Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 235 PM EST Wed Feb 18 2015 Valid 00Z Thu Feb 19 2015 - 00Z Sat Feb 21 2015 ...Temperatures will be 25 to 45 degrees below average from parts of the Upper/Middle Mississippi Valley and the Tennessee Valley eastward to the Mid-Atlantic/Carolinas Coast and the Lower Great Lakes... ...Heavy snow for parts of Northern New England... ...rain/freezing rain and sleet possible for parts of the Lower/Middle Mississippi Valley/Tennessee Valley... Lower pressure over the Mid-Atlantic will move northeastward to Southeastern Canada by Friday. The system will produce light snow from parts of the Great Lakes to the Mid-Atlantic Coast/Northern Appalachians that will move into Northern New England by Thursday morning. The snow over Northern New England will become moderate snow from early Thursday morning through to Thursday night, waning to light snow by Friday morning. In the wake of the low, lake effect snow will develop downwind from the ice free Great Lakes on Thursday. Additionally, cold air associated with a cold area of high pressure over the Northern Plains will move southeastward to the Ohio Valley by Friday morning. Meanwhile, upper-level energy near the Northern Rockies will move southeastward to the Middle Missouri Valley by Friday. The energy will aid in producing light snow over parts of the Northern Plains on Thursday afternoon that will move eastward while expanding into the Upper Mississippi Valley/Upper Great Lakes on Friday morning. Moisture flowing northward out of the Western Gulf of Mexico will move into the Southern Plains and the Lower Mississippi Valley by Friday morning. The moisture will overrun the cold air at the surface producing light snow over parts of the Middle Mississippi Valley and rain over parts of the Western Gulf Coast/Lower Mississippi Valley by Friday morning. In addition, an area of rain/freezing rain and sleet will develop over parts of the Lower Mississippi Valley on Friday morning. Elsewhere, upper-level energy moving onshore over the Northwest on early Thursday morning will move inland to parts of the Northern Rockies by Friday. The energy will produce light rain over parts of the Pacific Northwest starting on Thursday afternoon, beginning to wane by Friday. Snow will develop over parts of the Northern Rockies on Thursday evening that will expand eastward and southward into parts of the Northern High Plains/Central Rockies by Friday morning. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_wbg.php