Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 324 AM EST Wed Dec 06 2017 Valid 12Z Wed Dec 06 2017 - 12Z Fri Dec 08 2017 ...Heavy lake effect snow downwind from the Great Lakes... ...Heavy snow over southwestern Texas... ...Heavy rain possible over the Western/Central Gulf Coast... ...Temperatures will be 15 to 25 degrees below average over parts of the Southern Plains into the Central Gulf Coast... A deep upper-level low over James Bay has multiple spokes of energy rotating around the upper low that will travel across the Great Lakes through Thursday evening. With the addition of cold air flowing over the Lakes, lake effect snow will develop downwind from the Great Lakes with the snow heavy at times also through Thursday evening. In addition, upper-level energy over the Northern High Plains will move southward to the Southern Rockies by Thursday evening. Snow will develop along a secondary front over Northern Plains that will sink southward to the Central/Southern High Plains as the areal coverage decreases by Thursday. Meanwhile, upper-level energy over the California/Mexican and Arizona Border will move southward into Mexico then move eastward over Texas and the Lower Mississippi Valley by Thursday. Additional upper-level energy will move southward into Northern Mexico from the Northern Plains on Thursday into Thursday evening. The energy will aid in the development of snow and rain over parts of the Southern Rockies into Central Texas that will develop into all snow over Western Texas and parts of Southern New Mexico overnight Wednesday with the snow continuing through Thursday evening. Additionally, rain will develop over parts of the Western Gulf Coast into the Central Gulf Coast that will spread eastward into the Southeast with rain continuing over the area through Thursday evening. Elsewhere, a front moving off the Eastern Seaboard will aid in producing rain and snow over parts of Northeast ending by Wednesday afternoon. Rain will also develop along the Southern Mid-Atlantic Coast southward into the Southeast that will continue through Thursday evening. Ziegenfelder Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php