the met at GRR actually had a great write up on this
Impact of Tropical Storm Rai (west Pacific) on our weather for next week As it turns out, Tropical Storm Rai, in the western Pacific is heading due west toward the Philippine Islands. It should become a typhoon by this evening. Why to we care about this in Michigan? As it turns out, it will have a major impact our weather for the next week. What this does is it stalls the MJO on the edge of phase 6 to phase 7 since in phase 7. In phase 7 the area near the Philippines should be dry. That changes the entire northern hemispheric wave train. It will delay the arrives of the really cold air till after Christmas (we need a solid phase 7 for that cold air to get here). This means largely zonal flow for our area for the next week. That will prevent any strong pushes of cold air and also not allow the much phasing with the next two storm systems that follow the Thursday event. The result will be the system on Saturday will have a northern and southern branch component to it. The northern branch part stays north and the southern branch part stays south. Still we are close enough the jet entrance region driving the system that some light rain/snow is possible. Northern area will see mostly snow, central sections a mix of rain and snow and mostly rain south of I-94 (not enough push of the cold air for snow there). Any precipitation with this will be meager at best. There is another system early next week, that too lacks any real cold air. Expect some light snow north and a mix south. Finally a better system is possible near Christmas. This is about the time that the tropical cyclone in the west Pacific influence should be fading. Maybe snow by Christmas?
Bill Marino, great forecaster, been there forever