Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 355 AM EST Wed Dec 18 2013 Valid 12Z Wed Dec 18 2013 - 12Z Fri Dec 20 2013 ...Weather will become increasingly active over the Western half of the Country as a Pacific front drops through the West and an arctic boundary dips down from Canada... ...Conditions should clear out across the Northeast and northern Mid-Atlantic states on Wednesday... A Pacific front will trigger widespread snow showers while it sinks through the Pacific Northwest and Intermountain West on Wednesday. With the exception of some boosted amounts over the favored terrain...a lack of moisture supply should keep precipitation light; However...once the front reaches the Central Great Basin and Southwest on Thursday...it will be able to tap into some Pacific moisture as the supporting energy aloft amplifies and eventually closes off a vortex just off the California coast. The increase in moisture should lead to accumulating snows over portions of the Central Great Basin and bring some much needed rain into Central and Southern California. Strong winds with an arctic boundary dipping down from Canada will force upslope snows over western Montana on Wednesday...and snows should spread out across much of the Northern and Central High Plains as the front plunges farther southeastward over the northern tier Wednesday night into Thursday. Limited moisture across the region should hinder any significant accumulations...but as the boundary sinks into the Middle Mississippi Valley and warm Gulf moisture works it way northward...some freezing rain will be possible late in the period. The coastal low that clipped New England with heavy snows will race towards the Canadian Maritimes on Wednesday. Some light lake effect showers will be possible throughout the forecast period...but elsewhere...the Northeast and northern Mid-Atlantic states should see a break from the recent rounds of winter weather that impacted the region. Gerhardt Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php