Weather models are fundamentally different from climate prediction models. Weather models are based on fluid dynamics. Climate models are based on general circulation, which is not the same as fluid dynamics. They do different things, and the results of one don't feed into the other. I say that as a non-modeler quoting what I've read about models, but when it's said, it's consistently said.
Sorry to drop off the thread for spring break activities the next two days, but I'll be back Thursday if you want to reply.
Actually they do. The GCM models often use local results from weather models to add parameters for clouds, typically turned into percentages of types of clouds. These estimates are the only way to get semi-realistic estimates of clouds and the effect of clouds. What is lacking unfortunately, is a feedback from the GCM models and their extra water vapor back to the weather models to see what effect the extra water vapor has on weather.