Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 311 AM EST Wed Jan 04 2017 Valid 12Z Wed Jan 04 2017 - 12Z Fri Jan 06 2017 ...Very heavy snow possible over the Sierras... ...Heavy snow possible over parts of the Great Basin and Central/Southern Rockies... ...Heavy lake effect snow downwind from Lake Ontario ...Heavy rain possible over the Central California Coast... An upper-level low over the Pacific Northwest will slowly weaken and move to parts of the Great Basin by Thursday evening. Onshore wind will drive a plume of moisture into Central/Southern California also through Thursday. The system will produce rain and snow from California/Oregon eastward to the Northern/Central Rockies that will end over the Northern Rockies/Oregon by Thursday morning. The rain and snow will end over parts of Northern California by Thursday evening while rain and snow will move into parts of the Southwest and Southern Rockies. In addition, the rain will be heavy at times over the Central California Coast. Likewise, the snow will be very heavy over the Sierras. Meanwhile, upper-level energy over Central Canada will move southeastward to the Middle Mississippi Valley by Thursday evening. The energy will trigger snow over parts of the Central Plains on Wednesday that will expand into the Middle Mississippi Valley/Ohio Valley on Thursday. Additionally, upper-level energy over the Upper Great Lakes will move into Southeastern Canada by Thursday. The system will produce rain and snow over parts of the Ohio Valley and Central/Northern Appalachian as well as parts of New England that will end over the Central Appalachians by Wednesday evening. In the meantime, cold air will move over the Great Lakes producing lake effect snow downwind from the lakes. The low-level flow will aid in producing heavy snow downwind from Lake Ontario. Elsewhere, developing low pressure along the Southeast Coast will aid in producing rain over parts of the Southeast Coast by Thursday evening. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php