Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 244 PM EST Tue Jan 10 2017 Valid 00Z Wed Jan 11 2017 - 00Z Fri Jan 13 2017 ...Periods of heavy rain and snow expected to continue for much of the West through midweek... ...Low pressure system expected to bring rain and snow from the Midwest to the Northeast... ...Warming temperatures expected for much of the central and eastern U.S... Periods of rain and snow, possibility heavy at times, will continue to impact the western states as a series of Pacific storm systems move through. Onshore flow will continue to spread warm, moist air from the coast inland to the Interior West. Much of California and Pacific Northwest Coastal areas will have widespread precipitation, with thunderstorms possible. Much of this region is water-logged from the previous days rainfall and additional rainfall could easily lead to flash flooding. Much of the California coast and the Sierras could see excessive rainfall through Wednesday morning. Snow levels will rise as the system approaches, with snow changing to rain or a mix of rain and snow across portions of the Sierras and the Great Basin. Meanwhile snow, potentially heavy for some areas, will persist from the interior Pacific Northwest to the northern and central Rockies. Areal coverage of the rain and snow will decrease by late Wednesday as the system weakens and tracks further inland. Another rain of precipitation is expected across the West Coast as another weak system approaches. A deepening system lifting north and east through Upper Midwest/Great Lakes/Ontario today is spreading rain and snow across the Great Lakes region- with rain from the lower Great Lakes, Ohio/Tennessee valleys and Lower Mississippi valley along and ahead of the trailing cold front. As warmer air lifts into the Northeast late tonight and Wednesday, precipitation will transition to freezing rain or rain. A secondary cold front will bring another round of rain to much of the Ohio valley and southern Great Lakes, with snow and areas of freezing rain for the Upper Midwest as well. A warming trend is expected over the next few days for much of the central and eastern states; numerous locations will have afternoon highs 10+ degrees warmer than average. An arctic surge is forecast for the northern Rockies and adjacent Plains ; which will result in maximum temperatures expected to be 15 to 25 degrees below average. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php