The first system in the East is the result of an upper-trough. As this system swings through the Eastern U.S. Tuesday and Wednesday, widespread rain will overspread the Commonwealth tonight into the first half of Wednesday after producing heavy rain in Texas and Louisiana Monday. The heaviest rain for us will likely fall around the Wednesday morning commute. Totals will be around an inch for many places in Central Virginia, with some higher totals possible. Here is the expected output from this upper system in the Eastern U.S. 
The precipitation you see in the Plains and West is a result of the next upper system currently entering the Rockies. This storm system will bring more snow to the Mountain West, and another round of rain for the Plains. Check out the Winter Advisories/Watches/Warnings in Utah, Colorado, Wyoming, Idaho, Montana, and western Nebraska:
You can watch the snow as it falls in Colorado on their live traffic cams here. Also notice the Wind Advisories/Warnings from California to Arizona as this system brings gale-force winds. This potent storm will track northeast the rest of this week, passing through the Great Lakes Friday into Saturday. This is the storm that will sweep a cold front through Virginia Halloween and bring a slight chance for some rain. At this time, it appears any showers that do affect Virginia will exit the area Saturday evening. We'll be providing updates for the Trick-or-Treaters as we get closer to Saturday.
