Skookum Flats - White River is 100% rideable right now.  There is a little snow here and there but all compressed enough that riding it is easy.  You will have to step over a few downed logs.

Few things:  White River Trail is a LOT more sunny than Skookum -- that equals warmer/drier etc.

Skookum is pretty humbling due to slippery roots. A lot of this trail sees NO sun this time of year.  For this trail I keep my eyes on the Huckleberry Creek Snotel.  This is data station is just up the road from the bottom of Skookum.  It seems pretty true to actual snow levels for this trail. 

http://www.wcc.nrcs.usda.gov/nwcc/site?sitenum=928&state=wa

And don't be fooled by the parking lots -- they hold the most snow you will see all day.nyway, all will change as soon as the snow level goes down - go get it while you can -- Skookum in January!