot in ASE. I have about 5 texture sets saved so far. When planning a flight, I upload my flight plan into ASE, and then press the "process" button. I am then asked if I want ASE to loaf the appropriate snapshot textures for the weather condition. It seems that no matter what the weather conditions are, ASE will always load Partly Cloudy 1 or Partly Cloudy 2 snapshots even if weather is overcast and raining. I have 2 sets of textures for bad weather and those are never selected by ASE. How does ASE choose an appropriate snapshot for airline flights? How can I get ASE to select texture sets other than Partly Cloudy?

Todd