Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 239 PM EST Mon Jan 02 2017 Valid 00Z Tue Jan 03 2017 - 00Z Thu Jan 05 2017 ...Severe thunderstorms and flash flooding possible across portions of the lower Mississippi valley and the Southeast... ...Heavy snow possible through early Tuesday morning across portions of the northern plains and Upper Midwest... ...Heavy snow possible for portions of the Pacific Northwest, northern California, and the Great Basin... A low pressure system will move from the lower Mississippi valley this afternoon to the Ohio valley by Tuesday morning. Widespread showers and thunderstorms are expected through tonight across areas from the lower and mid-Mississippi valley east to the Tennessee and Ohio valleys and the Southeast. Severe thunderstorms as well as flash flooding are possible from the lower Mississippi valley to the Southeast. Please refer to products issued by the Storm Prediction Center for further details on the severe weather threat. On Tuesday, the area of low pressure will weaken over the Ohio valley as energy is transferred to a new area of low pressure along the Mid-Atlantic coast. As this second low develops, precipitation is expected to spread across the Northeast on Tuesday. Sufficient cold air will be in place for precipitation to fall as a mix of snow, sleet, and freezing rain from portions of Upstate New York to northern New England. Snow may be heavy across northern Maine. Another low pressure system will move from the Midwest to the Great Lakes tonight. The system will bring snow, potentially heavy at times, to areas from the northern plains to portions of the Upper Midwest tonight into early Tuesday morning. An area of sleet and freezing rain is possible in the transition zone from snow to rain, across portions of the Upper Midwest. Snow will wind down quickly on Tuesday as the system pulls away into Ontario. Lake effect snows will linger into Wednesday, however. Across the West, onshore flow along with a lingering elongated upper-level trough overhead will keep precipitation in place from central/northern California and southern Oregon east into the central Rockies. Heavy snow is possible for some areas of the Pacific Northwest, northern California, and the Great Basin. On Tuesday precipitation will become even more widespread across the West Coast states as a Pacific low pressure system approaches. Snow levels will rise somewhat as this system moves ashore. Rain and snow are expected to persist across the West through Wednesday. Ryan Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php