Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 408 PM EST Mon Jan 18 2016 Valid 00Z Tue Jan 19 2016 - 00Z Thu Jan 21 2016 ...Temperatures will remain well below-normal across the Ohio Valley and Mid-Atlantic region... ...Snow showers will continue to set up downwind of the Great Lakes... ...Heavy rain and mountain snow are expected for the Pacific Northwest and northern California... An Arctic airmass sprawled across much of the eastern half of the Nation will keep temperatures well below-normal from the Ohio Valley to the Mid-Atlantic region on Tuesday...with temperatures slightly rebounding on Wednesday. The surge of arctic air over relatively warm lake waters should allow snow showers to continue to set up downwind of the Great Lakes into Tuesday...but activity should decrease by Wednesday as high pressure slides eastward and winds diminish across the region. Out west...a series of Pacific systems moving inland will bring rounds of heavy rain and mountain snow to portions of the Pacific Northwest and northern California Tuesday and Wednesday. These systems should weaken while progressing downstream...but could still trigger widespread light to moderate snow over the Intermountain West and Rockies. Snow will be possible with weak shortwave energy while it ejects out of the Rockies early Tuesday and crosses the Middle Mississippi and Tennessee Valley on Wednesday...with the best chance for any accumulations expected in a swath stretching from eastern Nebraska into Kentucky. Gerhardt Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php