If you're looking for snow before 6pm you're going to be disappointed, the main front won't get here until the evening, with the heaviest at around 9pm.
http://www.wetterzentrale.de/topkarten/fsavneur.html
One chart that I find very useful for when the most intense precipitation will come is the 700hpa vertikalbrew chart on the GFS. This shows the negative vorticity advection (yellow through to purple) to be at it's strongest over Yorkshire somewhere between 6pm and 12pm.